Building a Safe Room 4PDH /4CE Hours

Home , Foundation (engineering), Safe room

Taking Shelter from the Storm: Building a Safe Room 4PDH /4CE Hours

PDH Academy PO Box 449 Pewaukee, WI 53072

www.pdhacademy.com [email protected] 888-564-9098

Continuing Education for Architects and Engineers Taking Shelter from the Storm: Building a Safe Room Final Exam

1. The severity of a tornado is categorized by the 6. Regarding Safe Room Size, the minimum ______scale: sizing requirement set forth in the ICC-500 for a. BC residential hurricane shelters is ___ square feet b. EF per occupant: c. F a. 10 d. GT b. 15 c. 5 2. Damage from a ______tornado—roofs d. 7 and some walls are torn from structures, some small buildings are destroyed, non-reinforced 7. With regards to Construction Materials, the masonry buildings are destroyed, most trees in materials your builder/contractor will need to forest are uprooted: build your safe room: a. severe a. are generally “special order” b. incredible b. should be available from building material c. moderate suppliers in your community d. considerable c. are usually difficult to obtain d. may not be allowed by local building codes 3. Considering the Basis of Safe Room Design, extensive testing by Texas Tech University and 8. One of the most vulnerable parts of your safe other wind engineering research facilities has room is the: shown that walls, ceilings, and doors commonly a. floor used in building construction to meet minimum b. north wall building code requirements for standard c. window building construction ______withstand the d. door impact of missiles carried by extreme winds: a. can well 9. Many of these shelter products are designed and b. will usually constructed as pre-manufactured units. c. can often a. True d. cannot b. False

4. Considering the Basis of Safe Room Design, most 10. Some SIPs have been designed such that they homes, even new ones constructed according to are capable of resisting the design wind and current building codes, do not provide adequate debris impact criteria of FEMA 320. protection for occupants seeking life-safety a. True protection from tornadoes. b. False a. True b. False

5. Designing a building, or portion of a building, to resist damage from more than one natural hazard requires different, sometimes competing, approaches. a. True b. False

ARCHITECTURE | 5 ThIrd EdITIon

ThIrd EdITIon Introduction

Every year, tornadoes, Introduction hurricanes, and other extreme windstormsINTRODUCTION injure and killEvery people, year, tornadoes, and cause millions of dollarshurricanes, and other extreme worthEvery of year, property tornadoes, damage hurricanes,windstorms in the and injure other and extremekill people, windstorms injure and kill people, and cause millions United States. Even so, andmore cause millions of dollars of dollars worth of propertyworth damage of property in the damage United in the andStates. more Even people so, more build and homesUnited more States. people Even build so, homes more in in tornado-tornado- andand hurricane-prone hurricane-proneand more areas, people possibly build puttinghomes areas,themselves possibly into putting the path themselvesin oftornado- such storms. and hurricane-prone Taking Shelter from the Storm: intoHaving the path a safe of roomsuch builtstorms.areas, for your possibly home putting or small themselves business can help provideinto “near-absolute the path of such protection” storms. Building a Safe Room Havingfor you a safeand yourroom family built for or youremployees from injury or death caused by the dangerousHaving a safe forces room of built extreme for your NOAA homewinds. or smallNear-absolute business protection can help means that, based on NOAA home or small business can help NOAA provideour current “near-absolute knowledge protection” ofprovide tornadoes “near-absolute for andyou hurricanes,and protection” your for you and your AIA CES Course Number: AIAPDH119 familythe occupantsor employees of a safefrom roomfamily injury orbuilt or employees death according caused from to injury this or death caused by guidancethe dangerous will have forces a very byof hightheextreme dangerous probability winds. forces ofNear- being of extreme winds. Near- protected from injury or death. Our knowledge of absolute protection meansabsolute that, basedprotection on means our current that, based on our current Course Description: tornadoes and hurricanesknowledge is based ofon tornadoes substantial and hurricanes, the occupants knowledgemeteorological of tornadoes records asand well hurricanes, as extensive the occupants of a safe room built according to this guidance will have This course material provides safe room designs that will show you how to design and construct investigations of damage to buildings from extreme of a safe room built accordinga very tohigh this probability guidance of beingwill have protected from injury or a safe room for a home or small business. Design options include safe rooms located underneath, winds. It can also relieve some of the anxiety created a very high probability of death.being Our protected knowledge from of tornadoesinjury or and hurricanes is in the basement, in the garage, or in an interior room of a new home or small business. Other by the threat of an oncoming tornado or hurricane. All death. Our knowledge of basedtornadoes on substantial and hurricanes meteorological is records as well as options also provide guidance on how to modify an existing home or small business to add a safe information contained in this publication is applicable based on substantial meteorologicalextensive investigations records as of damagewell as to buildings from room in one of these areas. These safe rooms are designed to provide near-absolute protection to safe rooms for use in homes as well as in small extreme winds. It can also relieve some of the anxiety for families or employees from the extreme winds expected during tornadoes and hurricanes and extensivebusinesses. investigations of damage to buildings from created by the threat of an oncoming tornado or from flying debris, such as wood studs, that tornadoes and hurricanes usually create. extreme winds. It can also relieve some of the anxiety Should you consider buildinghurricane. a safe All informationroom in your contained in this publication createdhome by or thesmall threat business of an isto applicableoncoming provide near-absoluteto tornado safe rooms or for use in homes as well as

Learning Units: hurricane.protection All forinformation you, yourin containedfamily, small businesses. or employeesin this publication during NASA is applicablea tornado or to hurricane?safe rooms The for answer use in dependshomes ason wellyour as 4.0 LU/HSW answers to many questions, including: in small businesses. Should you consider building a safe room in your home or small business to provide near-NASANASA • Do you live in a high-riskabsolute area? protection for you, your family, or employees during a tornado or hurricane? Learning Objective 1: and hurricanes and from flying debris, such as wood The answer depends on your answers to many questions, including: Should• How you quickly consider can you building reach asafe safe shelter room during in your home orstuds, small that business tornadoes to provideand hurricanes near- usually create. Upon completion of this course, the student will understand that “near absolute” protection extreme winds? n Do you live in a high-risk area? means that, based on our current knowledge of tornadoes and hurricanes, the occupants of a safe absolute protection for you, your family, or employees duringIn August a tornado 2008, or the hurricane? International Code Council® room built according to this guidance will have a very high probability of being protected from The• Whatanswer level depends of safety on do your youn answerswantHow quicklyto provide? to manycan you questions, reach safe(ICC including:shelter®), with during the extreme support winds? of the National Storm Shelter Association (NSSA), released a consensus standard injury or death. • What is the cost of a safe nroom? What level of safety do you want to provide? n Do you live in a high-risk area? on the design and construction of storm shelters. n What is the cost of a safe room? Learning Objective 2: Thisn publicationHow quickly will can help you you reach answer safe these shelter and duringother extremeThis standard, winds? the ICC/NSSA Standard for the Design questions so you can decide how best to provide and Construction of Storm Shelters (ICC-500), codifies The student will know how extreme winds can damage a building, will understand the basis of near-absoluten What level protection of safetyTaking for do youshel youT erand fromwant your The to sfamily Tprovide?orm: BUILDING or A SAFEmuch ROOM ofFOR the YOUR extreme-wind HOME OR SMALL B USINESSshelter recommendations v the safe room designs presented in this course, and will know how to best locate a safe room in a employees. It includes the results of research that has of the early editions of FEMA 320 and FEMA 361, n What is the cost of a safe room? home or small business. been underway for more than 30 years, by Texas Tech Design and Construction Guidance for Community Safe University’s Wind Science and Engineering (WISE; Rooms (first edition, July 2000). FEMA 361 contains Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS v Learning Objective 3: formerly known as the Wind Engineering Research detailed guidance for the design and construction Center or WERC) Research Center and other wind of community safe rooms, which also provide near- The student will have access to several sample safe room plans. engineering research facilities, on the effects of extreme absolute protection, the level of protection provided in winds on buildings. the residential safe rooms of this publication. The ICC- 500 provides the minimum design and construction Learning Objective 4: This publication provides safe room designs that requirements for extreme-wind storm shelters will show you and your builder/contractor how to The student will have a better understanding of the approximate costs to add a safe room to an and is expected to be incorporated into the 2009 construct a safe room for your home or small business. existing building as well as to include one in new construction. International Building Code® (IBC®) and International Design options include safe rooms located underneath, Residential Code® (IRC®). It is important that those in the basement, in the garage, or in an interior room involved in the design, construction, and maintenance of a new home or small business. Other options also of storm shelters be knowledgeable of both FEMA provide guidance on how to modify an existing home guidance and ICC standards that pertain to sheltering or small business to add a safe room in one of these from extreme winds. areas. These safe rooms are designed to provide near- An extensive list of individuals who have made significant contributions to this publication absolute protection for you, your family, or employees The safe room designs presented in this publication is available in the online version of this class. from the extreme winds expected during tornadoes meet or exceed all tornado and hurricane design

58 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 59 ThIrd EdITIon

ThIrd EdITIon Introduction

58 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 59 INTRODUCTION ThIrd EdITIon

This publication will help you answer these and other questions so you can decide how best to TYPICAL TORNADO DAMAGE provide near-absolute protection for you and your family or employees. It includes the results of research that has been underway for more than 30 years, by Texas Tech University’s Wind Science and Engineering (WISE; formerly known as the Wind Engineering Research Center or WERC) Research Center and other wind engineering research facilities, on the effects of extreme winds on buildings.

This publication provides safe room designs that will show you and your builder/contractor how criteria of theto construct ICC-500 for a safeboth roomthe tornado for your and home or smallimpact business. of typical Design flying options debris. includeWhen installation safe rooms seCTion i: UNDERSTANDING THE HAZARDS ThIrd EdITIon hurricane hazards.located underneath, in the basement, in the andgarage, foundation or in an requirements interior room are of addressed a new home by a localor design professional, these designs will meet or exceed The Nationalsmall Association business. of OtherHome optionsBuilders also(NAHB) provide guidance on how to modify an existing home or small the design requirements set forth in the ICC-500 for Research Center has evaluated these designs for business to add a safe room in one of these residentialareas. These and safesmall rooms community are designed shelters (less to provide than 16 construction methods, materials, and costs for the near-absolute protection for you, your family,persons) or employees for both from tornado the extreme or hurricane winds hazards. expected The iIncredible:ncredible: Strong frame houses are lifted earlier editions of this publication. Engineers at during tornadoes and hurricanes and from flyingsafe rooms debris, in thissuch publication as wood studs,have been that designedtornadoes with and from foundations, reinforced concrete Texas Tech University, engineering consultants, Strong frame houses are lifted from foundations, life safety as the primary consideration. structures are damaged, automobile- and FEMA hurricaneshave confirmed usually the create.design requirements EF5ef5 reinforced concrete structures are damaged, for the expected forces from wind pressure and the sizedautomobile-sized missiles become missiles airborne, become airborne, trees are trees are completely debarked.debarked. TORNADOTORNADO OCCURRENCE OCCURRENCE AND ANDRESULTANT RESULTANT LOSSES LOSSES ARE ARE INCREASING INCREASING In 1950, the InNational 1950, Weather the National Service (NWS)Weather started keepingService organized (NWS) records started of tornadoes keeping Devastating: Well-constructed houses are organized records of tornadoes occurring in the United States (U.S.). Since that destroyed,Well-constructed some houses structures are destroyed, are lifted somefrom structures time, 1953 wasoccurring the deadliest in the year United (519 deaths). States ef4 foundationsare lifted from and foundations blown some and distance,blown some distance, The average (U.S.).in recent Since years thathas beentime, 62 1953 deaths was per EF4 cars areare blown blown some some distance, distance, large large debris debris becomes year. Deaths thecaused deadliest by tornadoes year were(519 38, deaths). 67, and airborne. 81 for 2005,The 2006, average and 2007, in respectively.recent years As hasof becomes airborne. May of this year,been 110 62 deathsdeaths have per been year. caused Deaths by tornadoes. caused by tornadoes were 38, 67, and 81 for 2005, 2006, and 2007, In addition to deaths, tornadoes cause injuries and sSevere:evere: Roofs and some walls are torn respectively. As of May of this year, devastating losses of personal property. Insurance from structures, some small buildings are 110 deaths have been caused by Roofs and some walls are torn from structures, some claim losses from a single tornadic event of $1 ef3 destroyed, non-reinforced masonry buildings billion and highertornadoes. are becoming more frequent. EF3 small buildings are destroyed, non-reinforced masonry arebuildings destroyed, are destroyed, most trees most in trees forest in areforest are So far in 2008,In tornadoesaddition tohave deaths, resulted tornadoes in insured uprooted. losses of morecause than $1injuries billion and(almost devastating $850 million This photograph from FEMA’s photo library shows of which from the mid-South outbreaks on February losses of personal property. Thisthe photographvivid reality from of FEMA’show lives photo are library impacted shows bythe vivid 5 and 6; in March, Atlanta and its surrounding realitytornadoes. of how lives are impacted by tornadoes. counties wereInsurance struck by a claimtornado losses that caused from $349 a single tornadic event of $1 billion (Lafayette,(Lafayette, TN TN – February – February 5, 2000) 5, 2000) million in losses). SOURCE: Jocelyn Augustino /FEMA and higher are becoming more SOURCE: JOCEly N AUgUSTINO/FEMA Considerable: Roof structures are damaged, Although hurricanesfrequent. and So earthquakesfar in 2008, generally tornadoes mobile homes are destroyed, debris generate higher losses per event, since 1953, tornadoes (and related weather events) have caused an average of ef2 Roof structures are damaged, mobile homes are have resulted in insured losses of more than $1 billion (almost $850 million of which from the EF2 becomes airborne (missiles are generated), 57 percent of all U.S. insured catastrophic losses. In 2007, that number increased to 69 percent. destroyed, debris becomes airborne (missiles are mid-South outbreaks on February 5 and 6; in March, Atlanta and its surrounding counties largegenerated), trees largeare snapped trees are snappedor uprooted. or uprooted. Source: A.M.were Best, struckCNN by a tornado that caused $349 million in losses). Although hurricanes and earthquakes generally generate higher losses per event, since 1953, SECTION tornadoesI | UNDERSTANDING (and related weather THE events) cloudhave orcaused underneath an average a cumuliform of 57 percentcloud, and of oftenall U.S. insured catastrophic losses. In 2007, that (butnumber not always)increased visible to 69 as apercent. funnel cloud.” Tornadoes moderate: Roof surfaces are peeled off, HAZARDS typically occur in the spring and summer months, Moderate: SoUrce: A.M. BeST, cNN windows are broken, some tree trunks Almost every state in the United States has been but can occur at any time in any part of the country. ef1 areRoof snapped, surfaces are unanchored peeled off, windowsmobile homes are broken, some affected by extreme windstorms such as tornadoes Tornadoes are sometimes spawned by hurricanes. The EF1 tree trunks are snapped, unanchored mobile homes are and hurricanes. Virtually every state has been affected severity of a tornado is categorized by the Enhanced areoverturned, overturned, attached attached garages garages may be maydestroyed. be by a “considerable”vi tornado (see the termsTaking inshel FigureTer from TheFujita sTorm: Scale BUILDING (EF Scale).A SAFE ROOMAs of FOR February YOUR HOME 2007, OR theSMALL EF BScaleUSINESS destroyed. I-1). All Atlantic and Gulf of Mexico coastal areas in (see Figure I-1) was adopted by the National Oceanic the United States – including coastal areas of Puerto and Atmospheric Administration (NOAA) to replace Rico and the U.S. Virgin Islands – and coastal areas of Hawaii have been affected by hurricanes. Even in states definition not normally considered to be susceptible to extreme Chimneys are damaged, tree In this publication, the term missiles refers to lLight:ight: windstorms, there are areas that experience dangerous debris and other objects picked up by the wind ef0 branches are broken, shallow-rooted trees extreme winds. These areas are typically near mountain EF0 Chimneys are damaged, tree branches are broken, and moved with enough force to damage and even are toppled. ranges, and include the Pacific Northwest coast. shallow-rooted trees are toppled. penetrate windows, doors, walls, and other parts of a building. In general, the stronger the wind, the What Is a Tornado? larger and heavier the missiles it can carry and the greater the risk of severe damage or injury. But even Figure I-1. TypicalFigure tornado I-1. Typical damage tornado damage According to the American Meteorological Society’s small stones, branches, and other lighter missiles Glossary of Meteorology, a tornado is “a violently can easily break glass doors and windows. rotating column of air, pendant from a cumuliform 2 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS

60 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 61 INTRODUCTION ThIrd EdITIon

60 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 61 TYPICAL HURRICANE DAMAGE

seCTion i: UNDERSTANDING THE HAZARDS ThIrd EdITIon

seCTion i: UNDERSTANDING THE HAZARDS ThIrd EdITIon Whatthe Fujita i sScale a h(F urricane?Scale). The EF Scale is designed as are U.S. island possessions and territories. Hurricanes similar to the F Scale, but has been revised to have a between 1900 and 2006 resulted in 17,832 deaths. Hurricanesgreater number are of categorized Damage Indicators, by the which Saffir-Simpson are used scale (see Figure I-3). In recent years, the U.S. territories of Puerto Rico, to characterize the degree of damage experienced by American Samoa, and Guam have been seriously buildings during a tornado. In the United States, 279 hurricanes were recordedaffected to have by madenumerous landfall tropical between cyclones. 1851 and 2006.Not all Over parts ofone-third each state of are these at equal hurricanes risk from (96) were classified as major hurricanes (designated tornadoes. For example, while Texas has the highest Categorynumber of 3recorded and higher tornadoes, on the the Saffir-Simpson state’s least HurricaneDo You Scale). Need Hurricanesa Safe Room? have made landfall intornado-prone Florida more area than (along in anythe Gulf other coast) state. has The been second On most the basishurricane-affected of 60 years of tornado state history is Texas, and butmore everyhit by fewerstate tornadoeson the g thanulf coast northeastern and bordering Arkansas. the Atlanticthan 150 Ocean years ofis hurricanesusceptible history, to damage the United caused States Comparing the numbers of tornadoes recorded in by hurricanes, as are U.S. island possessions and hasterritories. been divided Hurricanes into four betweenzones that 1900geographically and 2006 different areas within a state can give you a better reflect the number and strength of extreme resultedunderstanding in 17,832 of potential deaths. tornado activity in those windstorms. Figure I-4 shows these four zones. Zone areas. Figure I-2 shows the summary of recorded EF3, IV has experienced the most and the strongest tornado EF4, and EF5 tornadoes per 2,470 square miles in In recent years, the U.S. territories of Puerto Rico, activity.American Zone Samoa, III has experienced and guam significant have been tornado the United States and its possessions and territories. activity and includes coastal areas that are susceptible seriouslyBetween 1950 affected and 2006, by numerous tornadoes caused tropical 5,506 cyclones. to hurricanes. The release of the ICC-500 has codified deaths and 93,287 injuries. much of FEMA’s guidance for safe room design and construction. However, there are additional details in What Is a Hurricane? the ICC-500 regarding hurricane shelters, including a new shelter design wind speed map that could be Hurricanes are categorized by the Saffir-Simpson scale helpful to understanding your risk of extreme-wind (see Figure I-3). events due to hurricanes. A safe room designed and constructed to the prescriptive designs included in In the United States, 279 hurricanes were recorded to this publication (and properly sited to address flood have made landfall between 1851 and 2006. Over one- hazards) will meet or exceed the ICC-500 residential third of these hurricanes (96) were classified as major and small community shelter (less than 16 people) hurricanes (designated Category 3 and higher on the design criteria. Saffir-Simpson Hurricane Scale). Hurricanes have made landfall in Florida more than in any other state. The A safe room using the prescriptive designs of this second most hurricane-affected state is Texas, but every publication should not be installed in a hurricane- state on the Gulf coast and bordering the Atlantic prone area that may be inundated by storm surge Ocean is susceptible to damage caused by hurricanes, from any hurricane, including Category 5 hurricanes.

Figure I-2. The number of tornadoes recorded per 2,470 square miles Figure I-2. The number of tornadoes recorded per 2,470 square miles

Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 3

seCTion i: UNDERSTANDING THE HAZARDS ThIrd EdITIon seCTion i: UNDERSTANDING THE HAZARDS ThIrd EdITIon Whatthe Fujita i sScale a h(F urricane?Scale). The EF Scale is designed as are U.S. island possessions and territories. Hurricanes similar to the F Scale, but has been revised to have a between 1900 and 2006 resulted in 17,832 deaths. Hurricanesgreater number are of categorized Damage Indicators, by the which Saffir-Simpson are used scale (see Figure I-3). In recent years, the U.S. territories of Puerto Rico, to characterize the degree of damage experienced by American Samoa, and Guam have been seriously buildings during a tornado. In the United States, 279 hurricanes were recordedaffected to have by madenumerous landfall tropical between cyclones. 1851 and 2006.Not all Over parts ofone-third each state of are these at equal hurricanes risk from (96) were classified as major hurricanes (designated tornadoes. For example, while Texas has the highest Categorynumber of 3recorded and higher tornadoes, on the the Saffir-Simpson state’s least HurricaneDo You Scale). Need Hurricanesa Safe Room? have made landfall intornado-prone Florida more area than (along in anythe Gulf other coast) state. has The been second On most the basishurricane-affected of 60 years of tornado state history is Texas, and butmore everyhit by fewerstate tornadoeson the g thanulf coast northeastern and bordering Arkansas. the Atlanticthan 150 Ocean years ofis hurricanesusceptible history, to damage the United caused States Comparing the numbers of tornadoes recorded in by hurricanes, as are U.S. island possessions and hasterritories. been divided Hurricanes into four betweenzones that 1900geographically and 2006 different areas within a state can give you a better reflect the number and strength of extreme resultedunderstanding in 17,832 of potential deaths. tornado activity in those windstorms. Figure I-4 shows these four zones. Zone areas. Figure I-2 shows the summary of recorded EF3, IV has experienced the most and the strongest tornado EF4, and EF5 tornadoes per 2,470 square miles in In recent years, the U.S. territories of Puerto Rico, activity.American Zone Samoa, III has experienced and guam significant have been tornado the United States and its possessions and territories. activity and includes coastal areas that are susceptible seriouslyBetween 1950 affected and 2006, by numerous tornadoes caused tropical 5,506 cyclones. to hurricanes. The release of the ICC-500 has codified deaths and 93,287 injuries. much of FEMA’s guidance for safe room design and construction. However, there are additional details in What Is a Hurricane? the ICC-500 regarding hurricane shelters, including a new shelter design wind speed map that could be Hurricanes are categorized by the Saffir-Simpson scale helpful to understanding your risk of extreme-wind (see Figure I-3). events due to hurricanes. A safe room designed and constructed to the prescriptive designs included in In the United States, 279 hurricanes were recorded to this publication (and properly sited to address flood have made landfall between 1851 and 2006. Over one- hazards) will meet or exceed the ICC-500 residential third of these hurricanes (96) were classified as major and small community shelter (less than 16 people) hurricanes (designated Category 3 and higher on the design criteria. Saffir-Simpson Hurricane Scale). Hurricanes have made landfall in Florida more than in any other state. The A safe room using the prescriptive designs of this second most hurricane-affected state is Texas, but every publication should not be installed in a hurricane- state on the Gulf coast and bordering the Atlantic prone area that may be inundated by storm surge Ocean is susceptible to damage caused by hurricanes, from any hurricane, including Category 5 hurricanes.

Figure I-2. The number of tornadoes recorded per 2,470 square miles Figure I-2. The number of tornadoes recorded per 2,470 square miles

Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 3

62 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE 4ARCHITECTURE Taking shelTer from The sTorm:Taking BUILDING Shelter A fromSAFE theROOM Storm: FOR YOUR Building HOME a ORSafe SMALL Room B USINESS | 63 seCTion i: UNDERSTANDING THE HAZARDS ThIrd EdITIon Further, it is best not to install residential or small areas, design wind events in the code range from 90 to community safe rooms in any area susceptible to 150 mph. A tornado or extreme hurricane can cause flooding defined by the 500-year floodplain. However, winds much greater than those on which local code in areas not prone to storm surge, a safe room may be requirements are based. Having a home built to “code” installed within mapped floodplains only when the does not mean that your home can withstand wind Catastrophic: designs provided herein: from any event, no matter how extreme. The safe room Catastrophic: Roof damage is designs in this publication provide a place to seek safe • Are acceptedseCT asion meeting i: UNDERSTANDING the safe room elevation THE HAZARDS flood ThIrd EdITIon Roofconsiderable damage is and considerable widespread, and window widespread, and shelter during these extreme-wind events. criteria presented in the text box on pages 76 and 77 C5 windowdoor damage and door is severe, damage there is severe, are extensive there are C5 The worksheet on page 68 will help you determine extensiveglass failures, glass failures,some complete some complete buildings buildings fail. • Comply with all local floodplain ordinances your level of risk from these extreme events and will fail. • Are coordinated with local emergency management assist you in your consideration of a safe room. If you In this publication, the termdecide storm that surge you need means a safe room,an abnormal Section II willrise help in Your home or place of business is probably built in you and your builder/contractor in planning your safe accordance with local buildingsea codeslevel thataccompanying consider the a hurricane or other intense storm, and whose room. To learn more about the wind history for the effects of minimum, “code-approved”height is the design difference winds for between the observed level of the sea surface and area where you live, check with your local building your area. Building codes require that buildings be able DefiniTion the level that would have occurredofficial, inmeteorologist, the absence emergency of the cyclone.management Storm to withstand a wind event. In most tornado- Extreme: “design” surge (see Figure I-5) is usuallyofficial, estimated or television by subtractingweather reporter. the normal or extreme: Extensive damage is done to prone regions, the building code design wind event is C4 Extensiveroofs, windows, damage and is done doors; to roof roofs, systems windows, on and a wind event with 90 mph astronomicwinds. For hurricane-prone high tide from the observed storm tide. C4 doors;small roofbuildings systems completely on small fail; buildings some curtain completely fail;walls some fail. curtain walls fail.

Extensive: extensive: large trees are toppled, some C3C3 Largestructural trees damageare toppled, is done some to structuralroofs, mobile damage 15-foot Surge 17-foot Storm Tide ishomes done to are roofs, destroyed, mobile structural homes are damage destroyed, is structuraldone to small damage homes is done and toutility small buildings. homes and 2-foot Normal High Tide utility buildings. Mean Sea Level

Figure I-5. Storm surge Figure I-5. Storm surge

A safe room may be designed and constructed Moderate:moderate: Some trees are toppled, some to meet all applicable FEMA criteria. However, C2C2 roof coverings are damaged, major damage use of the safe room during a hurricane may not Someis done trees to aremobile toppled, homes. some roof coverings are be in compliance with mandatoryA safe room evacuation designed to protect you and your family or employees from damaged, major damage is done to mobile homes. warning orders of the local jurisdiction.a hurricane FEMA recommends or tornado shouldA safe not room be builtdesigned in an to protectarea expected you and your to be that allW safearning room occupantsflooded comply during with local a hurricane, thunderstorm,family or employees or otherfrom asevere hurricane weather or tornado event. jurisdictional directions andResidents orders during of hazard-prone a coastalshould areasnot be shouldbuilt in anabide area byexpected the warnings to be of hurricane event (which may include evacuation) their local emergency services personnel and evacuateflooded toduring safer a ground.hurricane, The thunderstorm, protection or from other even if they have constructed a safe room. severe weather event. Residents of hazard-prone wind provided by safe rooms and shelters is quicklycoastal negated areas should when abide people by the find warnings themselves of their trapped and inundated by floodwaters. Minimal: local emergency services personnel and evacuate to minimal: Damage is done primarily to safer ground. The protection from wind provided C1 Damageshrubbery is done and trees,primarily unanchored to shrubbery mobile and trees, definitionIf you do not know whether your home or small businessby safe rooms is inand a sheltersstorm issurge quickly area negated or other when C1 In this publication, the term storm surge means unanchoredhomes are damaged,mobile homes some are signs damaged, are some area subject to flooding, check the community peopleservice find section themselves of your trapped local andphone inundated book forby an abnormal rise in sea level accompanying a signsdamaged, are damaged, no real damageno real damage is done isto done to storm surge evacuation information or ask your localfloodwaters. emergency management or floodplain structures.structures. hurricane or other intense storm, and whose height is managementthe difference between official. the observed level of the If you do not know whether your home or small sea surface and the level that would have occurred business is in a storm surge area or other area in the absence of the cyclone. Storm surge (see subject to flooding, check the community service Figure I-3. TypicalFigure hurricane I-3. Typical damage hurricane damage Figure I-5) is usually estimated by subtracting the section of your local phone book for storm surge normal or astronomic high tide from the observed evacuation information or ask your local emergency storm tide. management or floodplain management official. Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 5 homeowner’s Worksheet: assessing Your risk To complete the worksheet on page 10, refer to the tornado occurrence and wind hazard maps for 64 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE tornadoesARCHITECTURE and hurricanes on pages 3 and 7 (FiguresTaking I-2Shelter and from I-4, therespectively). Storm: Building Using a Safe the Room map | on65 page 3, note how many tornadoes were recorded per 2,470 square miles for the area where you live. Find the row on the worksheet that matches that number. Next, look at the map on page 7 and note the wind zone (I, II, III, or IV) in which you live. Find the matching column on the worksheet. Finally, find the box inside the worksheet that lines up with both the number of tornadoes per

8 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS seCTion i: UNDERSTANDING THE HAZARDS ThIrd EdITIon Further, it is best not to install residential or small areas, design wind events in the code range from 90 to community safe rooms in any area susceptible to 150 mph. A tornado or extreme hurricane can cause flooding defined by the 500-year floodplain. However, winds much greater than those on which local code in areas not prone to storm surge, a safe room may be requirements are based. Having a home built to “code” installed within mapped floodplains only when the does not mean that your home can withstand wind Catastrophic: designs provided herein: from any event, no matter how extreme. The safe room Catastrophic: Roof damage is designs in this publication provide a place to seek safe • Are acceptedseCT asion meeting i: UNDERSTANDING the safe room elevation THE HAZARDS flood ThIrd EdITIon Roofconsiderable damage is and considerable widespread, and window widespread, and shelter during these extreme-wind events. criteria presented in the text box on pages 76 and 77 C5 windowdoor damage and door is severe, damage there is severe, are extensive there are C5 The worksheet on page 68 will help you determine extensiveglass failures, glass failures,some complete some complete buildings buildings fail. • Comply with all local floodplain ordinances your level of risk from these extreme events and will fail. • Are coordinated with local emergency management assist you in your consideration of a safe room. If you In this publication, the termdecide storm that surge you need means a safe room,an abnormal Section II willrise help in Your home or place of business is probably built in you and your builder/contractor in planning your safe accordance with local buildingsea codeslevel thataccompanying consider the a hurricane or other intense storm, and whose room. To learn more about the wind history for the effects of minimum, “code-approved”height is the design difference winds for between the observed level of the sea surface and area where you live, check with your local building your area. Building codes require that buildings be able DefiniTion the level that would have occurredofficial, inmeteorologist, the absence emergency of the cyclone.management Storm to withstand a wind event. In most tornado- Extreme: “design” surge (see Figure I-5) is usuallyofficial, estimated or television by subtractingweather reporter. the normal or extreme: Extensive damage is done to prone regions, the building code design wind event is C4 Extensiveroofs, windows, damage and is done doors; to roof roofs, systems windows, on and a wind event with 90 mph astronomicwinds. For hurricane-prone high tide from the observed storm tide. C4 doors;small roofbuildings systems completely on small fail; buildings some curtain completely fail;walls some fail. curtain walls fail.

Figure I-5. Storm surge Figure I-5. Storm surge

8 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS ThIrd EdITIon seCTion i: UNDERSTANDING THE HAZARDS Homeowner’s Worksheet: Assessing Your Risk Hurricane-susceptible regions can be seen in Figure I-4, running from the southern tip of Texas to the To complete the worksheet on page 68, refer to Northeast. Revised hurricane shelter design wind the tornado occurrence and wind hazard maps for seCTion i: UNDERSTANDING THE HAZARDS speeds have been releasedThIrd inEd theITIon ICC-500. For the tornadoes and hurricanes on pages 62 and 66 (Figures purpose of the prescriptive solutions offered in this I-2 and I-4, respectively). Using the map on page 62, publication, the wind speeds given in Figure I-4 are 2,470 squarenote miles how in manyyour areatornadoes and your were wind recorded zone. per The 2,470 color of thatused box to calculatetells you pressures the level and of required resistances for square miles for the area where you live. Find the row residential safe rooms. ThIrd EdITIon your risk fromon extreme the worksheet windsseCT thatandion matcheshelps i: UNDERSTANDING you that decide number. whether THENext, HAZARDS to build a safe room. look at the map on page 66 and note the wind zone For example, if you live in Hattiesburg, MS, you would see that Hattiesburg is in an area shaded medium Hurricane-susceptible(I, II,2,470 III, or regions squareIV) in which milescan beyou in seen your live. inareaFind Figure theand matching I-4,your running wind zone. from The the southerncolor of that tip ofbox Texas tells toyou the level of the Northeast.column Revised on thehurricane worksheet. shelter Finally, design find wind the speedsbox inside have orange been releasedon the map in onthe page ICC-500. 62. So according to the the worksheetyour risk fromthat linesextreme up with winds both and the helps number you of decide map whether key, the to numberbuild a ofsafe tornadoes room. per 2,470 square

Harrisburg For the purpose of the prescriptive solutions offered in this publication, the wind speeds given in tornadoes per 2,470 square miles in your area and your miles in the Hattiesburg area is 11-15. Figure I-4 arewind used zone. to calculate The color pressures of that box and tells required you the levelresistances of for residential safe rooms. Hurricane-susceptible regions can be seen in FigureOn I-4,the maprunning on page from 66, the Hattiesburg southern tipappears of Texas within to your risk from extreme winds and helps you decide the Northeast. Revised hurricane shelter design windthe red-shadedspeeds have area. been The releasedmap key tells in the you ICC-500. that whether to build a safe room. For the purpose of the prescriptive Forsolutions example, offered ifHattiesburg you in livethis inpublication, isHattiesburg, in Wind theZone MS, wind IV. speeds given in you would see that Hattiesburg is in an area Figure I-4 are used to calculate pressures and requiredThe box resistances where the for11-15 residential row and thesafe Zone rooms. IV column shaded mediummeet orange is shaded on the dark map blue, on which page shows that you live 3. So accordingin toFor an the areaexample, map of high key, if risk.theyou numberAlive safe in roomHattiesburg, is the preferred MS, method of wind protection in high-risk areas. Note of tornadoes per you2,470 would square see miles that Hattiesburg in the is in an area Hattiesburg areathat is some11-15. areas of low or moderate risk, shown as pale blueshaded or medium medium blue orange in the worksheet,on the map are on within page the region3. So of according the United to States the map that key,is subject the number to hurricanes (seeof Figuretornadoes I-4). Ifper you 2,470 live in square this hurricane-susceptible miles in the region,Hattiesburg your risk area is considered is 11-15. high, even though the worksheet indicates only a moderate or low risk.

On the map on page 7, Hattiesburg Hattiesburg appears within the red-shaded area. The map key tells you that Hattiesburg is in Wind Zone IV. On the map on page 7, Hattiesburg Hattiesburg appears within the red-shaded area. The box where theThe 11-15 map row key and tells the you Zone that Hattiesburg is in IV column meet isWind shaded Zone dark IV. blue, which shows that you live in an area of high risk. A safe room is the preferred method of wind protection in high-risk areas.The Note box that where some the areas 11-15 of row low and or moderate the Zone risk, shown as pale blue or medium blue in the worksheet, IV column meet is shaded dark blue, whichW IND ZoNE (SEE FIGURE I-4) are within the region of shows that you live in an area of highI risk. A safeII room is theIII preferred methodIV of wind protection the United States that is in high-risk areas. Note that someLoW RareasISK of lowLoW orRISK moderateLoW risk, RISK shownMoDERATE as pale RISK blue or medium

< 1 subject to hurricanesblue in(see the worksheet, H H ES WIND ZoNE (SEE FIGURE I-4)

Figure I-4). If you live in ILES are within the region of1 – 4 LoW RISK MoDERATE RISK HIGH RISK HIGH RISK I II III IV this hurricane-susceptiblethe United States that is H

RNAD o LoW RISK LoW RISK LoW RISK MoDERATE RISK

< 1 region, your risk is

subject to hurricanes M UARE 5(see – 10 LoW RISK MoDERATE RISK HIGH RISK HIGH RISK

To H H ES IGURE I-2) considered high, even F H

Figure I-4). If you live in ILES though the worksheet 1 – 4 LoW RISK MoDERATE RISK HIGH RISK HIGH RISK this hurricane-susceptible11 – 15 HIGH RISK HIGH RISK HIGH RISKH HIGH RISK Figure I-4. Wind zones in the UnitedFigure States I-4. Wind zones in the United States (S EE F indicates only a moderateregion, your risk is RNAD o

M UARE 5 – 10 LoW RISK MoDERATE RISK HIGH RISK HIGH RISK UMBER o or low risk. H To IGH RISK HIGH RISK HIGH RISK HIGH RISK IGURE I-2)

N > 15 PER 2,470 Sq considered high, even F Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 7 H though the worksheet 11 – 15 HIGH RISK HIGH RISK HIGH RISK HIGH RISK indicates only a moderate (S EE F 66 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 67 Taking shelTer from orThe low sTorm: risk. BUILDING A SAFE ROOM FOR UMBER o YOUR HOME OR SMALLHIGH BUSINESS RISK HIGH RISK HIGH RISK9 HIGH RISK N > 15 PER 2,470 Sq

Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 9 ThIrd EdITIon seCTion i: UNDERSTANDING THE HAZARDS Homeowner’s Worksheet: Assessing Your Risk Hurricane-susceptible regions can be seen in Figure I-4, running from the southern tip of Texas to the To complete the worksheet on page 68, refer to Northeast. Revised hurricane shelter design wind the tornado occurrence and wind hazard maps for seCTion i: UNDERSTANDING THE HAZARDS speeds have been releasedThIrd inEd theITIon ICC-500. For the tornadoes and hurricanes on pages 62 and 66 (Figures purpose of the prescriptive solutions offered in this I-2 and I-4, respectively). Using the map on page 62, publication, the wind speeds given in Figure I-4 are 2,470 squarenote miles how in manyyour areatornadoes and your were wind recorded zone. per The 2,470 color of thatused box to calculatetells you pressures the level and of required resistances for square miles for the area where you live. Find the row residential safe rooms. ThIrd EdITIon your risk fromon extreme the worksheet windsseCT thatandion matcheshelps i: UNDERSTANDING you that decide number. whether THENext, HAZARDS to build a safe room. look at the map on page 66 and note the wind zone For example, if you live in Hattiesburg, MS, you would see that Hattiesburg is in an area shaded medium Hurricane-susceptible(I, II,2,470 III, or regions squareIV) in which milescan beyou in seen your live. inareaFind Figure theand matching I-4,your running wind zone. from The the southerncolor of that tip ofbox Texas tells toyou the level of the Northeast.column Revised on thehurricane worksheet. shelter Finally, design find wind the speedsbox inside have orange been releasedon the map in onthe page ICC-500. 62. So according to the the worksheetyour risk fromthat linesextreme up with winds both and the helps number you of decide map whether key, the to numberbuild a ofsafe tornadoes room. per 2,470 square

< 1 subject to hurricanesblue in(see the worksheet, H H ES WIND ZoNE (SEE FIGURE I-4)

Figure I-4). If you live in ILES are within the region of1 – 4 LoW RISK MoDERATE RISK HIGH RISK HIGH RISK I II III IV this hurricane-susceptiblethe United States that is H

RNAD o LoW RISK LoW RISK LoW RISK MoDERATE RISK

< 1 region, your risk is

subject to hurricanes M UARE 5(see – 10 LoW RISK MoDERATE RISK HIGH RISK HIGH RISK

To H H ES IGURE I-2) considered high, even F H

M UARE 5 – 10 LoW RISK MoDERATE RISK HIGH RISK HIGH RISK UMBER o or low risk. H To IGH RISK HIGH RISK HIGH RISK HIGH RISK IGURE I-2)

Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 9 seCTion i: UNDERSTANDING THE HAZARDS ThIrd EdITIon

Table I-1. Homeowner’s Worksheet • Extra change of clothing per person (store in plastic You can get more information about emergency Table I-1. Homeowner’s Worksheet ThIrd EdITIon trash bagsse toCT keepion clean i UNDERSTANDING and dry) THE HAZARDS planning from American Red Cross (ARC) and FEMA publications, which you can obtain free of charge WIND ZoNE (SEE FIGURE I-4) • Appropriate outer wear (e.g., sunglasses, ponchos, by calling FEMA at 1-800-480-2520, or by writing to yjackets,ou can gloves, get more headwear, information boots, aboutetc.) emergency planning from American Red Cross (ARC) and I II III IV FEMA, P.O. Box 2012, Jessup, MD 20794-2012. These • FEMA Bedding publications, materials such which as pillows you can and obtain blankets free or of chargepublications by calling include FEMA the at following:1-800-480-2520, LoW RISK LoW RISK LoW RISK MoDERATE RISK orsleeping by writing bags to FEMA, P.O. Box 2012, Jessup, MD 20794-2012. These publications include the < 1 Planning Documents: H H following:

ES • Special items for: Are You Ready? An In-depth Guide to Citizen Preparedness, ILES • babies – formula, diapers, bottles, powdered milk 1 – 4 LoW RISK MoDERATE RISK HIGH RISK HIGH RISK FEMA IS-22 Planning• children Documents:– entertainment items such as books, H Emergency Preparedness Checklist, FEMA L-154 (ARC Aregames, You Ready? or toys An In-depth Guide to Citizen Preparedness, FEMA IS-22

RNAD o 4471) Emergency• adults – contact Preparedness lenses and Checklist supplies,, extraFEMA glasses, l-154 (ARC 4471) M UARE 5 – 10 LoW RISK MoDERATE RISK HIGH RISK HIGH RISK To and a sufficient supply of prescription medications Emergency Food and Water Supplies, ARC 5055 IGURE I-2) F H Emergency Food and Water Supplies, ARC 5055 • pets – appropriate supplies such as water (1/2 gallon Your Family Disaster Supplies Kit, ARC 4463 Yourper Familyday), food, Disaster leash, Supplies ID tag, carrying Kit, ARC container, 4463 etc. 11 – 15 HIGH RISK HIGH RISK HIGH RISK HIGH RISK Preparing for Disasters for People with Special Needs, FEMA

(S EE F Preparing for Disasters for People with Special Needs, FEMA 476 (ARC 4497) • Additional items: 476 (ARC 4497) • important documents such as insurance documents, Safe Room Documents: UMBER o HIGH RISK HIGH RISK HIGH RISK HIGH RISK safea list r oomof all Documents:your important contacts (e.g., family,

N > 15 PER 2,470 Sq Designdoctors, and insurance Construction agents), Guidance banking information,for Community SafeDesign Rooms and ,Construction FEMA 361 Guidance for Community Safe Rooms, FEMA 361 Safeleases/ Room mortgage, and Community proof of occupancy Shelter Resource (such as a CD , FEMA 388 CD utility bill), and a waterproof container in which to Safe Room and Community Shelter Resource CD, FEMA LoW RISK Need for an extreme-wind safe room is a matter of homeowner or small business Tornadokeep these Protection documents - Selecting Refuge Areas in Buildings, FEMA 431 owner preference. 388 CD These• ABC2 publicationsrated fire extinguisher are also available on the FEMA web site – Tornado Protection - Selecting Refuge Areas in Buildings, MoDERATE RISK Safe room should be considered for protection from extreme winds. http://www.fema.go• roofing tarps or plasticv – and sheeting at the American Red CrossFEMA web 431 site – http://www.redcross.org. • roll of large heavy-duty trash bags and duct tape HIGH RISK Safe room is the preferred method of protection from extreme winds. These publications are also available on the FEMA web • money (cash) site – http://www.fema.gov – and at the American Red Safe room is the preferred method of protection from extreme winds if the home or Cross web site – http://www.redcross.org. H small business is in a hurricane-susceptible region.

Emergency Planning and Emergency Supply Kit • A first-aid kit, including necessary prescription medicines, bandages, and antibiotic ointment Whether or not you decide that you need a safe room in youremergency home or small Planning business, you and can take emergency two • s Toolsupply and supplies:kit importantWhether steps or tonot provide you decide near-absolute that you protection need a safe room• flashlightin your home (one orper small person; business, do not bringyou cancandles or The Department of Homeland Security (DHS), has developed for you,take your two family,important or employees steps to provide during anear-absolute hurricane protectionanything for that you, lights your with family, a flame) or employees The Department of Homeland Security (DHS), has developed the READY.gov web or tornado: prepare an emergency plan and put an the READy.gov web site. you can find emergency planning • battery-operated radio or television and NOAA1 site. You can find emergency planning and preparation guidance for all types of emergencyduring supplya hurricane kit together. or tornado: If you prepare decide to an build emergency plan and put an emergency supply kit and preparation guidance for all types of potential hazards. weather radio potential hazards. To obtain a copy of Preparing Makes Sense. Get Ready Now, go to a safetogether. room, your If you emergency decide to plan build should a safe include room, your emergency plan should include notifying local http://www.ready.govTo obtain a copy of. Preparing Makes Sense. Get Ready Now, go to notifyingemergency local emergency managers, managers, first responders first responders (local fire stations),• cellular phoneand family or Citizen’s members Band or (CB) others radio outside http://www.ready.gov. (localthe fire immediate stations), areaand family that you members have aor safe others room. This •will extra allow batteries emergency for the personnelabove tools to quickly outside the immediate area that you have a safe room. free you if the exit from your safe room becomes blocked• wrench by debris.(to turn y offou gasshould and alsowater) prepare an This will allow emergency personnel to quickly free • insect repellent and sunscreen you emergencyif the exit from supply your kit safe and room either becomes keep blockedit in your safe room or be ready to bring it with you if you by debris.need toYou evacuate should also your prepare home. an Some emergency of the items that• the personal emergency hygiene supply items suchkit should as hand include wipes andare: supply kit and either keep it in your safe room or be toilet paper readyn toAn bring adequate it with you supply if you of needwater to for evacuate each person your in your home or small business home. Some of the items that the emergency supply kit 1 The National Oceanic and Atmospheric Administra tion should include(1 gallon are: per person per day) (NOAA) Weather Radio (NWR) is a nationwide network of radio stations broadcasting continuous weather information • Ann adequate Non-perishable supply of water foods for that each do person not have in your to be prepareddirectly orfrom cooked a nearby (if Nationalthese include Weather canned Service (NWS) home orgoods, small rememberbusiness (1 togallon bring per a manualperson per can day) opener)office. NWR broadcasts NWS warnings, watches, forecasts, and other hazard information 24 hours a day, as well as • Non-perishable foods that do not have to be prepared post-event information for all types of hazards, both natural or 10cooked (if these include cannedTaking goods,shelTer rememberfrom The sT orm: BUILDINGand technological. A SAFE ROOM NOAA FOR YOUR Weather HOME Radios OR SMALL are available BUSINESS at to bring a manual can opener) electronics stores across the country and range in cost from $25 up to $100 or more, depending on the quality of the • Disposable eating utensils, plates, cups, paper towels, receiver and number of features. The NWS does not endorse 2 ABC refers to fires originating from three types of sources: A etc. any particular make or model of receiver. 12 Taking shelTer from The sTorm: BUILDING- paper, A SAFE wood, ROOM or fabric; FOR YOUR B - gasolineHOME OR or SMALL oil; or B USINESSC - electrical.

68 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 69 seCTion i: UNDERSTANDING THE HAZARDS ThIrd EdITIon

68 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 69 seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon

ThIrd EdITIon Buildings that fail under the effects of extreme winds often appear to have exploded, giving rise to the misconception that the damage is Section II: caused by unequal atmospheric or wind pressures inside and outside the building. This misconception Planning Your Safe has led to the myth that, during an extreme-wind event, the windows Room and doors in a building should be opened to equalize the pressure. In fact, opening a window or door Now that you better understand your risk from a tornado or hurricane, you can work with your allows wind to enter a building builder/contractor to build a safe room to provide near-absolute protection for you, your family, and increases the risk of building 2" x 6" missile penetrating a refrigerator, midwest tornadoes of or employees from these extreme windstorms. This section describes how extreme winds can failure. May 3, 1999 damage a building, explains the basis of the safe room designs presented in this publication, and shows where you can build a safe room in your home or small business. Damage can also be caused by flying debris (referred to as windborne missiles). If wind speeds are extreme enough, missiles can be thrown at a building with enough force to penetrate or Building Damage perforate windows, walls, or the roof. For example, SECTIONExtreme II |winds PLANNING can cause severalYOUR kinds of damage masonryan wall, object which such typically as a 2"has x hollow4" wood cells stud between weighing 15 to a building. To understand what happens when reinforcedpounds, cells, will when be perforated carried by unless a 250-mph it has been wind, can have SAFE ROOM designed and constructed to resist debris impact during extreme winds strike, you must first understand a horizontal speed of 100 mph, which is enough Now that you better understand your risk from a tornado or extreme winds. Because missiles can severely damage that tornado and hurricane winds are not constant. force to penetrate or perforate most common building hurricane, you can work with your builder/contractor to build and even perforate windows, walls, and roofs, they a safe roomWind to speeds, provide near-absoluteeven in these protection extreme-wind for you, events, your threatenmaterials not only buildings used in homesbut the today.occupants Even as a well. reinforced family, orrapidly employees increase from and these decrease. extreme Anwindstorms. obstruction, This such section masonry wall, which typically has hollow cells describesas how a home, extreme in thewinds path can of damage the wind a building, causes theexplains wind the between reinforced cells, will be perforated unless it basis of tothe change safe room direction. designs This presented change in thisin wind publication, direction and has been designed and constructed to resist debris shows where you can build a safe room in your home or small impact during extreme winds. Because missiles can business.increases pressure on parts of the home. The combination of increased pressures and fluctuating severely damage and even perforate windows, walls, wind speeds creates stress on the home that and roofs, they threaten not only buildings but the Palm tree tree pierced pierced by byplywood plywood missile, missile, Hurricane Building Damage occupants as well. Hurricane Andrew frequently causes connections between building Andrew Extremecomponents winds can cause to fail. several kinds of damage to a building. definition To understand what happens when extreme winds strike, you In this publication, missiles may be said to penetrate but not perforate the walls or roof of a safe room. must firstFor understandexample, thethat roof tornado covering, and roofhurricane deck, windsor wall are siding For example, if a missile penetrates an exterior element of the safe room, this means the missile broke or damaged the exterior surface, but has not entered the safe room protected area. It is quite common for smaller not constant.can be Wind pulled speeds, off and even the in windows these extreme-wind can be pushed events, into rapidly increase and decrease. An obstruction, such as a home, missiles such as small stones, branches,In this publication, and other lighter missiles missiles may beto penetratesaid to penetrate or imbed but themselves not perforate into the the in the pathor suctioned of the wind out causes of a building. the wind Figure to change II-1 showsdirection. how exterior of the safe room and thiswalls is acceptable. or roof of aHowever, safe room. the For safe example, room walls, if a missileroof, and penetrates protected openingsan exterior This changeextreme in wind winds direction can affect increases a building pressure and on helps parts explain of the must not allow a missile to perforateelement these of systemsthe safe and room, allow this the means missile the to entermissile into broke the safe or damagedroom. When the home. Thewhy combination these winds of cause increased buildings pressures to fail. and When fluctuating wind is any portion of the safe room exteriorexterior is damaged surface, such but hasthat nota missile, entered or portionthe safe thereof, room protectedenters the protectedarea. It is area, the safeD roomefini exteriorTion has been perforated and this is not acceptable. wind speedsallowed creates to enter stress a on building the home through that frequentlya broken window, causes seCTion ii: PLANNINGquite common YOUR SAFEfor smaller ROOM missiles such as small stones, branches,ThIrd andEdITI on connections between building components to fail. seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon door, or roof section, that wind will act on the inside of a other lighter missiles to penetrate or imbed themselves into the exterior of the safe room and For example,building the much roof covering, like air will roof act deck, when or forced wall siding into a can balloon; be this is acceptable. However,Basis theof s safeafe rroomoom walls, roof, and protected openings must not allow pulled off and the windows can be pushed into or suctioned out Basis ofBasis Safe Room of s Designafe room it will push (or pull) on the walls and roof of the building a missile to perforate theseDesign systems and allow the missile to enter into the safe room. When of a building. Figure II-1 shows how extreme winds can affect a The purposeDesign of a safe room is to provide a space from the inside. These forces within the building, added any portion of the safe Theroom purpose exterior of a safeis damaged room is to such that a missile, or portion thereof, enters building and helps explain why these winds cause buildings to where you, your family, or employees can survive fail. Whento the wind wind is allowed forces that to enter are still a building acting on through the outside a broken of a Thethe purpose protected of a area, safe theroomprovide safe is to rooma space exterior where you, has your been perforated and this is not acceptable. a tornado or hurricane with little or family,no injury. or employees can survive window, door, or roof section, that wind will act on the inside provide a space where you, your building, often result in failure of the building because it For tornado-prone areas, you shoulda locatetornado youror hurricane with little of a building much like air will act when forced into a balloon; was not designed to resist the forces acting on both the Figure II-1. Effect of extreme winds on safe roomfamily, so that or you employees can reach can it as surviveor quickly no injury. asFor tornado-prone it will push (or pull) on the walls and roof of the building from Figure II-1. Effect of extreme winds on building 14 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS inside and the outside of the building building roof and walls possibly afrom tornado all parts or hurricaneof your home withareas, or little business. you should locate your the inside. These forces within the building, added to the wind roof and walls In hurricane-prone areas, the safe roomsafe roomshould so that you can reach seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon or no injury. For tornado-prone forces that are still acting on the outside of a building, often not be built where it can be floodedit asduring quickly a as possibly from all areas, you should locate yourparts of your home or business. result inTaking failure shel of Ttheer from building The s Tbecauseorm: BUILDING it was A notSAFE designed ROOM FOR toYOUR HOME OR SMALL BUSINESS 13 hurricane. Your safe room should be readily resist the forces acting on both the inside and In hurricane-prone areas, the accessiblesafe from room all parts so that of your you homecan reach or small the outsideBuildings of the building.that fail under Buildings the thateffects safe room should not be built business itand as shouldquickly be as free possibly of clutter. from To all provide fail underof the extreme effects winds of extreme often winds appear often to where it can be flooded during near-absoluteparts protectionof your home for the or occupantsbusiness.a hurricane. during your safe room appear to have exploded, giving rise to the have exploded, giving rise to the extreme windstorms, the safe room shouldmust be readily accessible from misconception that the damage is caused by In hurricane-prone areas, the misconception that the damage is adequately anchored to the home’s allfoundation parts of your home or small Missile (debris) launcher, Wind Engineering Research Center (WERC), unequal atmospheric or wind pressures inside safe room should not be built Texas Tech University caused by unequal atmospheric or to resist overturning and uplift. Thebusiness connections and should Missile be free of (debris) launcher, Wind Engineering Research and outside the building. This misconception between whereall parts it ofcan the be safe flooded room mustduringclutter. be To strong provide near-absoluteCenter (WERC), Texas Tech University has led towind the pressuresmyth that, insideduring andan extreme- outside protection for the occupants during extreme enough toa hurricane.resist failure, your and safe the roomwalls, roof, and wind event,the building.the windows This and misconception doors in a windstorms, the safe room must be adequately door mustshould resist beperforation readily accessible by windborneanchored from missiles. to the home’s foundation to resist buildinghas should led beto openedthe myth to that, equalize during the an Missile (debris) launcher, Wind Engineering Research Center (WERC), pressure. In fact, opening a window or door all parts of your home or smalloverturning and uplift. The connections between extreme-wind event, the windows Extensive testing by Texas Tech University and Texas Tech University allows wind to enter a building and increases other windbusiness engineering and should research be facilities freeall parts of has of the shown safe room must be strong enough to resist failure, and the walls, roof, and door must the risk ofand building doors failure.in a building should be that walls, ceilings, and doors commonly used in 2” x 4” wood clutter. To provide near-absoluteresist perforation by windborne missiles. opened to equalize the pressure. stud launched at Damage can also be caused by flying debris buildingprotection construction for to the meet occupants minimum during building extreme 100 mph pierces (referredIn to fact, as windborne opening amissiles). window If or wind door code requirements for standard buildingExtensive construction testing by Texas Tech University and other windstorms, the safe room must be adequately unreinforced speeds areallows extreme wind enough, to enter missiles a building can be cannot withstand the impact of missileswind engineeringcarried research facilities has shown that anchored to the home’s foundation to resist masonry wall, thrown atand a building increases with the enough risk of force building to by extreme winds. The safe room designswalls, ceilings, in this and doors commonly used in building 2" x 6" missile penetrating a refrigerator, midwest tornadoes construction to meet minimum WERC,building code Texas Tech penetrate or perforate windows, walls, or the 2" x 6" missile penetrating a refrigerator, midwest tornadoes of publicationoverturning account for and these uplift. findings The connections by specifying between failure. of May 3, 1999 requirements for standard building constructionUniversity roof. For example, an object such as a 2” x 4” May 3, 1999 buildingall materials parts of and the combinations safe room must of building be strong enough materials that will resist perforation cannotby missiles withstand in the impact of missiles carried wood stud weighing 15 pounds, when carried to resist failure, and the walls,by extreme roof, winds. and The door safe must room designs in this Damage can also be caused by flying debris (referred to as windborne missiles). If wind speeds extreme winds. by a 250-mph wind, can have a horizontal speed of 100 mph, resist perforation by windbornepublication missiles. account for these findings by specifying which is areenough extreme force enough, to penetrate missiles or perforate can be most thrown common at a building with enough force to penetrate or Most homes, even new ones constructedbuilding according materials and combinations of building buildingperforate materials usedwindows, in homes walls, today. or the Even roof. a reinforcedFor example, to current building codes, do not providematerials adequate that will resist perforation by missiles in Extensive testing by Texasextreme Tech winds.University and other an object such as a 2" x 4" wood stud weighing 15 2” x 4” wood stud launched at 100 mph pierces 70 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTUREwind engineering research facilities has shownTaking that Shelter from the Storm:unreinforced Building masonry a wall,Safe WERC, Room Texas | Tech71 pounds, when carried by a 250-mph wind, can have Most homes, even new ones constructed according walls, ceilings, and doors commonly used in building University a horizontal speed of 100 mph, which is enough to current building codes, do not provide adequate construction to meet minimumprotection building for occupants code seeking life-safety protection from tornadoes. Homes built to the force to penetrate or perforate most common building requirements for standardmodern building building construction codes in hurricane-prone areas, such as windborne debris regions better resist materials used in homes today. Even a reinforced wind forces and windborne debris impacts from hurricanes. However, a tornado or hurricane can cannot withstand the impact of missiles carried masonry wall, which typically has hollow cells by extreme winds. The safeTaking room shelTer designs from The sT orm:in thisBUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 15 between reinforced cells, will be perforated unless it publication account for these findings by specifying has been designed and constructed to resist debris building materials and combinations of building impact during extreme winds. Because missiles can materials that will resist perforation by missiles in severely damage and even perforate windows, walls, extreme winds. and roofs, they threaten not only buildings but the 2” x 4” wood stud launched at 100 mph pierces Palm tree pierced by plywood missile, Hurricane occupants as well. unreinforced masonry wall, WERC, Texas Tech Andrew Most homes, even new ones constructed according University to current building codes, do not provide adequate protection for occupants seeking life-safety protection from tornadoes. Homes built to the modern building codes in hurricane-prone areas, such as windborne debris regions better resist In this publication, missiles may be said to penetrate but not perforate the wind forces and windborne debris impacts from hurricanes. However, a tornado or hurricane can walls or roof of a safe room. For example, if a missile penetrates an exterior element of the safe room, this means the missile broke or damaged the Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 15 DefiniTion exterior surface, but has not entered the safe room protected area. It is quite common for smaller missiles such as small stones, branches, and other lighter missiles to penetrate or imbed themselves into the exterior of the safe room and this is acceptable. However, the safe room walls, roof, and protected openings must not allow a missile to perforate these systems and allow the missile to enter into the safe room. When any portion of the safe room exterior is damaged such that a missile, or portion thereof, enters the protected area, the safe room exterior has been perforated and this is not acceptable.

14 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon

14 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS protection for occupants seeking life-safety protection Designing a building, or portion of a building, to safe room, the recommended amount of floor area Foundation Types from tornadoes. Homes built to the modern building resist damage from more than one natural hazard per person (standing or seated, not wheelchair or codes in hurricane-prone areas, such as windborne requires different, sometimes competing, approaches. bedridden) varies from 7 to 20 square feet, depending Homes and other buildings vary in construction type debris regions better resist wind forces and windborne For example, building a structure on an elevated upon the classification of the safe room. The as well as foundation type. Buildings constructed may debris impacts from hurricanes. However, a tornado or foundation to raise it above expected flood levels can minimum sizing requirement set forth in the ICC- have heavy walls systems, such as masonry or concrete, or they may have light walls systems constructed hurricane can cause wind and windborne debris loads increase its vulnerability to wind and seismic damage. 500 for residentialseCTion hurricane ii: PLANNING shelters YOUR is 7 squareSAFE ROOM feet ThIrd EdITIon on a home or small business that are much greater These design approaches need to be thoroughly per occupant, while for small community shelters 20 from wood framing, metal stud framing, or structural than those on which building code requirements are considered. In flood-prone areas, careful attention square feet per occupant is specified. Necessities, such insulated panels (SIPs). Regardless of the structure based. Only specially designed and constructed safe should be given to the warning time, velocity, as waterfoundation and toilet facilities,Types should also be provided above, the following types of foundations may be rooms, which are voluntarily built above the minimum depth, and duration of floodwaters. These flooding in the small community safe rooms to maintain suitable for the installation of a safe room: Homes and other buildings vary in construction type as well as foundation type. Buildings code requirements of the IBC and IRC to the criteria characteristics can have a significant bearing on the compliance with the FEMA 361 criteria and ICC- 500 • Basement of this publication, FEMA 361, or the ICC-500, offer design and possibly even the viability of a safe room. requirements.constructed The may safe have room heavy designs walls in systems, this guide such as masonry or concrete, or they may have light life-safety occupant protection during a tornado or Your local building official or licensed professional maywalls have systems a minimum constructed floor area from of wood48 square framing, feet andmetal stud• Slab-on-grade framing, or structural insulated panels strong hurricane. The prescriptive designs provided in engineer or architect can provide you with information a wall(SIPs). length Regardless of 6 feet. ofA safethe structureroom of that above, size theused following • Crawlspacetypes of foundations or pile (however, may be prescriptive suitable for solutions this publication provide near-absolute protection from about other natural hazards that affect your area and forthe hurricane installation protection of a safe could room: accommodate up to for pile foundations are not provided in the drawings winds and windborne debris associated with tornadoes can also recommend appropriate designs. six people in reasonable comfort while maintaining included in this publication) or hurricanes. compliancen Basement with the FEMA 361 criteria and ICC-500 requirements. The maximum floor dimensions in the The safe room designs provided in this publication are Basement Foundation Applications Safe Room Size safe roomn designsSlab-on-grade provided in this guide are shown to based on wind speeds that are rarely exceeded in the be 14 feet by 14 feet square, providing 196 square feet A home on a basement foundation (see Figure II-2) United States. Therefore, a safe room built according The amount of floor area per person that your safe n Crawlspace or pile (however, prescriptive solutions for pile foundations are not provided in of safe room space. This amount of space could provide is usually built on a foundation constructed of cast- to these designs is expected to withstand the forces room must provide depends partly on the type of the drawings included in this publication) safe room protection for nine occupants at the ICC-500 in-place concrete or concrete masonry units (CMUs). imposed on it by extreme winds without failing; this windstorm from which the safe room is intended to square footage requirements for a small community Most concrete foundations are reinforced with steel statement applies to both materials and connections protect you. Tornadoes are not long-lasting storms, so Basement foundation applications hurricane shelter. If you plan to build a safe room with bars or straps, but many CMU foundation walls have used within the safe room. The intent of the designs if you are relying on your safe room only for tornado anyA wallhome longer on a than basement 14 feet, foundation or with a wall(see height Figure II-2) is nousually steel reinforcement.built on a foundation The framing constructed for the floor above is not to produce a safe room that will always remain protection, you will not need to stay in the safe room greaterof cast-in-place than 8 feet, concreteconsult a orlicensed concrete professional masonry units (CMUs).the basement Most concrete is supported foundations by the exterior are foundation completely undamaged, but rather a safe room that for as long a time-frame as you would for a hurricane. engineerreinforced or architect. with steel bars or straps, but many CMU foundationwalls and walls sometimes have no by steela center reinforcement. beam. will enable its occupants to survive an extreme As a result, comfort is not of great concern, and a windstorm with minor or no injuries. safe room that provides at least 5 square feet of floor The framing for the floor above the basement is area per person (note that wheelchair and bedridden supported by the exterior foundation walls It is very important to note that predicting the exact occupants will require more space) will be big enough. and sometimes by a center beam. strength of tornadoes and hurricanes is impossible. This allocation of space per occupant also meets the That is another reason why the safe room designs in minimum sizing requirements set forth in the ICC-500 this publication are based on extreme-wind speeds and for residential and small community tornado shelters. why the primary consideration is life safety. When the safe room is intended to provide near- absolute protection from storms such as hurricanes, note which can last for 24 hours or more, the comfort of Figure II-2. the occupants should be considered. For this type of Cross-section: typical basement This publication provides FEMA safe room foundation, with safe room designs that meet or exceed the minimum shelter design requirements from the ICC-500 Storm note Shelter Standard. The safe room designs in this The safe room designs in this publication are publication are applicable for both tornado and applicable for any on-site construction. However, hurricane hazards for the residential shelter and in a modular home, the safe room location would Figure II-2. small community shelter (<16 occupants) design be limited to the basement or the below-ground Cross-section: typical criteria identified in the ICC-500. The safe room module unless a separate foundation was designed basement foundation, design wind speed used is 250 mph and it has been and installed for the safe room. A modular home with safe room designed as a “partially enclosed building” per ASCE is a home constructed of modular units that have 7 so as to meet the requirements of both residential been built elsewhere, brought to the site, and and community safe rooms for tornado and installed on a permanent foundation. hurricane hazards. Further, the missile resistance is based upon the 15-lb 2”x4” board missile traveling horizontally at 100 mph (again, the most restrictive note criteria for both tornado and hurricane hazards). Consult FEMA 361 or the ICC-500 for guidelines For additional design criteria and information for and requirements on how to identify the net residential safe rooms, see the notes on the safe usable floor space for a safe room design from the room plans in this publication and the design publication if it is to be used as a small community requirements for residential safe rooms in Chapter safe room. Hard fixtures (sinks, bathtubs, etc.) and 3 of FEMA 361, Design and Construction Guidance for furnishings reduce the square footage within a safe Community Safe Rooms. room that is available for protecting occupants.

72 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE18 Taking shelTer from The sTorm: TakingBUILDING Shelter A SAFE ROOMfrom FOR the YOUR Storm: HOME Building OR SMALL a BSafeUSINESS Room | 73 protection for occupants seeking life-safety protection Designing a building, or portion of a building, to safe room, the recommended amount of floor area Foundation Types from tornadoes. Homes built to the modern building resist damage from more than one natural hazard per person (standing or seated, not wheelchair or codes in hurricane-prone areas, such as windborne requires different, sometimes competing, approaches. bedridden) varies from 7 to 20 square feet, depending Homes and other buildings vary in construction type debris regions better resist wind forces and windborne For example, building a structure on an elevated upon the classification of the safe room. The as well as foundation type. Buildings constructed may debris impacts from hurricanes. However, a tornado or foundation to raise it above expected flood levels can minimum sizing requirement set forth in the ICC- have heavy walls systems, such as masonry or concrete, or they may have light walls systems constructed hurricane can cause wind and windborne debris loads increase its vulnerability to wind and seismic damage. 500 for residentialseCTion hurricane ii: PLANNING shelters YOUR is 7 squareSAFE ROOM feet ThIrd EdITIon on a home or small business that are much greater These design approaches need to be thoroughly per occupant, while for small community shelters 20 from wood framing, metal stud framing, or structural than those on which building code requirements are considered. In flood-prone areas, careful attention square feet per occupant is specified. Necessities, such insulated panels (SIPs). Regardless of the structure based. Only specially designed and constructed safe should be given to the warning time, velocity, as waterfoundation and toilet facilities,Types should also be provided above, the following types of foundations may be rooms, which are voluntarily built above the minimum depth, and duration of floodwaters. These flooding in the small community safe rooms to maintain suitable for the installation of a safe room: Homes and other buildings vary in construction type as well as foundation type. Buildings code requirements of the IBC and IRC to the criteria characteristics can have a significant bearing on the compliance with the FEMA 361 criteria and ICC- 500 • Basement of this publication, FEMA 361, or the ICC-500, offer design and possibly even the viability of a safe room. requirements.constructed The may safe have room heavy designs walls in systems, this guide such as masonry or concrete, or they may have light life-safety occupant protection during a tornado or Your local building official or licensed professional maywalls have systems a minimum constructed floor area from of wood48 square framing, feet andmetal stud• Slab-on-grade framing, or structural insulated panels strong hurricane. The prescriptive designs provided in engineer or architect can provide you with information a wall(SIPs). length Regardless of 6 feet. ofA safethe structureroom of that above, size theused following • Crawlspacetypes of foundations or pile (however, may be prescriptive suitable for solutions this publication provide near-absolute protection from about other natural hazards that affect your area and forthe hurricane installation protection of a safe could room: accommodate up to for pile foundations are not provided in the drawings winds and windborne debris associated with tornadoes can also recommend appropriate designs. six people in reasonable comfort while maintaining included in this publication) or hurricanes. compliancen Basement with the FEMA 361 criteria and ICC-500 requirements. The maximum floor dimensions in the The safe room designs provided in this publication are Basement Foundation Applications Safe Room Size safe roomn designsSlab-on-grade provided in this guide are shown to based on wind speeds that are rarely exceeded in the be 14 feet by 14 feet square, providing 196 square feet A home on a basement foundation (see Figure II-2) United States. Therefore, a safe room built according The amount of floor area per person that your safe n Crawlspace or pile (however, prescriptive solutions for pile foundations are not provided in of safe room space. This amount of space could provide is usually built on a foundation constructed of cast- to these designs is expected to withstand the forces room must provide depends partly on the type of the drawings included in this publication) safe room protection for nine occupants at the ICC-500 in-place concrete or concrete masonry units (CMUs). imposed on it by extreme winds without failing; this windstorm from which the safe room is intended to square footage requirements for a small community Most concrete foundations are reinforced with steel statement applies to both materials and connections protect you. Tornadoes are not long-lasting storms, so Basement foundation applications hurricane shelter. If you plan to build a safe room with bars or straps, but many CMU foundation walls have used within the safe room. The intent of the designs if you are relying on your safe room only for tornado anyA wallhome longer on a than basement 14 feet, foundation or with a wall(see height Figure II-2) is nousually steel reinforcement.built on a foundation The framing constructed for the floor above is not to produce a safe room that will always remain protection, you will not need to stay in the safe room greaterof cast-in-place than 8 feet, concreteconsult a orlicensed concrete professional masonry units (CMUs).the basement Most concrete is supported foundations by the exterior are foundation completely undamaged, but rather a safe room that for as long a time-frame as you would for a hurricane. engineerreinforced or architect. with steel bars or straps, but many CMU foundationwalls and walls sometimes have no by steela center reinforcement. beam. will enable its occupants to survive an extreme As a result, comfort is not of great concern, and a windstorm with minor or no injuries. safe room that provides at least 5 square feet of floor The framing for the floor above the basement is area per person (note that wheelchair and bedridden supported by the exterior foundation walls It is very important to note that predicting the exact occupants will require more space) will be big enough. and sometimes by a center beam. strength of tornadoes and hurricanes is impossible. This allocation of space per occupant also meets the That is another reason why the safe room designs in minimum sizing requirements set forth in the ICC-500 this publication are based on extreme-wind speeds and for residential and small community tornado shelters. why the primary consideration is life safety. When the safe room is intended to provide near- absolute protection from storms such as hurricanes, note which can last for 24 hours or more, the comfort of Figure II-2. the occupants should be considered. For this type of Cross-section: typical basement This publication provides FEMA safe room foundation, with safe room designs that meet or exceed the minimum shelter design requirements from the ICC-500 Storm note Shelter Standard. The safe room designs in this The safe room designs in this publication are publication are applicable for both tornado and applicable for any on-site construction. However, hurricane hazards for the residential shelter and in a modular home, the safe room location would Figure II-2. small community shelter (<16 occupants) design be limited to the basement or the below-ground Cross-section: typical criteria identified in the ICC-500. The safe room module unless a separate foundation was designed basement foundation, design wind speed used is 250 mph and it has been and installed for the safe room. A modular home with safe room designed as a “partially enclosed building” per ASCE is a home constructed of modular units that have 7 so as to meet the requirements of both residential been built elsewhere, brought to the site, and and community safe rooms for tornado and installed on a permanent foundation. hurricane hazards. Further, the missile resistance is based upon the 15-lb 2”x4” board missile traveling horizontally at 100 mph (again, the most restrictive note criteria for both tornado and hurricane hazards). Consult FEMA 361 or the ICC-500 for guidelines For additional design criteria and information for and requirements on how to identify the net residential safe rooms, see the notes on the safe usable floor space for a safe room design from the room plans in this publication and the design publication if it is to be used as a small community requirements for residential safe rooms in Chapter safe room. Hard fixtures (sinks, bathtubs, etc.) and 3 of FEMA 361, Design and Construction Guidance for furnishings reduce the square footage within a safe Community Safe Rooms. room that is available for protecting occupants.

72 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE18 Taking shelTer from The sTorm: TakingBUILDING Shelter A SAFE ROOMfrom FOR the YOUR Storm: HOME Building OR SMALL a BSafeUSINESS Room | 73 seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon In a new or existing home with a basement, the Slab-on-Grade Applications separate from the structure of Figure II-3. safe room should be built in the basement. You can the home. Keeping the walls Cross-section: typical slab-on- A slab-on-grade home or commercial building (see build the safe room as an entirely separate structure separateFigure makes II-3. it possible grade foundation, Figure II-3) is built on a concrete slab that is installed with its own walls, or you can use one or more of for theCross-section: safe room to typical remain slab-on-grade foundation, with safe room on compacted or natural soil. The concrete may be the basement walls as walls of the safe room. If you standingwith evensafe roomif portions reinforced with steel that helps prevent cracking and use the existing basement walls, they will have to be of the home around it are bending. If you are building a new slab-on-grade home specially reinforced. Typical reinforcement techniques destroyed by extreme winds. and want to install a safe room (of any material or used in residential basement walls will not provide type), it is recommended that the slab or foundation • If you are creating your sufficient protection from missiles and resistance to beneath the safe room wall be reinforced and thicker safe room by modifying a extreme-wind loads. In new construction, your builder/ to ensure proper support and resistance to all loads bathroom, closet, or other contractor can reinforce the walls near the safe room (gravity and wind loads). The thickened slab will act as interior room with wood- during the construction of your home. Reinforcing the a footing beneath the walls of the safe room to provide frame walls, the existing basement walls of an existing home is not practical. structural support. It will also help anchor the safe walls and ceiling must be The likelihood of missiles entering the basement is room so that it will stay in place during an extreme- retrofitted or replaced with lower than for above-ground areas; however, there is wind event, even if the rest of the home is destroyed. walls and a ceiling resistant a significant chance that missiles or falling debris will to the impact of windborne In an existing home, removing part of the slab and enter the basement through an opening left when missiles and other effects of replacing it with a thickened section to support a safe a window, a door, or the first floor above has been extreme winds. In most cases, room would involve extensive effort and disruption torn off by extreme winds. Therefore, your basement this means removing the inside the home. Some safe room designs presented safe room must have its own reinforced ceiling; the sheathing, such as drywall or in the drawings will require a footing to be placed basement ceiling (the first floor above) cannot be used plaster, on either the inside, due to the weight of the safe room itself, but others as the ceiling of the safe room. The safe room designs outside, or both sides of the may be secured to an existing slab provided it has provided have considered that large, heavy loading walls and ceiling. Where reinforcing steel in the concrete. Therefore, building from debris may be experienced by the safe rooms possible, it is recommended a safe room with concrete or concrete masonry when a surrounding structure may collapse during an that the shelter be built as walls in an existing slab-on-grade home may not be extreme-wind event. The roof decks of these safe rooms a “new room” within the practical unless the existing slab can be shown to have are designed to limit the damage that may be induced existing room in order to reinforcement adequate to support the safe room. If from these debris sources. Although the building may isolate the shelter from the reinforcement can be shown to be present, the designs collapse around the safe room, it is still appropriate to home structure. provided in these plans may be retrofitted to certain install the safe room in the basement. using the floor system of the structure itself. In this reinforced slabs. Similarly, a wood-frame safe room • If you intend to build a safe room with concrete or option, the safe room has a separate concrete slab floor The least expensive type of safe room that can be built may be constructed atop an existing, reinforced slab concrete masonry walls, a section of your existing Crawlspace or Pile applications installed on top of earth fill and must be supported by in a basement is a lean-to safe room, which is built because its walls are not as heavy and do not require slab floor may have to be removed and replaced with steel reinforced concrete or CMU foundation walls. The in the corner of the basement and uses two basement the support of a thickened slab; however, these lighter a thickerA home slab. Asbuilt noted on a above, crawlspace if this is(see necessary Figure it II-4) usually has a floor constructed of wood framing. floor system may be designed as open and elevated, but walls. The lean-to safe room uses the fewest materials, safe room designs are vulnerable to displacement by may meanAlong the its retrofitperimeter, may the not floor be practical is supported in the by the exterior foundation walls. The interior part of that design option is difficult to develop a prescriptive requires the least amount of labor, and can be built wind loads. A wood-frame safe room can be created existing home. the floor is supported by beams that rest on a foundationsolution for andwall thereforeor individual is not piers. provided Crawlspace in this more quickly than other types of basement safe rooms from an existing room, such as a bathroom or closet, foundation walls may be concrete, but are usuallypublication. constructed An fromalternative blocks approach, of concrete which masonry may be (see drawings B-01 and B-02). or built as a new room in an open area in the home, unit (CMU). They are often unreinforced and thereforemore economical, provide little is toresistance build an exteriorto the stresses safe room on a such as a garage. Whenever an existing slab is used as Crawlspace or Pile Applications In general, it is easier to add a basement safe room slab-on-grade foundation adjacent to an outside wall of the foundation for a safe room, a structural engineer caused by extreme winds. during the construction of a new home than to retrofit A home built on a crawlspace (see Figure II-4) usually the home and provide access through a door installed should evaluate the adequacy of the slab to resist the the basement of an existing home. If you plan to add has a floor constructed of wood framing. Along its in that wall. wind loads acting on the safe room. a basement safe room as a retrofitting project, keep the perimeter,Building the floor a safe is supported room inside by thea home exterior on a crawlspace foundation is more difficult than building following points in mind: You can also build a safe room as an addition to the foundationa shelter walls. inside The interior a home part on of a thebasement floor is or slab-on-gradeVentilation foundation. in the area Thebelow main the floorreason of isthe that home outside of a slab-on-grade home. This type of safe supportedthe byentire beams safe that room, rest onincluding a foundation its floor, wall must beis separatealso an important from the issue.framing The ofwood-framed the home or floor the of • You must be able to clear out an area of the basement room must not only have proper footings, but also a or individual piers. Crawlspace foundation walls may a home on a crawlspace foundation is typically held large enough for the safe room. be concrete,entire but floor are usuallysystem constructedand foundation from ofblocks the home 18will to be30 required inches above to be the constructed ground by tothe support foundation the watertight roof. Because a safe room built as an outside extreme-wind loads acting on the safe room. In Figure II-4, a safe room is built inside the home or • Unless the exterior basement walls contain steel addition will be more susceptible to the impact of of concrete masonry unit (CMU). They are often walls for compliance with the building code. The space reinforcement as shown on the design drawings missiles, it should not be built of wood framing alone. unreinforcedcommercial and therefore building provide without little using resistance the floor to systembelow of thethe floor structure is designed itself. Into thisallow option, air to theflow safe through the stresses caused by extreme winds. provided with this publication, these walls cannot be Instead, it should be built of concrete or concrete room has a separate concrete slab floor installedso thaton top the offloor earth framing fill and will mustnot becomebe supported too damp. by It is important that the installation of the safe room not used as safe room walls since they are not reinforced masonry. Access to this type of safe room can be Buildingsteel a safe reinforced room inside concrete a home or on CMU a crawlspace foundation walls. The floor system may be designed as open block this air flow. to resist damage from missiles and uplift from provided through an existing window or door in an foundationand elevated,is more difficult but that than design building option a shelter is difficult to develop a prescriptive solution for and therefore extreme winds. exterior wall of the home. inside ais home not provided on a basement in this or publication. slab-on-grade An alternativeIn approach, general, it which is much may easier be moreto build economical, a safe room is inside to foundation. The main reason is that the entire safe • Exterior basement walls that are used as safe room In general, it is easier to add a safe room during the a new crawlspace home than in an existing crawlspace room, includingbuild an exterior its floor, safe must room be separate on a slab-on-grade from foundation adjacent to an outside wall of the home walls must not contain windows, doors, or other construction of a new slab-on-grade home than to home. If you plan to add a safe room to an existing the framingand provide of the home access or the through entire a floor door system installed in that wall. openings in the area providing protection. retrofit an existing slab-on-grade home. If you plan crawlspace home as a retrofitting project, keep the and foundation of the home will be required to be to add a safe room to a slab-on-grade home as a following points in mind: • The safe room must be built with its own ceiling, so constructedTaking to shel supportTer from the The extreme-wind sTorm: BUILDING loads A SAFE acting ROOM FOR YOUR HOME OR SMALL BUSINESS retrofitting project, keep the following points in mind: 21 that the occupants will be protected from missiles on the safe room. In Figure II-4, a safe room is built • The safe room must have a separate foundation. and falling debris. • The walls of the safe room must be completely inside the home or commercial building without Building the foundation inside the home would

74 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 75 seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon In a new or existing home with a basement, the Slab-on-Grade Applications separate from the structure of Figure II-3. safe room should be built in the basement. You can the home. Keeping the walls Cross-section: typical slab-on- A slab-on-grade home or commercial building (see build the safe room as an entirely separate structure separateFigure makes II-3. it possible grade foundation, Figure II-3) is built on a concrete slab that is installed with its own walls, or you can use one or more of for theCross-section: safe room to typical remain slab-on-grade foundation, with safe room on compacted or natural soil. The concrete may be the basement walls as walls of the safe room. If you standingwith evensafe roomif portions reinforced with steel that helps prevent cracking and use the existing basement walls, they will have to be of the home around it are bending. If you are building a new slab-on-grade home specially reinforced. Typical reinforcement techniques destroyed by extreme winds. and want to install a safe room (of any material or used in residential basement walls will not provide type), it is recommended that the slab or foundation • If you are creating your sufficient protection from missiles and resistance to beneath the safe room wall be reinforced and thicker safe room by modifying a extreme-wind loads. In new construction, your builder/ to ensure proper support and resistance to all loads bathroom, closet, or other contractor can reinforce the walls near the safe room (gravity and wind loads). The thickened slab will act as interior room with wood- during the construction of your home. Reinforcing the a footing beneath the walls of the safe room to provide frame walls, the existing basement walls of an existing home is not practical. structural support. It will also help anchor the safe walls and ceiling must be The likelihood of missiles entering the basement is room so that it will stay in place during an extreme- retrofitted or replaced with lower than for above-ground areas; however, there is wind event, even if the rest of the home is destroyed. walls and a ceiling resistant a significant chance that missiles or falling debris will to the impact of windborne In an existing home, removing part of the slab and enter the basement through an opening left when missiles and other effects of replacing it with a thickened section to support a safe a window, a door, or the first floor above has been extreme winds. In most cases, room would involve extensive effort and disruption torn off by extreme winds. Therefore, your basement this means removing the inside the home. Some safe room designs presented safe room must have its own reinforced ceiling; the sheathing, such as drywall or in the drawings will require a footing to be placed basement ceiling (the first floor above) cannot be used plaster, on either the inside, due to the weight of the safe room itself, but others as the ceiling of the safe room. The safe room designs outside, or both sides of the may be secured to an existing slab provided it has provided have considered that large, heavy loading walls and ceiling. Where reinforcing steel in the concrete. Therefore, building from debris may be experienced by the safe rooms possible, it is recommended a safe room with concrete or concrete masonry when a surrounding structure may collapse during an that the shelter be built as walls in an existing slab-on-grade home may not be extreme-wind event. The roof decks of these safe rooms a “new room” within the practical unless the existing slab can be shown to have are designed to limit the damage that may be induced existing room in order to reinforcement adequate to support the safe room. If from these debris sources. Although the building may isolate the shelter from the reinforcement can be shown to be present, the designs collapse around the safe room, it is still appropriate to home structure. provided in these plans may be retrofitted to certain install the safe room in the basement. using the floor system of the structure itself. In this reinforced slabs. Similarly, a wood-frame safe room • If you intend to build a safe room with concrete or option, the safe room has a separate concrete slab floor The least expensive type of safe room that can be built may be constructed atop an existing, reinforced slab concrete masonry walls, a section of your existing Crawlspace or Pile applications installed on top of earth fill and must be supported by in a basement is a lean-to safe room, which is built because its walls are not as heavy and do not require slab floor may have to be removed and replaced with steel reinforced concrete or CMU foundation walls. The in the corner of the basement and uses two basement the support of a thickened slab; however, these lighter a thickerA home slab. Asbuilt noted on a above, crawlspace if this is(see necessary Figure it II-4) usually has a floor constructed of wood framing. floor system may be designed as open and elevated, but walls. The lean-to safe room uses the fewest materials, safe room designs are vulnerable to displacement by may meanAlong the its retrofitperimeter, may the not floor be practical is supported in the by the exterior foundation walls. The interior part of that design option is difficult to develop a prescriptive requires the least amount of labor, and can be built wind loads. A wood-frame safe room can be created existing home. the floor is supported by beams that rest on a foundationsolution for andwall thereforeor individual is not piers. provided Crawlspace in this more quickly than other types of basement safe rooms from an existing room, such as a bathroom or closet, foundation walls may be concrete, but are usuallypublication. constructed An fromalternative blocks approach, of concrete which masonry may be (see drawings B-01 and B-02). or built as a new room in an open area in the home, unit (CMU). They are often unreinforced and thereforemore economical, provide little is toresistance build an exteriorto the stresses safe room on a such as a garage. Whenever an existing slab is used as Crawlspace or Pile Applications In general, it is easier to add a basement safe room slab-on-grade foundation adjacent to an outside wall of the foundation for a safe room, a structural engineer caused by extreme winds. during the construction of a new home than to retrofit A home built on a crawlspace (see Figure II-4) usually the home and provide access through a door installed should evaluate the adequacy of the slab to resist the the basement of an existing home. If you plan to add has a floor constructed of wood framing. Along its in that wall. wind loads acting on the safe room. a basement safe room as a retrofitting project, keep the perimeter,Building the floor a safe is supported room inside by thea home exterior on a crawlspace foundation is more difficult than building following points in mind: You can also build a safe room as an addition to the foundationa shelter walls. inside The interior a home part on of a thebasement floor is or slab-on-gradeVentilation foundation. in the area Thebelow main the floorreason of isthe that home outside of a slab-on-grade home. This type of safe supportedthe byentire beams safe that room, rest onincluding a foundation its floor, wall must beis separatealso an important from the issue.framing The ofwood-framed the home or floor the of • You must be able to clear out an area of the basement room must not only have proper footings, but also a or individual piers. Crawlspace foundation walls may a home on a crawlspace foundation is typically held large enough for the safe room. be concrete,entire but floor are usuallysystem constructedand foundation from ofblocks the home 18will to be30 required inches above to be the constructed ground by tothe support foundation the watertight roof. Because a safe room built as an outside extreme-wind loads acting on the safe room. In Figure II-4, a safe room is built inside the home or • Unless the exterior basement walls contain steel addition will be more susceptible to the impact of of concrete masonry unit (CMU). They are often walls for compliance with the building code. The space reinforcement as shown on the design drawings missiles, it should not be built of wood framing alone. unreinforcedcommercial and therefore building provide without little using resistance the floor to systembelow of thethe floor structure is designed itself. Into thisallow option, air to theflow safe through the stresses caused by extreme winds. provided with this publication, these walls cannot be Instead, it should be built of concrete or concrete room has a separate concrete slab floor installedso thaton top the offloor earth framing fill and will mustnot becomebe supported too damp. by It is important that the installation of the safe room not used as safe room walls since they are not reinforced masonry. Access to this type of safe room can be Buildingsteel a safe reinforced room inside concrete a home or on CMU a crawlspace foundation walls. The floor system may be designed as open block this air flow. to resist damage from missiles and uplift from provided through an existing window or door in an foundationand elevated,is more difficult but that than design building option a shelter is difficult to develop a prescriptive solution for and therefore extreme winds. exterior wall of the home. inside ais home not provided on a basement in this or publication. slab-on-grade An alternativeIn approach, general, it which is much may easier be moreto build economical, a safe room is inside to foundation. The main reason is that the entire safe • Exterior basement walls that are used as safe room In general, it is easier to add a safe room during the a new crawlspace home than in an existing crawlspace room, includingbuild an exterior its floor, safe must room be separate on a slab-on-grade from foundation adjacent to an outside wall of the home walls must not contain windows, doors, or other construction of a new slab-on-grade home than to home. If you plan to add a safe room to an existing the framingand provide of the home access or the through entire a floor door system installed in that wall. openings in the area providing protection. retrofit an existing slab-on-grade home. If you plan crawlspace home as a retrofitting project, keep the and foundation of the home will be required to be to add a safe room to a slab-on-grade home as a following points in mind: • The safe room must be built with its own ceiling, so constructedTaking to shel supportTer from the The extreme-wind sTorm: BUILDING loads A SAFE acting ROOM FOR YOUR HOME OR SMALL BUSINESS retrofitting project, keep the following points in mind: 21 that the occupants will be protected from missiles on the safe room. In Figure II-4, a safe room is built • The safe room must have a separate foundation. and falling debris. • The walls of the safe room must be completely inside the home or commercial building without Building the foundation inside the home would

74 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 75 seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon

Ventilation in the area below the floor of the home is also an important issue. The wood-framed floor of a home on a crawlspace foundation is typically held 18 to 30 inches above the ground by the foundation walls for compliance with the building code. The space below the floor is designed to allow air to flow through so that the floor framing will not become too damp. It is important that the installation of the safe room not block this air flow.

n The safe room must have a separate foundation. Building the foundation inside the home would require cutting out a section of the existing floor and installing new foundation members, fill dirt, and a new slab – a complicated and expensive operation that is often not practical. n A more practical and more economical approach would be to build an exterior safe room, made of concrete or concrete masonry, on a slab-on-grade foundation adjacent to an outside wall of the home, as described above.

requireFigure cutting II-4. out a section Figure II-4. of the existing floor and Cross-section: typical crawlspace warning (continued) Cross-section: typical crawlspace foundation, with installing new foundation foundation, with safe room safe room members, fill dirt, and a new 1. The Coastal High Hazard Area (VE zones) or other i.e., 2 feet above the flood elevation having a slab – a complicated and areas known to be subject to high-velocity wave 1 percent annual chance of being equaled or expensive operation that is action; or exceeded in any given year (100-year event); or often not practical. 2. Areas seaward of the Limit of Moderate Wave 3. The stillwater flood elevation associated with the • A more practical and more Action (LiMWA) where mapped, also referred to as 0.2 percent annual chance of being equaled or economical approach would the Coastal A Zone in ASCE 24-05; or exceeded in any given year (500-year event). be to build an exterior safe 3. Floodways; or Residential Tornado Safe Room Exception: Where room, made of concrete a residential tornado safe room is located outside of 4. Areas subject to coastal storm surge inundation or concrete masonry, on a the hurricane-prone region as identified on Figure associated with a Category 5 hurricane (where slab-on-grade foundation 3-2 of FEMA 361, and the community participates in applicable, these areas should be mapped areas adjacent to an outside wall the NFIP, the safe room need only be elevated to the studied by the U.S. Army Corps of Engineers of the home, as described minimum lowest floor elevation identified by the (USACE), NOAA, or other qualified sources). above. floodplain ordinance of the community. If it is not possible to install or place a residential Note, when installing a residential safe room in an safe room outside the SFHA, the residential safe area that has not been mapped or studied as part room may be placed in an area that has been of a NFIP flood study (or equivalent flood study), determined by detailed study to be in an A, shaded the top of the safe room floor should be elevated X, or unshaded X Zone, but still outside of the high such that it is 2 feet above the flood elevation hazard areas identified above. In the instances when corresponding to the highest recorded flood a residential safe room is needed in these flood- elevation in the area that has not been evaluated. prone areas, the top of the elevated floor of the Should no historical flood elevation data be safe room should be elevated to the highest of the available for the area, the elevation of the safe room elevations specified below (see the appropriate Flood floor should be set at the elevation identified by the Insurance Study (FIS) or Flood Insurance Rate Map local authority having jurisdiction. (FIRM)): In areas where Category 5 storm surges are not 1. The minimum elevation of the lowest floor mapped, references in this publication to “Category required by the floodplain ordinance of the 5” storm surge inundation areas should be taken to community (if such ordinance exists); or mean the area inundated by the highest storm surge Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS warning22 2. Two feet above the base flood elevation (BFE); category mapped. It is also important to remember that FEMA does area subject to storm surge inundation. Although not support placing safe rooms offering protection occupying such a safe room during a tornado may against extreme-wind events where floodwaters have be acceptable, provided that the safe room is located It is relatively easy and cost-effective to add a safe room the potential to endanger occupants within the safe where it will not be flooded by rains associated New vs. Existing Homes or Buildings when first building your home or small business. For room. Although the ICC-500 allows the placement with other storm and tornado events, it should The safe room designs in this publication were example, when the home is constructed with exterior of residential shelters in areas subject to flooding, not be used during a hurricane. A residential safe developed primarily for use in new homes or buildings, walls made from CMUs (also commonly known as FEMA safe room design criteria for residential safe room sited in the SFHA should meet the flood- but some can be used in existing buildings. When a “concrete block;” see Figure II-5), the near-absolute rooms significantly limit the placement of safe specific FEMA safe room design criteria listed below. new home is being built, the builder/contractor can protection level in FEMA 320 can be achieved by rooms in Special Flood Hazard Areas (SFHAs). A Consult your local building official or local National construct walls, foundations, and other parts of the slightly modifying the exterior walls at the safe room residential safe room may only be sited in mapped Flood Insurance Program (NFIP) representative to home as required to accommodate the safe room. space with additional steel reinforcement and grout. SFHA where no wave action or high-velocity water determine whether your home or small business, or Modifying the walls or foundation of an existing home The safe room is easily completed by adding interior flow is anticipated. Therefore, the installation of a a proposed stand-alone safe room site, is susceptible as necessary for the construction of a safe room is more walls constructed of reinforced CMU, a concrete roof safe room in a home supported by piles, piers, or to coastal or riverine flooding. In any case, the difficult. As a result, some of the safe room designs in deck over the safe room, and a special safe room door, columns should be scrutinized for its location with installation of any safe room in a hurricane-prone this publication are not practical for existing homes. as shown in Figure II-6. respect to flood hazards. With building connectors area should be coordinated with local emergency Constructing a safe room within your home or small commercially available, it is extremely difficult to management and law enforcement to ensure that its business puts it as close as possible to your family and/ Building a safe room in an existing home will typically economically and structurally separate the safe room use during extreme-wind events is not a violation of or employees. A safe room may be installed during the cost 20 percent more than building the same safe room from the elevated floor framing and ensure that any local or state evacuation plan. initial construction of a home or retrofitted afterward. in a new home under construction. Because the safe the safe room will withstand the forces of extreme room is being used for life safety and your home might Certain safe room designs provided in this As long as the design and construction requirements winds. be exposed to wind loads and debris impacts it was not publication may be elevated several feet above and guidance are followed, the same level of near- designed to resist, an architect or engineer (A/E) should If your safe room is located where coastal or riverine existing grade (see drawing sheets for specific absolute protection is provided by either type of safe be consulted to address special structural requirements flooding may occur during hurricanes, it should details). However, even though the safe room floor room. The following sections discuss these issues (even when using an A/E in such a project is not not be occupied during a hurricane. Further, a may be elevated, it should be located outside of the further. Also, for this discussion, the term “retrofit” required by the local building department). residential safe room should not be located in an following high-risk flood hazard areas: refers to the process of making changes to an existing building.

76 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 77 seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon

In general, it is much easier to build a safe room inside a new crawlspace home than in an existing crawlspace home. If you plan to add a safe room to an existing crawlspace home as a retrofitting project, keep the following points in mind: n The safe room must have a separate foundation. Building the foundation inside the home would require cutting out a section of the existing floor and installing new foundation members, fill dirt, and a new slab – a complicated and expensive operation that is often not practical. n A more practical and more economical approach would be to build an exterior safe room, made of concrete or concrete masonry, on a slab-on-grade foundation adjacent to an outside wall of the home, as described above. requireFigure cutting II-4. out a section Figure II-4. of the existing floor and Cross-section: typical crawlspace warning (continued) Cross-section: typical crawlspace foundation, with installing new foundation foundation, with safe room safe room members, fill dirt, and a new 1. The Coastal High Hazard Area (VE zones) or other i.e., 2 feet above the flood elevation having a slab – a complicated and areas known to be subject to high-velocity wave 1 percent annual chance of being equaled or expensive operation that is action; or exceeded in any given year (100-year event); or often not practical. 2. Areas seaward of the Limit of Moderate Wave 3. The stillwater flood elevation associated with the • A more practical and more Action (LiMWA) where mapped, also referred to as 0.2 percent annual chance of being equaled or economical approach would the Coastal A Zone in ASCE 24-05; or exceeded in any given year (500-year event). be to build an exterior safe 3. Floodways; or Residential Tornado Safe Room Exception: Where room, made of concrete a residential tornado safe room is located outside of 4. Areas subject to coastal storm surge inundation or concrete masonry, on a the hurricane-prone region as identified on Figure associated with a Category 5 hurricane (where slab-on-grade foundation 3-2 of FEMA 361, and the community participates in applicable, these areas should be mapped areas adjacent to an outside wall the NFIP, the safe room need only be elevated to the studied by the U.S. Army Corps of Engineers of the home, as described minimum lowest floor elevation identified by the (USACE), NOAA, or other qualified sources). above. floodplain ordinance of the community. If it is not possible to install or place a residential Note, when installing a residential safe room in an safe room outside the SFHA, the residential safe area that has not been mapped or studied as part room may be placed in an area that has been of a NFIP flood study (or equivalent flood study), determined by detailed study to be in an A, shaded the top of the safe room floor should be elevated X, or unshaded X Zone, but still outside of the high such that it is 2 feet above the flood elevation hazard areas identified above. In the instances when corresponding to the highest recorded flood a residential safe room is needed in these flood- elevation in the area that has not been evaluated. prone areas, the top of the elevated floor of the Should no historical flood elevation data be safe room should be elevated to the highest of the available for the area, the elevation of the safe room elevations specified below (see the appropriate Flood floor should be set at the elevation identified by the Insurance Study (FIS) or Flood Insurance Rate Map local authority having jurisdiction. (FIRM)): In areas where Category 5 storm surges are not 1. The minimum elevation of the lowest floor mapped, references in this publication to “Category required by the floodplain ordinance of the 5” storm surge inundation areas should be taken to community (if such ordinance exists); or mean the area inundated by the highest storm surge Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS warning22 2. Two feet above the base flood elevation (BFE); category mapped. It is also important to remember that FEMA does area subject to storm surge inundation. Although not support placing safe rooms offering protection occupying such a safe room during a tornado may against extreme-wind events where floodwaters have be acceptable, provided that the safe room is located It is relatively easy and cost-effective to add a safe room the potential to endanger occupants within the safe where it will not be flooded by rains associated New vs. Existing Homes or Buildings when first building your home or small business. For room. Although the ICC-500 allows the placement with other storm and tornado events, it should The safe room designs in this publication were example, when the home is constructed with exterior of residential shelters in areas subject to flooding, not be used during a hurricane. A residential safe developed primarily for use in new homes or buildings, walls made from CMUs (also commonly known as FEMA safe room design criteria for residential safe room sited in the SFHA should meet the flood- but some can be used in existing buildings. When a “concrete block;” see Figure II-5), the near-absolute rooms significantly limit the placement of safe specific FEMA safe room design criteria listed below. new home is being built, the builder/contractor can protection level in FEMA 320 can be achieved by rooms in Special Flood Hazard Areas (SFHAs). A Consult your local building official or local National construct walls, foundations, and other parts of the slightly modifying the exterior walls at the safe room residential safe room may only be sited in mapped Flood Insurance Program (NFIP) representative to home as required to accommodate the safe room. space with additional steel reinforcement and grout. SFHA where no wave action or high-velocity water determine whether your home or small business, or Modifying the walls or foundation of an existing home The safe room is easily completed by adding interior flow is anticipated. Therefore, the installation of a a proposed stand-alone safe room site, is susceptible as necessary for the construction of a safe room is more walls constructed of reinforced CMU, a concrete roof safe room in a home supported by piles, piers, or to coastal or riverine flooding. In any case, the difficult. As a result, some of the safe room designs in deck over the safe room, and a special safe room door, columns should be scrutinized for its location with installation of any safe room in a hurricane-prone this publication are not practical for existing homes. as shown in Figure II-6. respect to flood hazards. With building connectors area should be coordinated with local emergency Constructing a safe room within your home or small commercially available, it is extremely difficult to management and law enforcement to ensure that its business puts it as close as possible to your family and/ Building a safe room in an existing home will typically economically and structurally separate the safe room use during extreme-wind events is not a violation of or employees. A safe room may be installed during the cost 20 percent more than building the same safe room from the elevated floor framing and ensure that any local or state evacuation plan. initial construction of a home or retrofitted afterward. in a new home under construction. Because the safe the safe room will withstand the forces of extreme room is being used for life safety and your home might Certain safe room designs provided in this As long as the design and construction requirements winds. be exposed to wind loads and debris impacts it was not publication may be elevated several feet above and guidance are followed, the same level of near- designed to resist, an architect or engineer (A/E) should If your safe room is located where coastal or riverine existing grade (see drawing sheets for specific absolute protection is provided by either type of safe be consulted to address special structural requirements flooding may occur during hurricanes, it should details). However, even though the safe room floor room. The following sections discuss these issues (even when using an A/E in such a project is not not be occupied during a hurricane. Further, a may be elevated, it should be located outside of the further. Also, for this discussion, the term “retrofit” required by the local building department). residential safe room should not be located in an following high-risk flood hazard areas: refers to the process of making changes to an existing building.

76 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 77 seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon new vs. existing homes or Buildings Building a safe room in an existing home will typically cost 20 percent more than building the same The safe room designs in this publication were developed primarily for use in new homes or safe room in a new home under construction. Because the safe room is being used for life safety buildings, but some can be used in existing buildings. When a new home is being built, the and your home might be exposed to wind loads and debris impacts it was not designed to resist, builder/contractor can construct walls, foundations, and other parts of the home as required to an architect or engineer (A/E) should be consulted to address special structural requirements accommodate the safe room. Modifying the walls or foundation of an existing home as necessary (even when using an A/E in such a project is not required by the local building department). for the construction of a safe room is more difficult. As a result, some of the safe room designs in this publication are not practical for existing homes. Constructing a safe room within your home or small business puts it as close as possible to your family and/or employees. A safe room may be installed during the initial construction of a home or retrofitted afterward. As long as the safe room location design and construction requirements and guidance are followed, the same level of near-absolute There are several possible locations protection is provided by either type of safe room. The following sections discuss these issues further. Also, for this discussion, the term “retrofit” refers to the process of making changes to an in your home or small business existing building. for a safe room. Perhaps the most convenient and safest is below It is relatively easy and cost-effective to add a safe room when first building your home or small ground level in your basement. If business. For example, when the home is constructed with exterior walls made from CMUs seCTion ii: PLANNING YOUR SAFE ROOM your home or small business does ThIrd EdITIon (also commonly known as “concrete block;” see Figure II-5), the near-absolute protection level in not have a basement, you can install FEMA 320 can be achieved by slightly modifying the exterior walls at the safe room space with additional steel reinforcement and grout. The safe room is easily completed by adding interior Building a safe room in an existing home will typicallyan cost in-ground 20 percent safe moreroom thanbeneath building a the samesurviving interior rooms walls constructed of reinforced CMU, a concrete roof deck over the safe room, and a special safe safe room in a new home under construction. Becauseconcrete the safe slab-on-grade room is being foundation used for life safety room door, as shown in Figure II-6. and your home might be exposed to wind loads and ordebris a concrete impacts garage it was floor. not designed Although to resist, an architect or engineer (A/E) should be consulted tobasement address specialand in-ground structural safe requirements (even when using an A/E in such a project is not requiredrooms by provide the local the building highest department).level of protection against missiles and falling debris because they may be shielded from direct forces of wind and debris, the above-ground designs provided in this publication are also capable of providing near-absolute protection. This is an Safe Roomsafe Location room location important alternative to be aware of if you are not able to install a safe room in your basement due to There are several possible locations There are several possible locations in your concerns related to flood hazards or naturally-high groundwater tables at your site. home orin small your business home or for small a safe business room. Figure II-5. CMUs Perhaps the most convenient and safest is were used for the for a safe room. Perhaps the most below ground level in your basement. If Another alternative location for your safe room is an interior room on the first floor of the home exterior walls at convenient and safest is below your home or small business does not have or small business. Researchers, emergency response personnel, and people cleaning up after this home under seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon a basement,ground you levelcan install in your an basement. in-ground If construction (New tornadoes have often found an interior room of a home or small business still standing when safe roomyour beneath home a orconcrete small businessslab-on- does Smyrna Beach, all other above-ground parts of the home or small business have been destroyed. Closets, grade foundationseparatednot have orafrom basement,a concrete the structure garageyou can offloor. theinstall home or small business. This is to ensure the structural Florida). bathrooms, and small storage rooms offer the advantage of having a function other than providing Althoughintegrityan basement in-ground of the and safe safe in-ground room room, beneath shouldsafe rooms athe rest of thesurviving structure interior fail or rbeooms compromised during an seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon provide the highest level of protection against occasional storm protection. Typically, these rooms have only one door and no windows, which extreme-windconcrete slab-on-grade event. foundation missiles and falling debris because they may makes them well-suited for conversion to a safe room. Bathrooms have the added advantage of or a concrete garage floor. Although be shielded from direct forces of wind and including a water supply and toilet. debris, Figuresthebasement above-ground II-7 andthrough in-ground designs II-9 areprovided safe typical in floor plans on which possible locations for safe rooms are this publicationshownrooms with provide are yellowalso thecapable highlighting. highest of providing level These are not floor plans developed specifically for homes with Regardless of where in your home or small business near-absolutesafeof protection rooms; protection. they against showThis missilesis how an important safe and rooms can be added without changes to the layout of rooms. Figure II-5. CMUs were used for the exterior walls at this home under construction alternative to be aware of if you are not able to install a you build your safe room, the walls and ceiling of falling debris because they may be shielded from direct forces of wind and debris, the above-ground (New Smyrna Beach, Florida). safe room in your basement due to concerns related to the safe room must be built so that they will provide designs provided in this publication are also capable of providing near-absolute protection. This is an flood fhazardsloor Plan or naturally-high 1: basement groundwater tables at near-absolute protection for you, your family, or Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 25 your site.important alternative to be aware of if you are not able to install a safe room in your basement due to Possible safe room locations in a basement include the following: employees from missiles and falling debris, and concerns related to flood hazards or naturally-high groundwater tables at your site. Another alternative location for your safe room is an remain standing if your home or small business is interior roomn onIn thea corner first floorof the of basement, the home orpreferably small where the basement walls are below ground level severely damaged by extreme winds. If sections business.Another Researchers, alternative emergency location response for your personnel, safe room is an interior room on the first floor of the home n In a bathroom, closet, or other interior room in thes basementurviving interior room of your home’s or small business’ walls are used and peopleor small cleaning business. up after Researchers, tornadoes have emergency often response personnel, and people cleaning up after found an interior room of a home or small business as safe room walls, those wall sections must be still standingtornadoesn whenIn a haveallfreestanding other often above-ground found addition an interior partsto the of roombasement of a home or small business still standing when rest of the structure fail or be compromised during an the homeall or other small above-ground business have partsbeen destroyed. of the home or small business have been destroyed. Closets, A space that is to be used for a safe room must extreme-windbe keptTaking free shel ofevent.T erclutter from Tsohe thatsTorm: the BUILDING safe room A SAFE can ROOM FOR YOUR HOME OR SMALL BUSINESS 27 Closets, bathrooms,bathrooms, andand small small storage storage rooms rooms offer offer the the advantage of having a function other than providing Figure II-6. View be quickly and easily entered and so that the safe room occupants will not be injured by falling advantageoccasional of having storma function protection. other than Typically, providing these roomsFigures have II-7 onlythrough one II-9door are and typical no windows, floor plans which on of an in-home occasionalobjects. storm For protection. this reason, Typically, a bathroom these rooms is often a betterwhich choice possible for locations a safe room for safe than rooms a closet are shown or other makes them well-suited for conversion to a safe room. Bathrooms have the added advantage of safe room under have onlyspace one useddoor andfor storage. no windows, Remember, which makes if the basementwith yellowis below highlighting. the level of These storm are surge not floor or the plans level construction. The including a water supply and toilet. them well-suitedof flooding for from conversion any other to a source,safe room. it is not a suitabledeveloped location specifically for a safe for room.homes In withthis safe situation, rooms; theya CMU walls of Bathrooms have the added advantage of including a show how safe rooms can be added without changes to possible alternative would be to build an exterior safe room, adjacent to your home, on a slab-on- this safe room are water supply and toilet. Regardlessthe layout of of rooms. where in your home or small business fully grouted and grade above the flood level. are reinforced, Regardless of where in your home or small business you build your safe room, the walls and ceiling of vertically, with you build your safe the safe room must be built so that they will provide steel reinforcing room, the walls and near-absolute protection for you, your family, or ceiling Figureof the II-7.safe room bars from the Figure II-7. must beFloor built plan so that1: basement employees from missiles and falling debris, and foundation to the Floor plan 1: basement concrete roof deck they will provide near- remain standing if your home or small business is (New Smyrna absolute protection for severely damaged by extreme winds. If sections Beach, Florida). you, your family,surviving or interior room of your home’s or small business’ walls are used employees from missiles as safe room walls, those wall sections must be and falling debris, and remain standing if your home orTaking small shel businessTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 27 is severely damaged by extreme winds. If sections of your home’s or small business’ walls are used as safe room walls, those wall sections must be separated from the structure of the home or small business. This is to ensure the structural integrity of the Possible safe room location safe room, should the

78 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 79 Figure II-6. View of an in-home safe room under construction. The CMU walls of this safe room are fully grouted and are reinforced, vertically, with steel reinforcing bars from the foundation to the concrete roof deck (New Smyrna Beach, Florida). 28 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 26 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon new vs. existing homes or Buildings Building a safe room in an existing home will typically cost 20 percent more than building the same The safe room designs in this publication were developed primarily for use in new homes or safe room in a new home under construction. Because the safe room is being used for life safety buildings, but some can be used in existing buildings. When a new home is being built, the and your home might be exposed to wind loads and debris impacts it was not designed to resist, builder/contractor can construct walls, foundations, and other parts of the home as required to an architect or engineer (A/E) should be consulted to address special structural requirements accommodate the safe room. Modifying the walls or foundation of an existing home as necessary (even when using an A/E in such a project is not required by the local building department). for the construction of a safe room is more difficult. As a result, some of the safe room designs in this publication are not practical for existing homes. Constructing a safe room within your home or small business puts it as close as possible to your family and/or employees. A safe room may be installed during the initial construction of a home or retrofitted afterward. As long as the safe room location design and construction requirements and guidance are followed, the same level of near-absolute There are several possible locations protection is provided by either type of safe room. The following sections discuss these issues further. Also, for this discussion, the term “retrofit” refers to the process of making changes to an in your home or small business existing building. for a safe room. Perhaps the most convenient and safest is below It is relatively easy and cost-effective to add a safe room when first building your home or small ground level in your basement. If business. For example, when the home is constructed with exterior walls made from CMUs seCTion ii: PLANNING YOUR SAFE ROOM your home or small business does ThIrd EdITIon (also commonly known as “concrete block;” see Figure II-5), the near-absolute protection level in not have a basement, you can install FEMA 320 can be achieved by slightly modifying the exterior walls at the safe room space with additional steel reinforcement and grout. The safe room is easily completed by adding interior Building a safe room in an existing home will typicallyan cost in-ground 20 percent safe moreroom thanbeneath building a the samesurviving interior rooms walls constructed of reinforced CMU, a concrete roof deck over the safe room, and a special safe safe room in a new home under construction. Becauseconcrete the safe slab-on-grade room is being foundation used for life safety room door, as shown in Figure II-6. and your home might be exposed to wind loads and ordebris a concrete impacts garage it was floor. not designed Although to resist, an architect or engineer (A/E) should be consulted tobasement address specialand in-ground structural safe requirements (even when using an A/E in such a project is not requiredrooms by provide the local the building highest department).level of protection against missiles and falling debris because they may be shielded from direct forces of wind and debris, the above-ground designs provided in this publication are also capable of providing near-absolute protection. This is an Safe Roomsafe Location room location important alternative to be aware of if you are not able to install a safe room in your basement due to There are several possible locations There are several possible locations in your concerns related to flood hazards or naturally-high groundwater tables at your site. home orin small your business home or for small a safe business room. Figure II-5. CMUs Perhaps the most convenient and safest is were used for the for a safe room. Perhaps the most below ground level in your basement. If Another alternative location for your safe room is an interior room on the first floor of the home exterior walls at convenient and safest is below your home or small business does not have or small business. Researchers, emergency response personnel, and people cleaning up after this home under seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon a basement,ground you levelcan install in your an basement. in-ground If construction (New tornadoes have often found an interior room of a home or small business still standing when safe roomyour beneath home a orconcrete small businessslab-on- does Smyrna Beach, all other above-ground parts of the home or small business have been destroyed. Closets, grade foundationseparatednot have orafrom basement,a concrete the structure garageyou can offloor. theinstall home or small business. This is to ensure the structural Florida). bathrooms, and small storage rooms offer the advantage of having a function other than providing Althoughintegrityan basement in-ground of the and safe safe in-ground room room, beneath shouldsafe rooms athe rest of thesurviving structure interior fail or rbeooms compromised during an seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon provide the highest level of protection against occasional storm protection. Typically, these rooms have only one door and no windows, which extreme-windconcrete slab-on-grade event. foundation missiles and falling debris because they may makes them well-suited for conversion to a safe room. Bathrooms have the added advantage of or a concrete garage floor. Although be shielded from direct forces of wind and including a water supply and toilet. debris, Figuresthebasement above-ground II-7 andthrough in-ground designs II-9 areprovided safe typical in floor plans on which possible locations for safe rooms are this publicationshownrooms with provide are yellowalso thecapable highlighting. highest of providing level These are not floor plans developed specifically for homes with Regardless of where in your home or small business near-absolutesafeof protection rooms; protection. they against showThis missilesis how an important safe and rooms can be added without changes to the layout of rooms. Figure II-5. CMUs were used for the exterior walls at this home under construction alternative to be aware of if you are not able to install a you build your safe room, the walls and ceiling of falling debris because they may be shielded from direct forces of wind and debris, the above-ground (New Smyrna Beach, Florida). safe room in your basement due to concerns related to the safe room must be built so that they will provide designs provided in this publication are also capable of providing near-absolute protection. This is an flood fhazardsloor Plan or naturally-high 1: basement groundwater tables at near-absolute protection for you, your family, or Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 25 your site.important alternative to be aware of if you are not able to install a safe room in your basement due to Possible safe room locations in a basement include the following: employees from missiles and falling debris, and concerns related to flood hazards or naturally-high groundwater tables at your site. Another alternative location for your safe room is an remain standing if your home or small business is interior roomn onIn thea corner first floorof the of basement, the home orpreferably small where the basement walls are below ground level severely damaged by extreme winds. If sections business.Another Researchers, alternative emergency location response for your personnel, safe room is an interior room on the first floor of the home n In a bathroom, closet, or other interior room in thes basementurviving interior room of your home’s or small business’ walls are used and peopleor small cleaning business. up after Researchers, tornadoes have emergency often response personnel, and people cleaning up after found an interior room of a home or small business as safe room walls, those wall sections must be still standingtornadoesn whenIn a haveallfreestanding other often above-ground found addition an interior partsto the of roombasement of a home or small business still standing when rest of the structure fail or be compromised during an the homeall or other small above-ground business have partsbeen destroyed. of the home or small business have been destroyed. Closets, A space that is to be used for a safe room must extreme-windbe keptTaking free shel ofevent.T erclutter from Tsohe thatsTorm: the BUILDING safe room A SAFE can ROOM FOR YOUR HOME OR SMALL BUSINESS 27 Closets, bathrooms,bathrooms, andand small small storage storage rooms rooms offer offer the the advantage of having a function other than providing Figure II-6. View be quickly and easily entered and so that the safe room occupants will not be injured by falling advantageoccasional of having storma function protection. other than Typically, providing these roomsFigures have II-7 onlythrough one II-9door are and typical no windows, floor plans which on of an in-home occasionalobjects. storm For protection. this reason, Typically, a bathroom these rooms is often a betterwhich choice possible for locations a safe room for safe than rooms a closet are shown or other makes them well-suited for conversion to a safe room. Bathrooms have the added advantage of safe room under have onlyspace one useddoor andfor storage. no windows, Remember, which makes if the basementwith yellowis below highlighting. the level of These storm are surge not floor or the plans level construction. The including a water supply and toilet. them well-suitedof flooding for from conversion any other to a source,safe room. it is not a suitabledeveloped location specifically for a safe for room.homes In withthis safe situation, rooms; theya CMU walls of Bathrooms have the added advantage of including a show how safe rooms can be added without changes to possible alternative would be to build an exterior safe room, adjacent to your home, on a slab-on- this safe room are water supply and toilet. Regardlessthe layout of of rooms. where in your home or small business fully grouted and grade above the flood level. are reinforced, Regardless of where in your home or small business you build your safe room, the walls and ceiling of vertically, with you build your safe the safe room must be built so that they will provide steel reinforcing room, the walls and near-absolute protection for you, your family, or ceiling Figureof the II-7.safe room bars from the Figure II-7. must beFloor built plan so that1: basement employees from missiles and falling debris, and foundation to the Floor plan 1: basement concrete roof deck they will provide near- remain standing if your home or small business is (New Smyrna absolute protection for severely damaged by extreme winds. If sections Beach, Florida). you, your family,surviving or interior room of your home’s or small business’ walls are used employees from missiles as safe room walls, those wall sections must be and falling debris, and remain standing if your home orTaking small shel businessTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 27 is severely damaged by extreme winds. If sections of your home’s or small business’ walls are used as safe room walls, those wall sections must be separated from the structure of the home or small business. This is to ensure the structural integrity of the Possible safe room location safe room, should the

floor Plan 3: below-grade safe rooms Possible locations for an in-ground safe room include the following: n Below the slab in a closet or storage room Floor Plan 1: basement Regardless of where the safe room is built, it must be Floor Plan 3: below-grade safe rooms Because of the difficulty of installing an in-ground safe equipped with a door that will resist the impact of n Below the floor of the garage, in an area whereroom incars an existingwill not behome, parked this type of safe room is Possible safe room locations in a basement include the Possible locations for an in-ground safe room include windborne debris (missiles). Remember, if ThtheIrd first EdITI on practical only for new construction. Remember, if the following: seCTion ii: PLANNING YOUR SAFE ROOM ThtheIrd following: EdITIon seCTion ii: floor PLANNING of the YOUR home SAFE or small ROOM business is in an area that is Because of the difficulty of installing an in-ground safefirst roomfloor inof anthe existing home is home,in an area this subjecttype of to safe storm • In a corner of the basement, preferably where the susceptible to storm surge from a Category 5 hurricane, • Below the slab in a closet or storage room surge or below the level of flooding from any other basementfloor walls Plan are 2: below safe roomsground onlevel the primary level itof is a not home a suitable or small location business for a residential safe room. room is practical only for new construction. Remember,source, if itthe is notfirst a floorsuitable of locationthe home for is a insafe an room. area In floor Plan 2: safe rooms on the primary level of a home or small business • Below the floor of the garage, in an area where cars Also, installation of safe rooms in SFHAs should only subject to storm surge or below the level of floodingthis from situation, any other see the source, previous it is section not a forsuitable guidance on • In a bathroom,Possible safecloset, room or other locations interior in rooma home in theon a slab-on-grade or crawlspace foundation include the will not be parked Possible safe room locationsoccur if thein a flood home design on a slab-on-gradecriteria for FEMA or safe crawlspace rooms foundation includelocation the for a safe room. In this situation, see the previousa possible section alternative for guidance to build an on exterior a possible safe room on basementfollowing spaces on the first floor: following spaces on theare firstmet andfloor: approval has been provided by local alternative to build an exterior safe room on a slab-on-gradea slab-on-grade elevated elevated on fillon fillabove above the the flood flood level. level. • In a freestandingn Bathroom addition to the basement jurisdictional authorities responsible for evacuating n Bathroom the area in the event of a hurricane and ensuring A space that is to be used for a safe room must be kept NFIP compliance. The prescriptive designs presented n Closet n free of clutter so that the safe room can be quicklyCloset and in this publication can only be elevated a few feet easily enteredn and so that the safe room occupants Storage room n Storage roomabove existing grade and, therefore, may not comply will not be injured by falling objects. For this reason, a with flood design criteria for residential safe rooms, bathroom isn often laundry a better room choice (provided for a safe the room load-bearing than which wall meansbetween the itsafe and room the garage,designs presented as shown in in this a closet or other space used for storage. nRemember, laundry room (provided the load-bearing wall between it and the garage, as shown in Figure II-8, can be properlyFigure separated II-8, can frompublication be the properly structure should separated of not the be home) installed.from the Instructure this situation, of the home) if the basement is below the level of storm surge or a possible alternative would be to build an exterior the level of nflooding from any other source, it is not Corner of the garage n Corner of the safegarage room on a slab-on-grade elevated on fill above the a suitable location for a safe room. In this situation, a flood level. possible alternative would be to build an exterior safe room, adjacentRegardless to your of wherehome, theon asafe Regardlessslab-on-grade room is ofbuilt, above where it must the besafe equipped room is withbuilt, a it door must that be equippedwill resist thewith a door that will resist the the floodimpact level. of windborne debrisimpact (missiles). of windborne Remember, debris if the (missiles). first floor Remember, of the home if the or firstsmall floor business of the home or small business is in an area that is susceptibleis in an to areastorm that surge is susceptible from a Category to storm 5 hurricane, surge from it ais Categorynot a suitable 5 hurricane, it is not a suitable Floor Planlocation 2: safe for rooms a residential on the primary safe room. level ofAlso, a installation of safe rooms in SFHAs should only occur home or small businesslocation for a residential safe room. Also, installation of safe rooms in SFHAs should only occur if the flood design criteria iffor the FEMA flood safedesign rooms criteria are formet FEMAand approval safe rooms has arebeen met provided and approval by has been provided by Possiblelocal safe roomjurisdictional locations authorities in a home responsibleon a slab-on- for evacuating the area in the event of a hurricane and grade or crawlspace foundation includelocal the jurisdictional following authorities responsible for evacuating the area in the event of a hurricane and ensuring NFIP compliance. The prescriptive designs presented in this publication can only be spaces on the first floor: ensuring NFIP compliance. The prescriptive designs presented in this publication can only be elevated a few feet above existing grade and, therefore, • Bathroom elevated a few feet above existing grade and, therefore, may not comply with floodmay design not complycriteria forwith residential flood design criteria for residential Entrance to possible • Closet safe rooms, which means safethe safe rooms, room which designs means presented the safe room designs presented safe room location • Storagein roomthis publication should not be installed. In this situation, in this publication should not be installed. In this situation, Figure II-9. Floor plan 3: in-ground (below-grade) safe rooms in a home on a slab-on-grade foundation • Laundrya possible room (provided alternative the a possible alternative load-bearingwould bewall to between build an it would be to build an Figure II-9. Floor plan 3: in-ground (below-grade) safe rooms in a home on a slab-on-grade and theexterior garage, safe as shown room inon a exterior safe room on a Figure II-8, can be properly Floorfoundation Plan 4: multi-purpose safe rooms slab-on-grade elevated slab-on-grade elevated separatedon fill from above the structurethe flood in a small business of the home) on fill above the flood level. Smallfloor businesses Plan 4: can multi-purpose use prescriptive safe safe roomsroom designs in a small Tables business II-1 and II-2 will help you decide what type • Corner of the garage level. for multi-purpose safe rooms (see Figure II-10). Using of safe room is appropriate for your circumstances. a 14-footSmall by businesses 14-foot safe can room, use the prescriptive area used for safe life- room designsTable II-1 for applies multi-purpose to the construction safe rooms of safe(see rooms in safetyFigure protection II-10). can Using also a be 14-foot adapted by for 14-foot a conference safe room, new the homesarea used or buildings. for life-safety Table protectionII-2 applies canto retrofit also roombe or adapted other purpose, for a conference provided the room equipment or other purpose,situations, provided in the which equipment a safe room and is fixtures being added placed to an and infixtures the safe placed room in canthe besafe removed room can quickly be removed and efficiently.existing When home placing or building. safe rooms in buildings quickly and efficiently. When placing safe rooms in buildingslarger larger than thantypical typical residential residential structures, structures, the layout should be designed so that the safe room the layoutis quickly should accessible be designed from so most that theareas safe on room the floor. If a larger safe room size is desired, design is quicklyguidance accessible in FEMA from 361 most can areas be onused. the floor. If a larger safe room size is desired, design guidance in FEMA 361 can be used. 30 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS

Possible safe room location Possible safe room location

Figure II-8. Floor plan 2: home on a slab-on-grade or Figure II-8. Figurecrawlspace II-8. foundation Floor plan 2: home on a slab-on-gradeFloor plan or 2:crawlspace home on afoundation slab-on-grade or crawlspace foundation

Possible safe room location Possible safe room location

80 | Taking shel ShelterTer from from T hethe s TStorm:orm: BUILDING Building A SAFE a Safe ROOM Room FOR YOUR HOME OR SMALL BUSINESS ARCHITECTURE29 ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 81 Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 29 Table II-1. Appropriate types of safe rooms for new homes and buildings seCTion ii: PLANNING YOUR SAFE ROOM ThIrd EdITIon Appropriate Safe Room Type Safe Room Considerations Basement In-Ground* Above-Ground (New Homes or Buildings) Possible safe room location House or building located in a storm surge area NA NA NA House or building located in a flood hazard area++ NA NA 4 High water table 4 Low cost 4 Long-term safe room occupancy comfort 4 4 Least likely to be hit or impacted by windborne debris 4 4

Table II-2. Appropriate types of safe rooms for existing homes and buildings Appropriate Safe Room Type Safe Room Considerations Basement In-Ground* Above-Ground (Existing Homes or Buildings) House or building located in a storm surge area NA NA NA House or building located in a flood hazard area++ NA NA 4 High water table 4 Low cost 4 Long-term safe room occupancy comfort 4 4 Least likely to be hit or impacted by windborne debris 4 4 Easy retrofit 4 Ease of separating safe room from structural framing of house or building 4 4 Minimal disruption to house or building 4 Ease of accessibility 4

NA = Not Appropriate

* The in-ground safe rooms referred to in this publication ++ Per flood design criteria for FEMA safe rooms (see pages 76 are built below ground inside a home or building and and 77), elevation of a safe room is only permitted when therefore can be entered directly from within the home specific flood design criteria have been met and when or building. Other types of in-ground safe rooms are approved by the jurisdictional authority responsible for available that are designed to be installed outside a home evacuations and NFIP compliance. or building. Entering one of these exterior in-ground safe rooms would require leaving the home or building. This publication does not contain any designs or other information about exterior in-ground safe rooms.

NA = Not Appropriate

Construction Materials other material for those specified in the designs. Figure II-10. Figure II-10. Floor Plan 4: multi-purpose safe rooms in a small business or public building One of the most vulnerable parts of your safe room is Floor Plan 4: multi-purpose safe rooms in a small business or public building The materials your builder/contractor will need to build your safe room should be available from building the door. The WISE Center at Texas Tech University Tables II-1 and II-2 will help you decide what type of safe room is appropriate for your material suppliers in your community. These materials tested the materials specified for doors in the safe room have been carefully selected for their strength, designs in this publication for their ability to carry circumstances. Table II-1 applies to the construction of safe rooms in new homes or buildings. durability, and/or ability to be readily combined in wind loads and prevent perforation by missiles. The Table II-2 applies to retrofit situations, in which a safe room is being added to an existing home ways that enable them to withstand the forces of installation of the door is as important as the materials or building. extreme winds and the impact of windborne missiles. used in its construction. Please confirm with your Your builder/ contractor should not substitute any builder/contractor that the door to your safe room can Taking shelTer from The sTorm: BUILDING A SAFE ROOM FOR YOUR HOME OR SMALL BUSINESS 82 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE 31 ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 83 be installed as shown in the design drawings included constructed as pre-manufactured units. These pre- for shelters that meet the FEMA 320 criteria in the Table II-3 shows the average costs for building two with this publication. A door specification has been manufactured units are constructed from a variety form of a quality verification process and seal program. types of safe rooms (above-ground [AG] and in-ground provided in the plans if you cannot obtain a door that of elements such as metal panels, fiberglass shells, Through independent testing and third party design [IG]) in new homes on basement, slab-on-grade, and meets the debris impact testing requirements for a Kevlar product systems, and many more. Others are reviews, participating members of the NSSA have crawlspace foundations according to the design plans 15-lb 2x4 board member traveling horizontally at 100 shelters that use common building materials or are received “seals” indicating that their shelters have in this publication. These costs are for safe rooms with mph (see ICC-500, Chapter 8 for the debris impact new innovations from the building industry such as been designed to meet the wind and debris impact a floor area of 8 feet by 8 feet and 14 feet by 14 feet. testing procedure to be used). structural insulated panels (SIPs). Because FEMA 320 protection criteria of FEMA 320. As a result, many The cost of retrofitting an existing home to add a was accepted as a “pre-standard” for the design and pre-manufactured shelters have been verified and A complete list of the safe room construction materials, safe room will vary with the size of the home and construction of shelters and safe rooms, many of these labeled with “seals” indicating that they comply with their expected strengths or properties, is included its construction type. In general, safe room costs for shelters have been designed to the FEMA criteria for with the FEMA 320 residential safe room design in the safe room designs provided in this publication. existing homes will be approximately 20 percent residential safe rooms; that is, they are capable of criteria. Therefore, when it can be verified that these Your builder/ contractor should use it when buying the higher than those shown in Table II-3. resisting 250 mph winds (3-second gust) and the debris pre-manufactured shelters are installed on a proper materials for your safe room. associated with such wind events (represented as a 15- foundation, and are elevated and sited to meet the It is also interesting to note that the cost differential There are other viable and appropriate shelters that lb 2x4 wood board traveling 100 mph). flood design criteria provided herein, these proprietary between constructing the combined tornado and have been designed and constructed to meet FEMA’s shelters can be viewed as an appropriate alternative to hurricane safe rooms presented in this publication It is important for prospective safe room owners to design criteria for residential safe rooms that are not the designs presented in this publication. and those that may be constructed to meet the ICC- know that FEMA does not certify, approve, or license included in this publication. Since the first edition 500 residential hurricane (only) safe room design the design and construction of shelters to be called safe FEMA supports the work of the NSSA to promote the of FEMA 320 was released in 1998, many tornado criteria is not a significant cost savings. Construction rooms. However, groups such as the National Storm design and construction of shelters that meet the near- events have occurred highlighting the importance of cost comparisons for some of the common building Shelter Association (NSSA) have stepped forward to absolute protection criteria set forth in this document. installing a safe room in homes or small businesses. materials used in the prescriptive designs of this help regulate the residential shelter industry. Since the The efforts of NSSA allow individual or proprietary Individuals and companies began designing shelters publication were performed. release of its Association Standard in April 2001 (NSSA designs to be included in the market place and to provide alternatives to the prescriptive solutions Standard for the Design, Construction, and Performance considered alongside the FEMA safe room designs as For the masonry and concrete safe rooms, wall and presented here. As a result, a residential tornado and of Storm Shelters), the NSSA has provided certifications options for homeowners and business owners looking roof sections that were identified through testing hurricane shelter industry has evolved. to provide protection from extreme-wind events that as capable of resisting a test missile that had similar Many of these shelter products are designed and Additional information regarding pre-manufactured may impact their homes or buildings. For additional impact momentum as the ICC-500 design missile were shelters is presented in the Consumer Guide in information on the NSSA and other shelter products selected. Because the ICC-500 is a new standard, very Structural Insulated Panels (SIPs) are a construction Section III of this publication. It is important to that meet the FEMA criteria, see the Consumer Guide few tests have been performed for missile-resistant innovation that is being used in some residential remember that, as with site-built safe rooms and provided in Section III. systems for the ICC-500 missile. Test results from construction. SIPs are composite building materials, shelters, pre-manufactured shelters should be Texas Tech University’s WISE Center, Florida A&M consisting of two layers of structural board with attached to an appropriate foundation. A structural University, Florida State University, and the University insulating foam in between. Some SIPs have been engineer should always be consulted to ensure that of Florida were used to identify wall sections that had designed such that they are capable of resisting the the prefabricated shelter is being installed on an Safe Room Cost been tested. For these types of safe rooms, the costs design wind and debris impact criteria of FEMA 320. appropriate and adequate foundation. to construct the ICC-500 residential hurricane safe When designed and constructed per the specifications room typically provided a cost savings of only 10 to on the design plans, these safe rooms meet or exceed 15 percent when compared to the cost to construct II-3. Average costs for both 8-foot by 8-foot and 14-foot by 14-foot safe rooms in new homes or buildings the design requirements for tornadoes and hurricanes the FEMA 320 safe rooms presented in Table II-3. Applicable Average as identified in the ICC-500 Storm Shelter Standard. Proprietary safe rooms were not included in this cost 1, 2, 3, 4 1, 3, 4 Size Safe Room Type Drawing No. Cost Pre-fabricated shelters are also available for installation comparison as no pre-manufactured shelters meeting Concrete Masonry Unit (CMU) Walls AG-01,02,03 $8,200 by a builder/contractor when first building your home, the new ICC-500 requirements were able to be Concrete Walls AG-01,02,03 $8,100 but are not explicitly addressed by this publication. identified. 8-foot x 8-foot The basic cost to design and construct a safe room Wood-Frame with CMU Infill AG-05 $7,600 These findings, however, were not surprising when x 8-foot during the construction of a new home starts at considering the common building materials used. As Safe Rooms Wood-Frame with Plywood/Steel Sheathing AG-06 $6,300 approximately $6,000, with larger, more refined, and Insulating Concrete Form AG-08,09 $8,300 more comfortable designs costing more than $15,000. was the case when the First Edition of FEMA 320 was prepared, the safe room design for these small safe Reinforced Concrete Box2 IG-01 $7,000 The cost of your safe room will vary according to the following: rooms is typically governed by the ability of the walls CMU Walls AG-01,02,03 $13,500 and doors to provide debris impact-resistance. When • The size of the safe room 14-foot x 14-foot Concrete Walls AG-01,02,03 $13,100 considering the factors that are involved (250 mph x 8-foot Wood-Frame with CMU Infill AG-05 $13,600 • The location of the safe room vs. 160 mph design wind speeds and debris impact- resistance for different weight and speed missiles), Safe Rooms Wood-Frame with Plywood/Steel Sheathing AG-06 $11,400 • The number of exterior home walls used in the the net savings is measurable but not large as the Insulating Concrete Form AG-08,09 $13,400 construction of the safe room reduction of materials from the design is typically 1 All safe room types shown in this table are above-ground are very dependent on site-specific soil conditions and the • The type of door used limited to a reduction in reinforcing steel, connectors, (AG) types for slab-on-grade foundations. Safe rooms building materials used. or wall thickness. For both the masonry and concrete constructed in basements or on crawlspaces will differ • The type of foundation on which your home is built safe rooms, there was still a basic wall thickness that 3 See drawings in this publication for specific materials used, slightly in price based on the foundations used. needed to be provided to resist both the debris impacts sizes, and other values needed for estimating purposes. • Your location within the United States (because of and the wind loads. 2 Below-ground safe room were estimated for a 5-foot by regional variations in labor and material costs) 5-foot by 8-foot (deep) safe room. The cost included a cast- 4 Costs provided are budgetary cost estimates calculated to in-place footing and safe room top, but the safe room walls 2008 U.S. dollar values. • Whether you are building a safe room into a new were a pre-cast unit. The costs for these types of safe rooms home or retrofitting an existing home

84 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 85 be installed as shown in the design drawings included constructed as pre-manufactured units. These pre- for shelters that meet the FEMA 320 criteria in the Table II-3 shows the average costs for building two with this publication. A door specification has been manufactured units are constructed from a variety form of a quality verification process and seal program. types of safe rooms (above-ground [AG] and in-ground provided in the plans if you cannot obtain a door that of elements such as metal panels, fiberglass shells, Through independent testing and third party design [IG]) in new homes on basement, slab-on-grade, and meets the debris impact testing requirements for a Kevlar product systems, and many more. Others are reviews, participating members of the NSSA have crawlspace foundations according to the design plans 15-lb 2x4 board member traveling horizontally at 100 shelters that use common building materials or are received “seals” indicating that their shelters have in this publication. These costs are for safe rooms with mph (see ICC-500, Chapter 8 for the debris impact new innovations from the building industry such as been designed to meet the wind and debris impact a floor area of 8 feet by 8 feet and 14 feet by 14 feet. testing procedure to be used). structural insulated panels (SIPs). Because FEMA 320 protection criteria of FEMA 320. As a result, many The cost of retrofitting an existing home to add a was accepted as a “pre-standard” for the design and pre-manufactured shelters have been verified and A complete list of the safe room construction materials, safe room will vary with the size of the home and construction of shelters and safe rooms, many of these labeled with “seals” indicating that they comply with their expected strengths or properties, is included its construction type. In general, safe room costs for shelters have been designed to the FEMA criteria for with the FEMA 320 residential safe room design in the safe room designs provided in this publication. existing homes will be approximately 20 percent residential safe rooms; that is, they are capable of criteria. Therefore, when it can be verified that these Your builder/ contractor should use it when buying the higher than those shown in Table II-3. resisting 250 mph winds (3-second gust) and the debris pre-manufactured shelters are installed on a proper materials for your safe room. associated with such wind events (represented as a 15- foundation, and are elevated and sited to meet the It is also interesting to note that the cost differential There are other viable and appropriate shelters that lb 2x4 wood board traveling 100 mph). flood design criteria provided herein, these proprietary between constructing the combined tornado and have been designed and constructed to meet FEMA’s shelters can be viewed as an appropriate alternative to hurricane safe rooms presented in this publication It is important for prospective safe room owners to design criteria for residential safe rooms that are not the designs presented in this publication. and those that may be constructed to meet the ICC- know that FEMA does not certify, approve, or license included in this publication. Since the first edition 500 residential hurricane (only) safe room design the design and construction of shelters to be called safe FEMA supports the work of the NSSA to promote the of FEMA 320 was released in 1998, many tornado criteria is not a significant cost savings. Construction rooms. However, groups such as the National Storm design and construction of shelters that meet the near- events have occurred highlighting the importance of cost comparisons for some of the common building Shelter Association (NSSA) have stepped forward to absolute protection criteria set forth in this document. installing a safe room in homes or small businesses. materials used in the prescriptive designs of this help regulate the residential shelter industry. Since the The efforts of NSSA allow individual or proprietary Individuals and companies began designing shelters publication were performed. release of its Association Standard in April 2001 (NSSA designs to be included in the market place and to provide alternatives to the prescriptive solutions Standard for the Design, Construction, and Performance considered alongside the FEMA safe room designs as For the masonry and concrete safe rooms, wall and presented here. As a result, a residential tornado and of Storm Shelters), the NSSA has provided certifications options for homeowners and business owners looking roof sections that were identified through testing hurricane shelter industry has evolved. to provide protection from extreme-wind events that as capable of resisting a test missile that had similar Many of these shelter products are designed and Additional information regarding pre-manufactured may impact their homes or buildings. For additional impact momentum as the ICC-500 design missile were shelters is presented in the Consumer Guide in information on the NSSA and other shelter products selected. Because the ICC-500 is a new standard, very Structural Insulated Panels (SIPs) are a construction Section III of this publication. It is important to that meet the FEMA criteria, see the Consumer Guide few tests have been performed for missile-resistant innovation that is being used in some residential remember that, as with site-built safe rooms and provided in Section III. systems for the ICC-500 missile. Test results from construction. SIPs are composite building materials, shelters, pre-manufactured shelters should be Texas Tech University’s WISE Center, Florida A&M consisting of two layers of structural board with attached to an appropriate foundation. A structural University, Florida State University, and the University insulating foam in between. Some SIPs have been engineer should always be consulted to ensure that of Florida were used to identify wall sections that had designed such that they are capable of resisting the the prefabricated shelter is being installed on an Safe Room Cost been tested. For these types of safe rooms, the costs design wind and debris impact criteria of FEMA 320. appropriate and adequate foundation. to construct the ICC-500 residential hurricane safe When designed and constructed per the specifications room typically provided a cost savings of only 10 to on the design plans, these safe rooms meet or exceed 15 percent when compared to the cost to construct II-3. Average costs for both 8-foot by 8-foot and 14-foot by 14-foot safe rooms in new homes or buildings the design requirements for tornadoes and hurricanes the FEMA 320 safe rooms presented in Table II-3. Applicable Average as identified in the ICC-500 Storm Shelter Standard. Proprietary safe rooms were not included in this cost 1, 2, 3, 4 1, 3, 4 Size Safe Room Type Drawing No. Cost Pre-fabricated shelters are also available for installation comparison as no pre-manufactured shelters meeting Concrete Masonry Unit (CMU) Walls AG-01,02,03 $8,200 by a builder/contractor when first building your home, the new ICC-500 requirements were able to be Concrete Walls AG-01,02,03 $8,100 but are not explicitly addressed by this publication. identified. 8-foot x 8-foot The basic cost to design and construct a safe room Wood-Frame with CMU Infill AG-05 $7,600 These findings, however, were not surprising when x 8-foot during the construction of a new home starts at considering the common building materials used. As Safe Rooms Wood-Frame with Plywood/Steel Sheathing AG-06 $6,300 approximately $6,000, with larger, more refined, and Insulating Concrete Form AG-08,09 $8,300 more comfortable designs costing more than $15,000. was the case when the First Edition of FEMA 320 was prepared, the safe room design for these small safe Reinforced Concrete Box2 IG-01 $7,000 The cost of your safe room will vary according to the following: rooms is typically governed by the ability of the walls CMU Walls AG-01,02,03 $13,500 and doors to provide debris impact-resistance. When • The size of the safe room 14-foot x 14-foot Concrete Walls AG-01,02,03 $13,100 considering the factors that are involved (250 mph x 8-foot Wood-Frame with CMU Infill AG-05 $13,600 • The location of the safe room vs. 160 mph design wind speeds and debris impact- resistance for different weight and speed missiles), Safe Rooms Wood-Frame with Plywood/Steel Sheathing AG-06 $11,400 • The number of exterior home walls used in the the net savings is measurable but not large as the Insulating Concrete Form AG-08,09 $13,400 construction of the safe room reduction of materials from the design is typically 1 All safe room types shown in this table are above-ground are very dependent on site-specific soil conditions and the • The type of door used limited to a reduction in reinforcing steel, connectors, (AG) types for slab-on-grade foundations. Safe rooms building materials used. or wall thickness. For both the masonry and concrete constructed in basements or on crawlspaces will differ • The type of foundation on which your home is built safe rooms, there was still a basic wall thickness that 3 See drawings in this publication for specific materials used, slightly in price based on the foundations used. needed to be provided to resist both the debris impacts sizes, and other values needed for estimating purposes. • Your location within the United States (because of and the wind loads. 2 Below-ground safe room were estimated for a 5-foot by regional variations in labor and material costs) 5-foot by 8-foot (deep) safe room. The cost included a cast- 4 Costs provided are budgetary cost estimates calculated to in-place footing and safe room top, but the safe room walls 2008 U.S. dollar values. • Whether you are building a safe room into a new were a pre-cast unit. The costs for these types of safe rooms home or retrofitting an existing home

84 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 85 SECTION III | BUILDING YOUR wind pressures. Typical and maximum dimensions How to Use the Drawings compliance with FEMA 320 and continued respect for have been provided on the drawings. The safe the storm shelter industry; it is recommended that SAFE ROOM rooms have been evaluated for and comply with the • Drawings should not be scaled to determine all plans used for the construction of safe rooms or dimensions. Your builder/contractor can use the design drawings design criteria in FEMA 361 and the shelter standard shelters be subject to a third party review for quality provided in this guide to build a safe room for any requirements set forth in the ICC-500 for residential • If there is a conflict between a dimension shown on assurance purposes. and small community shelters (shelters with less than of the wind zones shown on the map in Figure I-4. the drawings and a scaled dimension, the dimension The NSSA website (http://www.nssa.cc) contains 16 occupants). Before increasing the safe room size The design drawings provided include the details for shown on the drawing should govern. a wealth of information such as NSSA policies, or using material types, sizes, or spacings other than building five types of safe rooms: concrete, concrete evaluation procedures, grant programs, shelter news, those specified in the drawings, the changes should be • If there is a conflict between the drawings and local masonry, wood-frame, lean-to, and in-ground. Each of and guidance on shelter construction, and industry reviewed by a licensed professional structural engineer. codes, the local codes should govern as long as the these alternatives is expected to perform equally well life-safety protection provided by the safe room is links. The website also contains contact information in resisting failures caused by extreme winds. The information in this section includes the following: not lessened. It is important to note, however, that for the following different member types: The materials and connections were chosen for their • Design drawings and details for safe rooms in the structural, wall, and roof systems should not be • Producer Members – Those who manufacture or “ultimate strength,” which means that the materials basements, above the ground, and in the ground compromised because that would reduce the level of construct storm shelters and certify that shelters, are expected to resist the loads imposed on them until protection of the safe room. It is also important to designs, construction, and installation or installation • Designs for safe rooms installed on both slab-on- they or the connections between them fail. The intent note that these designs exceed most building code instructions are in compliance with the NSSA grade and crawlspace foundations of the designs is not to produce a safe room that will requirements. standard always remain completely undamaged, but rather a • General design notes and fastener and hardware • If there is a conflict among the general notes, safe room that will enable its occupants to survive an • Installer Members – Those responsible for schedules specifications, and plans, the order of precedence is extreme windstorm with little or no injuries. The safe compliance with installation instructions provided notes, then specifications, then plans. room itself may need to be extensively repaired or • Materials lists with quantities and specifications by producer members completely replaced after an extreme-wind event. If you or your builder/contractor have questions • Associate Members – Those engaged in the storm The safe room size and materials specified in the about the design drawings in this guide, call the FEMA Consumer Guide shelter industry, but who do not have direct drawings are based on principles and practices used Building Sciences helpline at (866) 222-3580 or email While this guide presents FEMA’s guidance on the responsibility for storm shelter compliance with the by structural engineering professionals and the results [email protected] for technical guidance. design and construction of residential safe rooms, NSSA standard (this includes suppliers and others of extensive testing for effects of missile impacts and FEMA does not test or certify materials or systems engaged in the storm shelter industry) used in the construction of safe rooms. Vendor claims • Professional Members – Design professionals Index of the Design Drawings of compliance with FEMA and ICC criteria should be who are capable of designing/analyzing shelters to verified through independent testing or engineering confirm compliance with applicable standards and Sheet No. Drawing No. Title analysis. The National Storm Shelter Association other professionals who support the mission of NSSA 1 of 18 T-01 Index Sheet (NSSA) is a non-profit, industry association dedicated and also contribute to safety from extreme winds to the storm shelter industry. The NSSA “administers 2 of 18 G -01 General Notes testing and engineering evaluation programs to be • Corporate Sponsors – Corporate entities with business interests in the storm shelter industry who 3 of 18 IG-01 In-Ground Safe Room – Sections and Details conducted by certified, independent entities for the purpose of issuing labels to qualified storm shelter are willing to support the programs of the NSSA 4 of 18 B-01 Basement Lean-To Safe Room producers.” In 2001, the NSSA prepared an association It is recommended that consumers pursue safe rooms standard for the design and construction of storm 5 of 18 B-02 Basement Safe Room – Corner Location or shelters (manufactured, constructed, or installed) shelters. The NSSA Association Standard will be that are per the designs provided in this publication or 6 of 18 AG-01 CMU/Concrete Alternative Plans superseded, and the new “Association Standard” will are verified with a seal from NSSA to meet the FEMA be the ICC-500 Storm Shelter Standard. The NSSA 7 of 18 AG-02 CMU/Concrete Wall Sections criteria. The NSSA is one place that prospective safe is one place a homeowner or prospective safe room room or shelter owners can look to for verification, 8 of 18 AG-03 CMU/Concrete Sections Ceiling Alternatives owner can go to seek approved product listings (for certification, and compliance. safe rooms, shelters, or components) or to verify 9 of 18 AG-04 Ventilation Details vendor claims of standards compliance for tornado and 10 of 18 AG-05 Wood-Frame Safe Room Plan – Plywood Sheathing with CMU Infill hurricane safe rooms. Safe Rooms Save Lives 11 of 18 AG-06 Wood-Frame Safe Room Plan – Plywood and Steel Wall Sheathing The NSSA is the only non-profit organization with The Oklahoma Safe Room Initiative and rebate a quality verification process and seal program. This program (http://www.gov.ok.gov/display_article. 12 of 18 AG-07 Wood-Frame Safe Room – Foundation Sections enables safe room consumers to consider the identity php?article_id=123&article_type=1) built 6,016 safe 13 of 18 AG-08 Insulating Concrete Form Plans of safe room producers with labeled, quality-verified rooms after the 1999 tornado. There were no deaths products; have an industry standard that establishes during the 2003 tornado that impacted much of the 14 of 18 AG-09 Insulating Concrete Form Sections quality requirements; and be informed and educated same area also impacted in 1999; the success directly 15 of 18 MS-01 Miscellaneous. Details on the storm shelter industry via seminars, web pages, attributable to the availability and utilization of the and responses to inquiries through the NSSA. The safe rooms. The Oklahomans in “Tornado Alley” 16 of 18 MS-02 Door Details and Signing Requirements standards to which NSSA holds its manufacturers are felt safe and protected knowing that their families 17 and 18 of 18 ML-01, 02 Materials Lists consistent with the level of protection provided by the had a safe place to go. As of March 2008, this and ICC-500 design criteria and FEMA 320. Members of other FEMA grant programs have provided over * IG = In-ground, B = Basement, AG = Above-ground the NSSA that manufacture and construct residential $260,000,000 in federal funds towards the design and safe rooms submit their designs to the NSSA for third construction of nearly 20,000 residential and over 500 party design reviews to ensure association support for community safe rooms in 23 states and territories.

86 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 87 SECTION III | BUILDING YOUR wind pressures. Typical and maximum dimensions How to Use the Drawings compliance with FEMA 320 and continued respect for have been provided on the drawings. The safe the storm shelter industry; it is recommended that SAFE ROOM rooms have been evaluated for and comply with the • Drawings should not be scaled to determine all plans used for the construction of safe rooms or dimensions. Your builder/contractor can use the design drawings design criteria in FEMA 361 and the shelter standard shelters be subject to a third party review for quality provided in this guide to build a safe room for any requirements set forth in the ICC-500 for residential • If there is a conflict between a dimension shown on assurance purposes. and small community shelters (shelters with less than of the wind zones shown on the map in Figure I-4. the drawings and a scaled dimension, the dimension The NSSA website (http://www.nssa.cc) contains 16 occupants). Before increasing the safe room size The design drawings provided include the details for shown on the drawing should govern. a wealth of information such as NSSA policies, or using material types, sizes, or spacings other than building five types of safe rooms: concrete, concrete evaluation procedures, grant programs, shelter news, those specified in the drawings, the changes should be • If there is a conflict between the drawings and local masonry, wood-frame, lean-to, and in-ground. Each of and guidance on shelter construction, and industry reviewed by a licensed professional structural engineer. codes, the local codes should govern as long as the these alternatives is expected to perform equally well life-safety protection provided by the safe room is links. The website also contains contact information in resisting failures caused by extreme winds. The information in this section includes the following: not lessened. It is important to note, however, that for the following different member types: The materials and connections were chosen for their • Design drawings and details for safe rooms in the structural, wall, and roof systems should not be • Producer Members – Those who manufacture or “ultimate strength,” which means that the materials basements, above the ground, and in the ground compromised because that would reduce the level of construct storm shelters and certify that shelters, are expected to resist the loads imposed on them until protection of the safe room. It is also important to designs, construction, and installation or installation • Designs for safe rooms installed on both slab-on- they or the connections between them fail. The intent note that these designs exceed most building code instructions are in compliance with the NSSA grade and crawlspace foundations of the designs is not to produce a safe room that will requirements. standard always remain completely undamaged, but rather a • General design notes and fastener and hardware • If there is a conflict among the general notes, safe room that will enable its occupants to survive an • Installer Members – Those responsible for schedules specifications, and plans, the order of precedence is extreme windstorm with little or no injuries. The safe compliance with installation instructions provided notes, then specifications, then plans. room itself may need to be extensively repaired or • Materials lists with quantities and specifications by producer members completely replaced after an extreme-wind event. If you or your builder/contractor have questions • Associate Members – Those engaged in the storm The safe room size and materials specified in the about the design drawings in this guide, call the FEMA Consumer Guide shelter industry, but who do not have direct drawings are based on principles and practices used Building Sciences helpline at (866) 222-3580 or email While this guide presents FEMA’s guidance on the responsibility for storm shelter compliance with the by structural engineering professionals and the results [email protected] for technical guidance. design and construction of residential safe rooms, NSSA standard (this includes suppliers and others of extensive testing for effects of missile impacts and FEMA does not test or certify materials or systems engaged in the storm shelter industry) used in the construction of safe rooms. Vendor claims • Professional Members – Design professionals Index of the Design Drawings of compliance with FEMA and ICC criteria should be who are capable of designing/analyzing shelters to verified through independent testing or engineering confirm compliance with applicable standards and Sheet No. Drawing No. Title analysis. The National Storm Shelter Association other professionals who support the mission of NSSA 1 of 18 T-01 Index Sheet (NSSA) is a non-profit, industry association dedicated and also contribute to safety from extreme winds to the storm shelter industry. The NSSA “administers 2 of 18 G -01 General Notes testing and engineering evaluation programs to be • Corporate Sponsors – Corporate entities with business interests in the storm shelter industry who 3 of 18 IG-01 In-Ground Safe Room – Sections and Details conducted by certified, independent entities for the purpose of issuing labels to qualified storm shelter are willing to support the programs of the NSSA 4 of 18 B-01 Basement Lean-To Safe Room producers.” In 2001, the NSSA prepared an association It is recommended that consumers pursue safe rooms standard for the design and construction of storm 5 of 18 B-02 Basement Safe Room – Corner Location or shelters (manufactured, constructed, or installed) shelters. The NSSA Association Standard will be that are per the designs provided in this publication or 6 of 18 AG-01 CMU/Concrete Alternative Plans superseded, and the new “Association Standard” will are verified with a seal from NSSA to meet the FEMA be the ICC-500 Storm Shelter Standard. The NSSA 7 of 18 AG-02 CMU/Concrete Wall Sections criteria. The NSSA is one place that prospective safe is one place a homeowner or prospective safe room room or shelter owners can look to for verification, 8 of 18 AG-03 CMU/Concrete Sections Ceiling Alternatives owner can go to seek approved product listings (for certification, and compliance. safe rooms, shelters, or components) or to verify 9 of 18 AG-04 Ventilation Details vendor claims of standards compliance for tornado and 10 of 18 AG-05 Wood-Frame Safe Room Plan – Plywood Sheathing with CMU Infill hurricane safe rooms. Safe Rooms Save Lives 11 of 18 AG-06 Wood-Frame Safe Room Plan – Plywood and Steel Wall Sheathing The NSSA is the only non-profit organization with The Oklahoma Safe Room Initiative and rebate a quality verification process and seal program. This program (http://www.gov.ok.gov/display_article. 12 of 18 AG-07 Wood-Frame Safe Room – Foundation Sections enables safe room consumers to consider the identity php?article_id=123&article_type=1) built 6,016 safe 13 of 18 AG-08 Insulating Concrete Form Plans of safe room producers with labeled, quality-verified rooms after the 1999 tornado. There were no deaths products; have an industry standard that establishes during the 2003 tornado that impacted much of the 14 of 18 AG-09 Insulating Concrete Form Sections quality requirements; and be informed and educated same area also impacted in 1999; the success directly 15 of 18 MS-01 Miscellaneous. Details on the storm shelter industry via seminars, web pages, attributable to the availability and utilization of the and responses to inquiries through the NSSA. The safe rooms. The Oklahomans in “Tornado Alley” 16 of 18 MS-02 Door Details and Signing Requirements standards to which NSSA holds its manufacturers are felt safe and protected knowing that their families 17 and 18 of 18 ML-01, 02 Materials Lists consistent with the level of protection provided by the had a safe place to go. As of March 2008, this and ICC-500 design criteria and FEMA 320. Members of other FEMA grant programs have provided over * IG = In-ground, B = Basement, AG = Above-ground the NSSA that manufacture and construct residential $260,000,000 in federal funds towards the design and safe rooms submit their designs to the NSSA for third construction of nearly 20,000 residential and over 500 party design reviews to ensure association support for community safe rooms in 23 states and territories.

86 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 87 Below are just a few examples of how FEMA 320 conditions, I couldn’t see running three dogs over the seriously and say ‘Well if it could happen to my mom inside the house.” safe rooms have saved the lives of people impacted carpet.” Also, the house was intended to be their last and dad, it could happen to me.” In December 2000, the Staleys’ new home was ready. by extreme-wind events. With proper installation, and they wanted it to be a certain way. “It would have Van Valkenburg started the process of building his safe Shortly after moving in, they had an aboveground storm shelters and safe rooms serve as protection been too much structural change,” Karen said. “I didn’t room in 2001. He called his local emergency manager safe room constructed on the back patio. The concrete from injury or death caused by the dangerous forces want to change my basic plans of the house the floor and enrolled in the Alabama safe room program room has 8-inch thick walls, an 18-inch thick ceiling, of extreme winds. They can also relieve some of the plan I liked. I didn’t want to modify it to accommodate sponsored by FEMA and the Alabama Emergency a 10-inch foundation, and a sliding entry door made anxiety created by the threat of an oncoming tornado everyone.” Management Agency. Actual construction of the safe of 12-gauge steel with 3/4-inch plywood on each side. or hurricane. The decision to build or purchase a While the main house is mostly handicapped room took place over 8 months in 2002. FEMA paid The safe room is equipped with battery-powered lights safe room should include notifying local emergency accessible, it still would have been difficult to construct 75 percent of the cost to build it, $3,500, through its and a battery-powered television. managers and family members or others outside the a safe room inside the house and have someone in a Hazard Mitigation Grant Program (HMGP). “My local immediate area. This will allow emergency personnel When the warning sirens sounded on May 8, 2003, wheelchair enter it without requiring assistance down emergency managers came out to look at the safe room to quickly free the exit should it become blocked by Don took shelter in the safe room along with his the stairs. The safe room has a ramp, making it easily while it was under construction and took pictures. I debris. For additional information on these and other dog and two cats to ride out the storm feeling very accessible for anyone confined to a wheelchair. “It is had to show an itemized break down of everything, safe room “success stories,” see the FEMA websites protected and safe. “I was watching it on TV in there,” a retirement home for my husband and I and one of and show the cost to substantiate what I paid for he recalled. “I could see it was coming my way and I listed below. us could end up in a wheelchair someday, [whether] it. Then they gave me the money,” Van Valkenburg could hear it coming. I could hear the roar. That’s a permanently or temporarily,” Karen said. “Based stated. He also spent more of his own money to add a Baxter County, Arkansas – On February 5, 2008, sound you never forget.” when a tornado visited the town of Gassville, Arkansas, on Murphy’s Law, that’s when a tornado would hit. second entry way to the room, in the event the other Jeanann Quattlebaum felt a certain calmness. Less We just decided to have everything handicapped entry is blocked, a drainage system, and a generator in When he emerged from the shelter, he found his than 10 months prior, she and her husband, Robert, accessible.” the back of his house that kicks in if there is a loss of house in shambles with the roof ripped off. Other power. houses on the street were also heavily damaged or had purchased a storm shelter. The Quattlebaums had Karen and her husband based their safe room model destroyed. The Staleys used their safe room following been living in their subdivision for seven years. They on FEMA regulations and just added a few additional The safe room got its first test the following spring. the tornado to store and protect belongings they had purchased their home, which was not equipped with a measures of their own. The room is a reinforced Van Valkenburg, his wife, two children, and three salvaged. The Staleys’ home was among the more than safe room, from an area builder. concrete structure with French drains. The front of the dogs stayed in it when a storm system came through 300 homes destroyed in the city that day. Whereas a cellar faces north and wings are extended on the sides and a tornado touched down in the area. “We heard Arkansas is one of several states in “Tornado Alley,” a severe tornado hit the city in May 1999 and claimed and top to hold back the clay. Four feet of earth also the sirens and went down there in the middle of the term used to describe a broad area of relatively high 44 lives, there were no deaths in the 2003 tornado. The cover the roof of the cellar. Stucco, paint, and water night,” says Van Valkenburg “I have my pager from the tornado occurrences in the central United States. The absence of fatalities is being attributed to community sealer was applied to the concrete and a metal porch fire department, and when it goes off I know we have state ranks fourth, after Texas, Oklahoma, and Kansas, preparedness, improved early warning systems, and was built on top of hickory beams to prevent rain severe weather coming into Autauga County. If they with tornadoes that are F3 and higher. the many safe rooms and shelters that have been built. from pouring inside whenever the door was opened. say tornado warning we go there.” In 2004, his family Staley sums it all up, “The safe room saved my life, it The Arkansas Residential Safe Room Program assists No moisture is likely to leak into the cellar. Karen said used the shelter again, but for protection from two came through with flying colors. It’s worth a million Arkansas homeowners who choose to install a shelter she intended to build it that way because she strongly hurricanes. Twice during the summer, his family took bucks to me.” or safe room on their property. The program covers up despises a “damp, musty basement.” shelter in their safe room during Hurricanes Ivan and to 50 percent of the cost and installation, not to exceed Dennis. http://www.fema.gov/mitigationbp/brief. The project probably cost more than what it normally $1,000.00, for shelters or safe rooms built on or after do?mitssId=761 January 21, 1999. The Quattlebaums’ storm shelter was would have if they had built it inside their home and The safe room is 11-by-12 feet and is below the ground purchased at a cost of $2,000.00. The circular concrete without all the added weather protection, but Karen under a new wing that Van Valkenburg built onto his Lowndes County (MS) – North of Columbus, structure is 10 feet in diameter and stands 5 feet tall. It was willing to make the sacrifice. She also wanted the house for his elderly father-in-law. It is built to be a Mississippi is the community of Caledonia. Recently, has the capacity to seat six to eight individuals. During room – measured at 10 by 12 feet – to be large enough natural extension of the house. “I knew because of my that town has experienced a bit of growth; folks have the tornado event of February 5, 2008, it housed six for her, her husband, and their pets. “I just wanted to wife being claustrophobic, I had to design it where moved in and built smaller homes to enjoy a more as the tornado touched the lives of Gassville residents. take FEMA’s requirements [design criteria] and enhance it looked like a room or she wouldn’t go into it,” he relaxed country atmosphere. And several United States The tornado left behind one fatality and damages to them,” she said. “I probably have exceeded their said. The room is made of reinforced concrete and has Air Force retirees have settled there, following a tour of homes and property, which ranged from minimal to requirements … [so] yes, there was an added expense steel doors that lock from the inside. Van Valkenburg duty at Columbus AFB. to have it bigger. But it really didn’t add that much. It has also equipped it with a big, sturdy bed, battery extensive. But there have been several storms in that area. In was worth it to me. That was a personal call. Everybody powered televisions, water, non-perishable foods, a November 2002, a tornado struck and damaged homes http://www.fema.gov/mitigationbp/brief. has to make them.” first aid kit, power tools and the negatives to all family and property there as well as other county locations. do?mitssId=5466 photos. “We can come out of there and we can start http://www.fema.gov/mitigationbp/brief. The State of Mississippi had already recognized the life again,” said Van Valkenburg. “That’s what it is all Oklahoma City, Oklahoma – When Karen and her do?mitssId=1345 need for storm protection earlier and had instituted about, coming out of the safe room and being able to husband built their retirement home in 2002, they a tornado safety program, “A Safe Place to Go”. With Autauga County, Alabama – After seeing the live.” were determined to build a protective safe room this declaration, several storm shelter installations destruction of his parents’ home, an Autauga equipped with the necessary amenities and materials in http://www.fema.gov/mitigationbp/brief. were funded by a FEMA Hazard Mitigation Grant. The County firefighter decided that it is up to him to the event of a devastating tornado. Instead of building do?mitssId=1646 Wayne Duncan family in Caledonia applied and were keep himself and his family safe from storms. Robert the room inside their home like most people, they reimbursed according to FEMA/MEMA guidelines. An Van Valkenburg, 52, decided to look into building a Moore, Oklahoma – Don Staley and his family are decided to construct it 20 feet away from the house, underground safe room was located just outside the tornado safe room for his home after his parents’ home no strangers to storms and tornados. Their first home and to build it large enough for their extended family. carport in the backyard, providing welcome peace of was destroyed by a tornado spawned by Hurricane was hit by a tornado in October 1998 and suffered mind. “I believe my pets are part of my family,” Karen said, Andrew. “I grew up in that house and it was lost during minor damage, but was destroyed by another tornado referring to her three dogs – two Airedales and a Blue Hurricane Andrew, so I take this stuff very seriously,” on May 3, 1999. They rode out both storms inside About 2:00 pm, January 10, 2008, the storm roared Heeler – and bird – a Scarlet Macaw. “I wasn’t going to says Van Valkenburg. He adds, “When it impacts your the house. “It was such a frightening sound,” he said. across Columbus AFB and a tornado touched down in run three dogs through the house. Because of weather family, and you see how it affects them, you take it “We decided we weren’t going to ride out another one Caledonia, again. It nearly destroyed the local school,

88 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 89 Below are just a few examples of how FEMA 320 conditions, I couldn’t see running three dogs over the seriously and say ‘Well if it could happen to my mom inside the house.” safe rooms have saved the lives of people impacted carpet.” Also, the house was intended to be their last and dad, it could happen to me.” In December 2000, the Staleys’ new home was ready. by extreme-wind events. With proper installation, and they wanted it to be a certain way. “It would have Van Valkenburg started the process of building his safe Shortly after moving in, they had an aboveground storm shelters and safe rooms serve as protection been too much structural change,” Karen said. “I didn’t room in 2001. He called his local emergency manager safe room constructed on the back patio. The concrete from injury or death caused by the dangerous forces want to change my basic plans of the house the floor and enrolled in the Alabama safe room program room has 8-inch thick walls, an 18-inch thick ceiling, of extreme winds. They can also relieve some of the plan I liked. I didn’t want to modify it to accommodate sponsored by FEMA and the Alabama Emergency a 10-inch foundation, and a sliding entry door made anxiety created by the threat of an oncoming tornado everyone.” Management Agency. Actual construction of the safe of 12-gauge steel with 3/4-inch plywood on each side. or hurricane. The decision to build or purchase a While the main house is mostly handicapped room took place over 8 months in 2002. FEMA paid The safe room is equipped with battery-powered lights safe room should include notifying local emergency accessible, it still would have been difficult to construct 75 percent of the cost to build it, $3,500, through its and a battery-powered television. managers and family members or others outside the a safe room inside the house and have someone in a Hazard Mitigation Grant Program (HMGP). “My local immediate area. This will allow emergency personnel When the warning sirens sounded on May 8, 2003, wheelchair enter it without requiring assistance down emergency managers came out to look at the safe room to quickly free the exit should it become blocked by Don took shelter in the safe room along with his the stairs. The safe room has a ramp, making it easily while it was under construction and took pictures. I debris. For additional information on these and other dog and two cats to ride out the storm feeling very accessible for anyone confined to a wheelchair. “It is had to show an itemized break down of everything, safe room “success stories,” see the FEMA websites protected and safe. “I was watching it on TV in there,” a retirement home for my husband and I and one of and show the cost to substantiate what I paid for he recalled. “I could see it was coming my way and I listed below. us could end up in a wheelchair someday, [whether] it. Then they gave me the money,” Van Valkenburg could hear it coming. I could hear the roar. That’s a permanently or temporarily,” Karen said. “Based stated. He also spent more of his own money to add a Baxter County, Arkansas – On February 5, 2008, sound you never forget.” when a tornado visited the town of Gassville, Arkansas, on Murphy’s Law, that’s when a tornado would hit. second entry way to the room, in the event the other Jeanann Quattlebaum felt a certain calmness. Less We just decided to have everything handicapped entry is blocked, a drainage system, and a generator in When he emerged from the shelter, he found his than 10 months prior, she and her husband, Robert, accessible.” the back of his house that kicks in if there is a loss of house in shambles with the roof ripped off. Other power. houses on the street were also heavily damaged or had purchased a storm shelter. The Quattlebaums had Karen and her husband based their safe room model destroyed. The Staleys used their safe room following been living in their subdivision for seven years. They on FEMA regulations and just added a few additional The safe room got its first test the following spring. the tornado to store and protect belongings they had purchased their home, which was not equipped with a measures of their own. The room is a reinforced Van Valkenburg, his wife, two children, and three salvaged. The Staleys’ home was among the more than safe room, from an area builder. concrete structure with French drains. The front of the dogs stayed in it when a storm system came through 300 homes destroyed in the city that day. Whereas a cellar faces north and wings are extended on the sides and a tornado touched down in the area. “We heard Arkansas is one of several states in “Tornado Alley,” a severe tornado hit the city in May 1999 and claimed and top to hold back the clay. Four feet of earth also the sirens and went down there in the middle of the term used to describe a broad area of relatively high 44 lives, there were no deaths in the 2003 tornado. The cover the roof of the cellar. Stucco, paint, and water night,” says Van Valkenburg “I have my pager from the tornado occurrences in the central United States. The absence of fatalities is being attributed to community sealer was applied to the concrete and a metal porch fire department, and when it goes off I know we have state ranks fourth, after Texas, Oklahoma, and Kansas, preparedness, improved early warning systems, and was built on top of hickory beams to prevent rain severe weather coming into Autauga County. If they with tornadoes that are F3 and higher. the many safe rooms and shelters that have been built. from pouring inside whenever the door was opened. say tornado warning we go there.” In 2004, his family Staley sums it all up, “The safe room saved my life, it The Arkansas Residential Safe Room Program assists No moisture is likely to leak into the cellar. Karen said used the shelter again, but for protection from two came through with flying colors. It’s worth a million Arkansas homeowners who choose to install a shelter she intended to build it that way because she strongly hurricanes. Twice during the summer, his family took bucks to me.” or safe room on their property. The program covers up despises a “damp, musty basement.” shelter in their safe room during Hurricanes Ivan and to 50 percent of the cost and installation, not to exceed Dennis. http://www.fema.gov/mitigationbp/brief. The project probably cost more than what it normally $1,000.00, for shelters or safe rooms built on or after do?mitssId=761 January 21, 1999. The Quattlebaums’ storm shelter was would have if they had built it inside their home and The safe room is 11-by-12 feet and is below the ground purchased at a cost of $2,000.00. The circular concrete without all the added weather protection, but Karen under a new wing that Van Valkenburg built onto his Lowndes County (MS) – North of Columbus, structure is 10 feet in diameter and stands 5 feet tall. It was willing to make the sacrifice. She also wanted the house for his elderly father-in-law. It is built to be a Mississippi is the community of Caledonia. Recently, has the capacity to seat six to eight individuals. During room – measured at 10 by 12 feet – to be large enough natural extension of the house. “I knew because of my that town has experienced a bit of growth; folks have the tornado event of February 5, 2008, it housed six for her, her husband, and their pets. “I just wanted to wife being claustrophobic, I had to design it where moved in and built smaller homes to enjoy a more as the tornado touched the lives of Gassville residents. take FEMA’s requirements [design criteria] and enhance it looked like a room or she wouldn’t go into it,” he relaxed country atmosphere. And several United States The tornado left behind one fatality and damages to them,” she said. “I probably have exceeded their said. The room is made of reinforced concrete and has Air Force retirees have settled there, following a tour of homes and property, which ranged from minimal to requirements … [so] yes, there was an added expense steel doors that lock from the inside. Van Valkenburg duty at Columbus AFB. to have it bigger. But it really didn’t add that much. It has also equipped it with a big, sturdy bed, battery extensive. But there have been several storms in that area. In was worth it to me. That was a personal call. Everybody powered televisions, water, non-perishable foods, a November 2002, a tornado struck and damaged homes http://www.fema.gov/mitigationbp/brief. has to make them.” first aid kit, power tools and the negatives to all family and property there as well as other county locations. do?mitssId=5466 photos. “We can come out of there and we can start http://www.fema.gov/mitigationbp/brief. The State of Mississippi had already recognized the life again,” said Van Valkenburg. “That’s what it is all Oklahoma City, Oklahoma – When Karen and her do?mitssId=1345 need for storm protection earlier and had instituted about, coming out of the safe room and being able to husband built their retirement home in 2002, they a tornado safety program, “A Safe Place to Go”. With Autauga County, Alabama – After seeing the live.” were determined to build a protective safe room this declaration, several storm shelter installations destruction of his parents’ home, an Autauga equipped with the necessary amenities and materials in http://www.fema.gov/mitigationbp/brief. were funded by a FEMA Hazard Mitigation Grant. The County firefighter decided that it is up to him to the event of a devastating tornado. Instead of building do?mitssId=1646 Wayne Duncan family in Caledonia applied and were keep himself and his family safe from storms. Robert the room inside their home like most people, they reimbursed according to FEMA/MEMA guidelines. An Van Valkenburg, 52, decided to look into building a Moore, Oklahoma – Don Staley and his family are decided to construct it 20 feet away from the house, underground safe room was located just outside the tornado safe room for his home after his parents’ home no strangers to storms and tornados. Their first home and to build it large enough for their extended family. carport in the backyard, providing welcome peace of was destroyed by a tornado spawned by Hurricane was hit by a tornado in October 1998 and suffered mind. “I believe my pets are part of my family,” Karen said, Andrew. “I grew up in that house and it was lost during minor damage, but was destroyed by another tornado referring to her three dogs – two Airedales and a Blue Hurricane Andrew, so I take this stuff very seriously,” on May 3, 1999. They rode out both storms inside About 2:00 pm, January 10, 2008, the storm roared Heeler – and bird – a Scarlet Macaw. “I wasn’t going to says Van Valkenburg. He adds, “When it impacts your the house. “It was such a frightening sound,” he said. across Columbus AFB and a tornado touched down in run three dogs through the house. Because of weather family, and you see how it affects them, you take it “We decided we weren’t going to ride out another one Caledonia, again. It nearly destroyed the local school,

88 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Taking Shelter from the Storm: Building a Safe Room | 89 causing damage to several homes. Mrs. Lena Duncan, The three basic objectives to help ensure a successful with her daughter, son-in-law, and the grandbaby, program were public education, financial assistance, ran from the house into the underground safe room and quality control. First, the State of Oklahoma and waited for the winds and rain to stop. The house and FEMA kicked off an extensive Public Education was heavily damaged, but the family was safe in their Campaign that encompassed a wide range of outreach shelter. projects using public service announcements through radio, television, and print. Books, resources, and The Hazard Mitigation Grant Program (HMGP) educational materials were distributed to the residents remains in effect in Mississippi, following the Katrina and communities, while speakers and meetings were declaration. Lowndes County is participating in this Review of Structural Materials & Methods used to reach the general public. Grant. This summer, the Duncan family plan to relocate, down the road, in a new home. This new Next, the safe room had to be financially affordable for Home Building in the U.S.: 1900-2000 house will be built with a planned inclusion of a safe to the people. Federal and State agencies developed room, following the guidelines of FEMA 320. Still a first-in-the-Nation safe room rebate program called working in the Lowndes County Courthouse, Lena “Oklahoma Can Survive” to help cover the cost of Duncan encourages anyone who asks about tornado constructing safe rooms. A $2,000 rebate was offered AIA CES Course Number: AIAPDH117 safety to go talk with the Lowndes County Emergency to property owners for the building of a safe room Management officials about tornado preparedness and [Editorial note: At the time of this program, FEMA safety. estimated the safe room cost of an above-ground Course Description: safe room was approximately $3,500.] The rebates One final example discusses the program that funded were given in three phases. Phase 1 provided rebates This study examines the evolvement of U.S. housing construction during the 20th century. several of the Oklahoma safe rooms mentioned above: to those people whose homes were destroyed or Of particular interest are changes in construction practices associated with the materials and Oklahoma City, Oklahoma - On May 9, 2003, substantially damaged in the designated disaster area; methods used in home building that affect structural performance. The purpose is to benchmark tornadoes swooped across Oklahoma City’s “Tornado Phase 2 provided rebates to people with damaged housing structural characteristics (as implied by historic practice), to identify significant Alley.” The tornadoes’ path was virtually the same homes in the designated disaster area; and Phase 3 changes that have occurred, and to provide an objective resource for discussion and evaluation as the one that struck 4 years prior. Oklahoma has rebates were provided to anyone in the state who of structural design implications. Other related interests, such as construction quality, are also historically been subject to destructive and deadly wanted a safe room. considered. tornados and high winds. After the 1999 tornado, 44 Finally, minimal performance criteria guidelines were persons died, 800 were injured and over 6,000 homes enforced for proper safe room construction. FEMA 320 were damaged or destroyed. Learning Units: was used as a construction guideline to provide all the In order to make Oklahoma a safer place to live, information a contractor needed to build a safe room. 3.0 LU/HSW the state launched a Safe Room Initiative Program. FEMA then used performance criteria based on FEMA Oklahoma was the first state to promote and 320. An engineer was retained to assist the state in Learning Objective 1: implement a Statewide residential safe room initiative technical support, and help contractors and educating to build safer communities. The safe room initiative the general public about choosing a safe room Upon completion of this course, the student will be aware of the recent history of home building was implemented by the State of Oklahoma with construction contractor and helping homeowners with with respect to relevant technical data on structural performance. mitigation funds made available by FEMA through the complaints against contractor performances. HMGP. This program funded the building of 6,016 safe Learning Objective 2: rooms across the state. The student will understand that the process of improving current housing value should include periodic evaluation to confirm past successes and to consider the ramifications of past decisions.

Learning Objective 3: The student will be able to use these findings to help foster future advancement in the interest of even better housing value.

Learning Objective 4: The student will learn there have been many changes in materials and tools that require more precision in construction, resulting in a greater potential for error, particularly in connections. Accordingly, more attention should be given to connection details that balance structural needs with the intuition and capability of the tradesperson.

90 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 91 causing damage to several homes. Mrs. Lena Duncan, The three basic objectives to help ensure a successful with her daughter, son-in-law, and the grandbaby, program were public education, financial assistance, ran from the house into the underground safe room and quality control. First, the State of Oklahoma and waited for the winds and rain to stop. The house and FEMA kicked off an extensive Public Education was heavily damaged, but the family was safe in their Campaign that encompassed a wide range of outreach shelter. projects using public service announcements through radio, television, and print. Books, resources, and The Hazard Mitigation Grant Program (HMGP) educational materials were distributed to the residents remains in effect in Mississippi, following the Katrina and communities, while speakers and meetings were declaration. Lowndes County is participating in this Review of Structural Materials & Methods used to reach the general public. Grant. This summer, the Duncan family plan to relocate, down the road, in a new home. This new Next, the safe room had to be financially affordable for Home Building in the U.S.: 1900-2000 house will be built with a planned inclusion of a safe to the people. Federal and State agencies developed room, following the guidelines of FEMA 320. Still a first-in-the-Nation safe room rebate program called working in the Lowndes County Courthouse, Lena “Oklahoma Can Survive” to help cover the cost of Duncan encourages anyone who asks about tornado constructing safe rooms. A $2,000 rebate was offered AIA CES Course Number: AIAPDH117 safety to go talk with the Lowndes County Emergency to property owners for the building of a safe room Management officials about tornado preparedness and [Editorial note: At the time of this program, FEMA safety. estimated the safe room cost of an above-ground Course Description: safe room was approximately $3,500.] The rebates One final example discusses the program that funded were given in three phases. Phase 1 provided rebates This study examines the evolvement of U.S. housing construction during the 20th century. several of the Oklahoma safe rooms mentioned above: to those people whose homes were destroyed or Of particular interest are changes in construction practices associated with the materials and Oklahoma City, Oklahoma - On May 9, 2003, substantially damaged in the designated disaster area; methods used in home building that affect structural performance. The purpose is to benchmark tornadoes swooped across Oklahoma City’s “Tornado Phase 2 provided rebates to people with damaged housing structural characteristics (as implied by historic practice), to identify significant Alley.” The tornadoes’ path was virtually the same homes in the designated disaster area; and Phase 3 changes that have occurred, and to provide an objective resource for discussion and evaluation as the one that struck 4 years prior. Oklahoma has rebates were provided to anyone in the state who of structural design implications. Other related interests, such as construction quality, are also historically been subject to destructive and deadly wanted a safe room. considered. tornados and high winds. After the 1999 tornado, 44 Finally, minimal performance criteria guidelines were persons died, 800 were injured and over 6,000 homes enforced for proper safe room construction. FEMA 320 were damaged or destroyed. Learning Units: was used as a construction guideline to provide all the In order to make Oklahoma a safer place to live, information a contractor needed to build a safe room. 3.0 LU/HSW the state launched a Safe Room Initiative Program. FEMA then used performance criteria based on FEMA Oklahoma was the first state to promote and 320. An engineer was retained to assist the state in Learning Objective 1: implement a Statewide residential safe room initiative technical support, and help contractors and educating to build safer communities. The safe room initiative the general public about choosing a safe room Upon completion of this course, the student will be aware of the recent history of home building was implemented by the State of Oklahoma with construction contractor and helping homeowners with with respect to relevant technical data on structural performance. mitigation funds made available by FEMA through the complaints against contractor performances. HMGP. This program funded the building of 6,016 safe Learning Objective 2: rooms across the state. The student will understand that the process of improving current housing value should include periodic evaluation to confirm past successes and to consider the ramifications of past decisions.

Learning Objective 3: The student will be able to use these findings to help foster future advancement in the interest of even better housing value.

90 | Taking Shelter from the Storm: Building a Safe Room ARCHITECTURE ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 91 1.0 GENERAL HOUSING CHARACTERISTICS INTRODUCTION Based on U.S. Census data, the Builder Practices Survey, Americans have greater access to better housing Housing at the Millennium: Facts, Figures, and Trends, today than ever before. While modern housing and other sources (see Bibliography), a synopsis may be considered to be better than in the past, the of American housing in the 20th century may be process of improving housing value should include constructed for each of the following periods: periodic evaluation to confirm past successes, consider the ramifications of past decisions, and foster future advancement in the interest of even 1.1 EARLY 1900s better housing value. The following characteristics describe a typical home This paper examines the evolvement of U.S. and the housing market in 1900: housing construction during the 20th century. Population: 76 million (40 percent urban, Of particular interest are changes in construction 60 percent rural) practices associated with the materials and methods Median family income: $490 used in home building that affect structural 1 performance. The purpose is to benchmark housing New home price: average unknown structural characteristics (as implied by historic Type of purchase: typically cash practice), to identify significant changes that have Ownership rate: 46 percent occurred, and to provide an objective resource Total housing units: 16 million for discussion and evaluation of structural design Number of annual housing starts: 189,000 implications. Other related interests, such as (65 percent single-family) construction quality, are also considered. Average size (starts only): less than 1,000 sq. ft. Home building has always been rooted in practical Stories: One to two stories applications of basic technology. Therefore, this Bedrooms: 2 to 3 study attempts to align the practical aspects of home building and its history with relevant Bathrooms: 0 or 1 technical data on structural performance. When 1 Based on Housing at the Millennium: Facts, Figures, and available, statistics are cited with respect to Trends, the average new home cost was less than $5,000. housing styles, size, materials, and relevant However, this estimate is potentially skewed in that many structural aspects. Where reliable statistical data is people could not afford a “house” of the nature considered in unavailable, selected documents that define typical the study. Based on Sears, Roebuck, and Co. catalogue prices practices are used to arrive at reasonable historic at the turn of the century, a typical house cost may have profiles of housing construction and structural ranged from $1,000 to $2,000, including land. characteristics. To a limited degree, personal interviews of home builders with experience dating The front elevation and floor plan of a typical home as far back as 1917 were conducted to compare with produced in 1900 is shown in Figure 1. Good examples information found in the literature. of traditional housing styles and architectural plans in the early 1900s are found in catalogues produced The study focuses on structural aspects of housing by Sears, Roebuck and Co., a major producer of construction and breaks them into three periods of traditional American kit homes from about 1910 into time: early 1900s, mid-1900s, and late 1900s. While the early 1930s (see Bibliography). Likewise, it should it is recognized that change usually occurs slowly be recognized that a large portion of the public lived and that practices vary regionally, an attempt is in rural areas that were not subject to municipal made to typify relevant housing construction data building codes, and housing needs were likely fulfilled and practices in each period. The following sections in a variety of ways that may not be well documented address: in the popular literature on housing construction. • General Housing Characteristics, For example, in Cotton Field’s No More it is stated • Design Loads, that “more than half of the farmers lived in one-and • Foundation Construction, two-room shacks that had not been whitewashed or • Wood-Frame Construction, and painted for many years, if ever. Many of these houses • Construction Quality. had holes in the roof, wall, and floor.” Further, U.S. Census data for 1900 reports that the value of land Additional information on thermal insulation and buildings per farm in eleven Southern states materials and methods are reported in Appendix A ranged from $600 to $2,000. By contrast, the values as a matter of special interest. for Indiana and Kansas were $6,550 and $3,718, respectively. Thus, living conditions and housing varied widely in the early 1900s.

92 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE 1.0 GENERAL HOUSING CHARACTERISTICS INTRODUCTION Based on U.S. Census data, the Builder Practices Survey, Americans have greater access to better housing Housing at the Millennium: Facts, Figures, and Trends, today than ever before. While modern housing and other sources (see Bibliography), a synopsis may be considered to be better than in the past, the of American housing in the 20th century may be process of improving housing value should include constructed for each of the following periods: periodic evaluation to confirm past successes, consider the ramifications of past decisions, and foster future advancement in the interest of even 1.1 EARLY 1900s better housing value. The following characteristics describe a typical home 2 This paper examines the evolvement of U.S. and the housing market in 1900: Figure 1. Profile home in 1900 (2 story).2 Figure 1. Profile home in 1900 (2 story). housing construction during the 20th century. Population: 76 million (40 percent urban, 2First floor plan is similar to size and shape of a small one-story home. Of particular interest are changes in construction 60 percent rural) practices associated with the materials and methods Median family income: $490 used in home building that affect structural 1.2 MID-1900S 1 performance. The purpose is to benchmark housing New home price: average unknown structural characteristics (as implied by historic Type of purchase: typically cash The following1.2 characteristics MID-1900s describe a typical home and the housing marketBy inthe 1950: mid-1900s, the use of standardized products, materials, and methods of constructing homes had practice), to identify significant changes that have Ownership rate: 46 percent The following characteristics describe a typical home become fairly mature. In particular, lumber grading occurred, and to provide an objective resource Total housing units: 16 million Population: 150 million (64 percent urban, 36 percent rural) for discussion and evaluation of structural design and the housing market in 1950: and sizes had become essentially uniform across Number of annual housing starts: 189,000 implications. Other related interests, such as Median Population:family income: 150 million (64$3,319 percent urban, the country. Much of the standardization in home (65 percent single-family) construction quality, are also considered. New home price:36 percent rural) $11,000 building may be attributed to the Federal Housing Average size (starts only): less than 1,000 sq. ft. Administration (current day Department of Housing Type ofMedian purchase: family income: $3,319FHA mortgage, 4.25 percent (few options) Home building has always been rooted in practical Stories: One to two stories Ownership rate: 55 percent and Urban Development) with its Minimum Property applications of basic technology. Therefore, this New home price: $11,000 Bedrooms: 2 to 3 Requirements (MPRs) which were applied across the study attempts to align the practical aspects Total housingType ofunits: purchase: FHA mortgage,43 million 4.25 percent country following WWII, and which were eventually Bathrooms: 0 or 1 of home building and its history with relevant Number of housing(few options) starts: 1.95 million (85 percent singlesuperceded-family) by a first edition of theMinimum Property technical data on structural performance. When 1 Based on Housing at the Millennium: Facts, Figures, and AverageOwnership size (starts only):rate: 55 percent1,000 sq.ft. Standards (MPS) in 1958. At this point, the older “rules- available, statistics are cited with respect to Trends, the average new home cost was less than $5,000. Stories:Total housing units: 43 million86 percent one story; 14 percentof-thumb” two or weremore giving way to prescriptive construction housing styles, size, materials, and relevant However, this estimate is potentially skewed in that many Bedrooms:Number of housing starts: 21.95 (66 millionpercent); 3 (33 percent)requirements (e.g., span tables, construction structural aspects. Where reliable statistical data is people could not afford a “house” of the nature considered in Bathrooms: (85 percent single-family)1-1/2 or less (96 percent) specifications, etc.) that were based on practical as unavailable, selected documents that define typical the study. Based on Sears, Roebuck, and Co. catalogue prices well as basic technical (engineering) criteria. Newer Average size (starts only): 1,000 sq. ft. practices are used to arrive at reasonable historic at the turn of the century, a typical house cost may have By the mid-1900s,Garage: the use of standardized products,1 car (41 materials, percent); and 0 (53methods percent)materials of constructing such as plywood homes had sheathing become were fairly addressed mature. asIn ranged from $1,000 to $2,000, including land. Stories: 86 percent one story; 14 percent two or more profiles of housing construction and structural particular, lumber grading and sizes had become essentially uniform acrosswell the country.as standard Much construction of the standardization details. This indocument home building characteristics. To a limited degree, personal The front elevationBedrooms: and floor 2plan (66 of percent); a typical 3 home (33 percent) produced in 1950 is shownwas, inin theFigure opinion 2. of the author, one of the best may be attributed to the Federal Housing Administration (current day Department of Housing and Urban Development) with its interviews of home builders with experience dating The front elevation and floor plan of a typical home Bathrooms: 1-1/2 or less (96 percent) organized, instructive, and comprehensive building produced in 1900 is shown in Figure 1. Good examples as far back as 1917 were conducted to compare with Minimum Property Garage:Requirements 1 car (41 (MPRs) percent); wh ich0 (53 were percent) applied across the countrystandards following developed WWII, in the and United which States. were eventually information found in the literature. of traditional housing styles and architectural plans superceded2First floor by plan a firstis similar edition to size of and the shape Minimum of a small Property one-story Standardshome. (MPS) in 1958. At this point, the older “rules-of-thumb” were giving in the early 1900s are found in catalogues produced way to prescriptiveThe construction front elevation requirements and floor (e.g.,plan spanof a typical tables, homeconstruction specifications, etc.) that were based on practical as well The study focuses on structural aspects of housing by Sears, Roebuck and Co., a major producer of 3 produced in 1950 is shown in Figure 2. construction and breaks them into three periods of traditional American kit homes from about 1910 into as basic technical (engineering) criteria. Newer materials such as plywood sheathing were addressed as well as standard construction time: early 1900s, mid-1900s, and late 1900s. While the early 1930s (see Bibliography). Likewise, it should details. This document was, in the opinion of the author, one of the best organized, instructive, and comprehensive building standards it is recognized that change usually occurs slowly be recognized that a large portion of the public lived developed in the United States. and that practices vary regionally, an attempt is in rural areas that were not subject to municipal made to typify relevant housing construction data building codes, and housing needs were likely fulfilled and practices in each period. The following sections in a variety of ways that may not be well documented address: in the popular literature on housing construction. • General Housing Characteristics, For example, in Cotton Field’s No More it is stated • Design Loads, that “more than half of the farmers lived in one-and • Foundation Construction, two-room shacks that had not been whitewashed or • Wood-Frame Construction, and painted for many years, if ever. Many of these houses • Construction Quality. had holes in the roof, wall, and floor.” Further, U.S. Census data for 1900 reports that the value of land Additional information on thermal insulation and buildings per farm in eleven Southern states materials and methods are reported in Appendix A ranged from $600 to $2,000. By contrast, the values as a matter of special interest. for Indiana and Kansas were $6,550 and $3,718, respectively. Thus, living conditions and housing varied widely in the early 1900s. Figure 2. Profile home in 1950 (upper 1/2 story optional) Figure 2. Profile home in 1950 (upper 1/2 story optional). 92 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 93

4 1.3 LATE 1900S

The following characteristics describe a typical home and the housing market in 2000:

Population: 270 million (76 percent urban, 24 percent rural) Median family income: $45,000 New home price: $200,000 Type of purchase: 8 percent (many financing options) Ownership rate: 67 percent Total housing units: 107 million (approx. 50 percent single-family) Number of housing starts: 1.54 million (80 percent single-family) Average size (starts only): 2,000 sq. ft. or more Stories: One story (48 percent); 1-1/2 or 2 story (49 percent) Bedrooms: 2 or less (12 percent); 3 (54 percent); 4 or more (34 percent) Bathrooms: 1-1/2 or less (7 percent); 2 (40 percent); 2-1/2+ (53 percent) Garage: 2 car (65 percent)

The front elevation and floor plan of a typical home produced in 2000 is shown in Figure 3.

TABLE 2: AGE DISTRIBUTION OF EXISTING TABLE 3: GEOGRAPHIC DISTRIBUTION OF U.S. SINGLE-FAMILY HOMES (1995) U.S. SINGLE-FAMILY HOMES BY REGION (1995) Age of Home Percentage of Housing Stock Region Percentage of Housing Stock 76 years or older 9 Northeast 19 56 to 75 years old 11 Midwest 24 25 to 55 years old 35 South 37 0 to 24 years old 45 West 20

FigureFigure 3. Profile 3. Profile home in in 2000 2000 (2 story).(2 story). Stud Grade lumber; roof and floor framing lumber is 2.0 DESIGN LOADS typically No. 1 or No. 2 grade when dimension lumber is used. Fasteners are typically pneumatic-driven 0.113 In the early 20th century, structural loads for housing Bedrooms: 2 or less (12 percent); 3 (54 percent); 1.3 LATE 1900s to 0.131 inch diameter nails or staples. Most homes design were not well codified or standardized. Houses 4 or more (34 percent) The following characteristics describe a typical home are built following locally adopted and modified and members were largely designed using “rules of and the housing market in 2000: Bathrooms: 1-1/2 or less (7 percent); 2 (40 percent); national model building codes offered by one of three thumb” which implicitly considered member strength, 2-1/2+ (53 percent) 5 stiffness, and loading conditions. By 1923, the U.S. Population: 270 million (76 percent urban, private code development organizations. These codes Department of Commerce had formed a Building Code 24 percent rural) Garage: 2 car (65 percent) include the Uniform Building Code, National Building Code, and Standard Building Code, as well as the One- Committee that began to standardize design loads to Median family income: $45,000 The front elevation and floor plan of a typical home and Two-Family Dwelling Code (OTFDC) developed by be used specifically for homes. These loads were later produced in 2000 is shown in Figure 3. New home price: $200,000 CABO, an umbrella for the three national model code used to formulate various design recommendations Type of purchase: 8 percent By the late 1900s, detailed statistical data on new organizations. such as span tables, footing sizes, and other (many financing options) construction specifications. Recommended live and housing construction (such as collected by the U.S. It is interesting to note that while the cost of housing Ownership rate: 67 percent dead loads published in 1928 are shown in Table 4. Census and the NAHB Research Center’s Builder increased 100-fold or more during the 20th century, Total housing units: 107 million Practices Survey) had become readily available. family income increased by a factor of about 90. Thus, It is interesting to note that the relationship of live (approx. 50 percent single-family) Some basic housing construction statistics related the cost of a home in 1900 was about 3 times the load magnitude to influence area (tributary area) was Number of housing starts: 1.54 million to structural features of homes at this time are family income on average while the cost of a home in recognized by the U.S. Department of Commerce at (80 percent single-family) summarized in Table 1. 2000 was about 4 times the family income on average. this early time in a rudimentary fashion: Average size (starts only): 2,000 sq. ft. or more The species of framing lumber in the late 1900s Despite this apparent change, the increased availability “Although a live load of 40 pounds per square foot Stories: One story (48 percent); generally include Douglas Fir, Hem-Fir, Spruce-Pine- of private financing options for home purchasers has should be used in selecting all [individual] floor joists, 1-1/2 or 2 story (49 percent) Fir, and Southern Yellow Pine. Wall studs are typically contributed to a nearly 50 percent increase in the such a load will not occur over a large floor area at home ownership rate during the past century. the same time. The larger the area, the less chance TABLE 1: BASIC NEW HOUSING CONSTRUCTION STATISTICS IN LATE 1900s Also of significance is the distribution of age and there is of its being heavily loaded all over. In fact, geographic location of single-family homes in the the building Code Committee of the Department Foundation Type: Basement (34 percent); Crawlspace (11 percent); Slab (54 percent) United States, as shown in Tables 2 and 3. Similar data of Commerce, in 1923, after careful investigation, Floor Framing: Type: lumber, 62 percent; wood trusses, 9 percent; wood I-joists, 28 percent Size for the earlier part of the 20th century was not found. recommended that, in computing the load on girders of Lumber: 2x8, 8 percent; 2x10, 70 percent; 2x12, 21 percent (of lumber floors) carrying floors more than 200 square feet in area, a Species of Lumber: SYP 39 percent; DF 23 percent; other 37 percent live load of 30 pounds per square foot be used.” Floor Sheathing: 37 percent plywood; 30 percent OSB; 6 percent board Wall Framing: 73 percent 2x4@16”; 5 percent 2x4@24”; 17 percent 2x6@16”; 3 percent 2x6@24” TABLE 4: RECOMMENDED LIVE AND DEAD LOADS [U. S. Department of Commerce, 1928] Wall Sheathing: 11.2 percent plywood; 44.2 percent OSB; 24 percent foam panels; 20.6 percent other CONDITION POUNDS PER SQUARE FOOT Ceiling Height: 54 percent 8’ ceilings; 29 percent 9’ ceilings; 8 percent 10’ ceilings Live load, all floors used for living purposes 40 Wall Openings: 2.3 ext. doors; 1.2 patio doors; 14.5 windows; 1.2 fireplaces (13 to 15 percent of wall Live load for attic (used for light storage only) 20 area on average) Dead weight for average double floor and joists, but without plaster 10 Roof Sheathing: 27.6 percent plywood; 71 percent OSB Dead weight of plaster ceiling, including joists on light unfloored attics 10 Roof Framing: 6 percent rafters; 29 percent I-joist; 65 percent wood truss Roof of light construction, including both live and dead loads 10 Roof Pitch: 7 percent 4/12 or less; 63 percent 5/12 to 6/12; 30 percent 7/12 or greater Roof of medium construction with light slate or asbestos roofing, including 30 Roof Shape: 63 percent Gable; 36 percent Hip both live and dead loads Note: Percentages for floor, wall, and roof sheathing and framing are based on total aggregated floor and wall area for housing Roof of heavy construction with heavy slate or tile roofing, including both 40 starts. Other values are given as a percentage of the housing starts. live and dead loads

The following characteristics describe a typical home and the housing market in 2000:

The front elevation and floor plan of a typical home produced in 2000 is shown in Figure 3.

94 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 95 This practical consideration of influence area for 1900s rarely had separate spread footings; the first Typical presumptive (allowable, permissive, or safe) soil 4.0 WOOD-FRAME CONSTRUCTION dwelling design was subsequently lost in the develop- course of masonry was often laid directly on subgrade. bearing values during the 20th century are shown in ment of building codes later in the 20th century. Most The following relevant quote was found in Structural Table 5. It is noted that presumptive values decreased Prior to the 1900s some significant changes in basic modern codes do allow a floor live load of 30 psf to Analysis of Historic Buildings: drastically (became more conservative) in the later framing practices in the United Sates were set in be used for bedroom areas; however, this is a separate half of the 20th century with no compelling reason motion. Up through most of the 19th century, homes issue from that of influence area on design live loads. “Portland concrete and reinforced spread footings identified in the literature. were built following traditional timber construction began to appear at about the turn of the century. They known as braced framing adopted from England (see At the turn of the century, cities that had were obviously used sparingly at the beginning, as in By the mid-1900s and throughout the remainder of Figure 4). In this manner, homes used heavy squared comprehensive building laws generally specified the application of any new technology.” the century, the use of concrete footings and masonry timber frames and beams with diagonal bracing of 4x dwelling floor live loads ranging from 40 to 70 (block) or concrete walls had become common practice. or larger timbers. Wood joinery methods were used psf. Specified roof loads ranged from 25 to 50 When readily available, it is also found that many The introduction of separate spread footings is not well for heavy connections rather than steel fasteners. psf depending on the degree that dead, live, and homes before 1900 used stone masonry for foundation understood, as few documents used in this study spoke Intermediate framing members of smaller dimension snow loads were included in the values. Snow load walls or piers, with or without some type of mortar. directly to this issue. Perhaps, newer wall construction were used within the structural frame to provide for reductions based on simple relations to roof slope were Special consideration to foundations and soil support methods and materials allowed the use of thinner attachment of finish materials. sometimes recognized. Wind loads, where specified, was only given to very unique structures or soil foundation walls which brought about concern with ranged from 10 to 30 psf with 20 psf being most conditions. If engineered, building foundation bearing bearing area on the foundation soil. Perhaps a greater In the mid-1800s a new construction method, known as began to be used in the United common. However, wind loads did not find explicit pressures were usually designed with “appropriate dead concern or lower tolerance for settlement and cracking balloon framing, States. This method used repetitive light framing consideration in housing design until later in the and live loads” at the beginning of the 20th century. of foundation walls developed over time, as expectations for use of basements increased over the course of the members, generally 2x4s, made available by the 1900s, even though they were noted throughout the Even then, the techniques were quite arbitrary and century. Certainly, basement wall cracks are a major proliferation of sawmills. By the start of the 20th century. For most of the 20th century, it appears that relied heavily on experience and judgment of the wind loads, when considered, usually used a simple source of homeowner complaints or claims in modern century, balloon framing had practically replaced designer. Most building designs, at best, were based uniform load to be applied to vertical and horizontal homes; however, it does not appear that this was such the traditional heavy braced framing technique. The on a manual probing of the soil and reliance on local projected building surfaces. a concern earlier in the century. Data on modern balloon framing technique is illustrated in Figure 5. In practice and/or past performance of nearby building foundation construction types is reported in Table 1. some cases, vestiges of early practices such as the use of In addition, there appears to have been considerable foundations. 4x corner posts, beams, and sill framing variation in how loads were applied and analyzed. members existed well into the 20th For example, rafter selections were recommended by TABLE 5: PRESUMPTIVE SOIL BEARING VALUES century in combination with balloon using horizontal joist span tables produced in the BY TIME PERIOD framing. Balloon framing persisted 1930s. Thus, it is unclear as to how various loads were (pounds per square foot) until after World War II in some parts factored into the design of roofs until later in the 20th of the country. century when span tables specifically for rafter design EARLY 1900s considered roof live, dead, and snow loads explicitly. Variations in application of the balloon Soft/Wet Clay or Sand or Loam (2,000) In some cases the actual rafter sloped span was used framing method also recognized and wind loads were accounted. However, a lack of Firm Earth (2,500 to 3,500) trade-offs between economy and standard procedure for analyzing sloped rafters has Ordinary Clay/Sand Mix and Sand (4,000) performance. For example, Sears, Roebuck and Co., produced two types remained to this day. Hard Clay and Firm Course Sand (8,000) of pre-cut structural framing systems: By the mid-1900s, the National Bureau of Standards Firm Gravel/Sand Mix (12,000) one using the “honor-built” system and had produced a document titled Minimum Design Shale Rock (16,000) the other using the “standard-built” Loads in Buildings and Other Structures (ASA A58.1- Hard Rock (40,000) system. In advertising the “honor-built” 1955). In this document, the design floor live load for system, the following features were apartments and first floors of dwellings was set at 40 MID-1900s highlighted: psf; second floors and habitable attics at 30 psf; and Soft Clay (2,000) uninhabitable attics at 20 psf. ◆ Rafters, 2x6 or 2x4 inches (larger Firm Clay and Sand/Clay Mix (4,000) where needed), 14-3/8 inches apart Throughout the later half of the 1900s, building codes Fine dry sand (6,000) (16 inches on center). varied in the requirements for building design loads. ◆ Double plates over doors and However, by the end of the century, the major model Coarse Sand (8,000) windows (as headers and trim nailing building codes began to standardize load requirements Gravel (12,000) base). into a single format with uniform requirements, in Soft Rock (16,000) most cases based on the American Society of Civil ◆ Double studdings at sides of doors Engineer’s standard ASCE 7-98, Minimum Design Loads Hard Rock (80,000) and windows (as jamb support and trim nailing base). for Buildings and Other Structures (drawn from a later LATE-1900s edition of the National Bureau of Standards document ◆ Three studs at corners. Clay, Sandy Clay, Silty Clay, and clayey silt (1,000) ASA A58.1-55). ◆ High grade horizontal wood Sand, silty sand, clayey sand, silty gravel, and clayey sheathing boards, 13/16 inch thick gravel (1,500) with tarred felt overlay between 3.0 FOUNDATION CONSTRUCTION Sandy gravel and/or gravel (2,000) sheathing and wood siding. Foundation construction at the beginning of the Sedimentary and foliated rock (2,000) ◆ Double floors with heavy building 1900s differed significantly from that used by the end Massive crystalline bedrock (4,000) paper between the subfloor and of the century. Residential foundations in the early Figure 4. Braced Framing pre-1900. finished floor. Figure 4. Braced Framing pre-1900. Figure 5. Balloon Framing Technique in Early 1900s. 96 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 97

11 This practical consideration of influence area for 1900s rarely had separate spread footings; the first Typical presumptive (allowable, permissive, or safe) soil 4.0 WOOD-FRAME CONSTRUCTION dwelling design was subsequently lost in the develop- course of masonry was often laid directly on subgrade. bearing values during the 20th century are shown in ment of building codes later in the 20th century. Most The following relevant quote was found in Structural Table 5. It is noted that presumptive values decreased Prior to the 1900s some significant changes in basic modern codes do allow a floor live load of 30 psf to Analysis of Historic Buildings: drastically (became more conservative) in the later framing practices in the United Sates were set in be used for bedroom areas; however, this is a separate half of the 20th century with no compelling reason motion. Up through most of the 19th century, homes issue from that of influence area on design live loads. “Portland concrete and reinforced spread footings identified in the literature. were built following traditional timber construction began to appear at about the turn of the century. They known as braced framing adopted from England (see At the turn of the century, cities that had were obviously used sparingly at the beginning, as in By the mid-1900s and throughout the remainder of Figure 4). In this manner, homes used heavy squared comprehensive building laws generally specified the application of any new technology.” the century, the use of concrete footings and masonry timber frames and beams with diagonal bracing of 4x dwelling floor live loads ranging from 40 to 70 (block) or concrete walls had become common practice. or larger timbers. Wood joinery methods were used psf. Specified roof loads ranged from 25 to 50 When readily available, it is also found that many The introduction of separate spread footings is not well for heavy connections rather than steel fasteners. psf depending on the degree that dead, live, and homes before 1900 used stone masonry for foundation understood, as few documents used in this study spoke Intermediate framing members of smaller dimension snow loads were included in the values. Snow load walls or piers, with or without some type of mortar. directly to this issue. Perhaps, newer wall construction were used within the structural frame to provide for reductions based on simple relations to roof slope were Special consideration to foundations and soil support methods and materials allowed the use of thinner attachment of finish materials. sometimes recognized. Wind loads, where specified, was only given to very unique structures or soil foundation walls which brought about concern with ranged from 10 to 30 psf with 20 psf being most conditions. If engineered, building foundation bearing bearing area on the foundation soil. Perhaps a greater In the mid-1800s a new construction method, known as began to be used in the United common. However, wind loads did not find explicit pressures were usually designed with “appropriate dead concern or lower tolerance for settlement and cracking balloon framing, States. This method used repetitive light framing consideration in housing design until later in the and live loads” at the beginning of the 20th century. of foundation walls developed over time, as expectations for use of basements increased over the course of the members, generally 2x4s, made available by the 1900s, even though they were noted throughout the Even then, the techniques were quite arbitrary and century. Certainly, basement wall cracks are a major proliferation of sawmills. By the start of the 20th century. For most of the 20th century, it appears that relied heavily on experience and judgment of the wind loads, when considered, usually used a simple source of homeowner complaints or claims in modern century, balloon framing had practically replaced designer. Most building designs, at best, were based uniform load to be applied to vertical and horizontal homes; however, it does not appear that this was such the traditional heavy braced framing technique. The on a manual probing of the soil and reliance on local projected building surfaces. a concern earlier in the century. Data on modern balloon framing technique is illustrated in Figure 5. In practice and/or past performance of nearby building foundation construction types is reported in Table 1. some cases, vestiges of early practices such as the use of In addition, there appears to have been considerable foundations. 4x corner posts, beams, and sill framing variation in how loads were applied and analyzed. members existed well into the 20th For example, rafter selections were recommended by TABLE 5: PRESUMPTIVE SOIL BEARING VALUES century in combination with balloon using horizontal joist span tables produced in the BY TIME PERIOD framing. Balloon framing persisted 1930s. Thus, it is unclear as to how various loads were (pounds per square foot) until after World War II in some parts factored into the design of roofs until later in the 20th of the country. century when span tables specifically for rafter design EARLY 1900s considered roof live, dead, and snow loads explicitly. Variations in application of the balloon Soft/Wet Clay or Sand or Loam (2,000) In some cases the actual rafter sloped span was used framing method also recognized and wind loads were accounted. However, a lack of Firm Earth (2,500 to 3,500) trade-offs between economy and standard procedure for analyzing sloped rafters has Ordinary Clay/Sand Mix and Sand (4,000) performance. For example, Sears, Roebuck and Co., produced two types remained to this day. Hard Clay and Firm Course Sand (8,000) of pre-cut structural framing systems: By the mid-1900s, the National Bureau of Standards Firm Gravel/Sand Mix (12,000) one using the “honor-built” system and had produced a document titled Minimum Design Shale Rock (16,000) the other using the “standard-built” Loads in Buildings and Other Structures (ASA A58.1- Hard Rock (40,000) system. In advertising the “honor-built” 1955). In this document, the design floor live load for system, the following features were apartments and first floors of dwellings was set at 40 MID-1900s highlighted: psf; second floors and habitable attics at 30 psf; and Soft Clay (2,000) uninhabitable attics at 20 psf. ◆ Rafters, 2x6 or 2x4 inches (larger Firm Clay and Sand/Clay Mix (4,000) where needed), 14-3/8 inches apart Throughout the later half of the 1900s, building codes Fine dry sand (6,000) (16 inches on center). varied in the requirements for building design loads. ◆ Double plates over doors and However, by the end of the century, the major model Coarse Sand (8,000) windows (as headers and trim nailing building codes began to standardize load requirements Gravel (12,000) base). into a single format with uniform requirements, in Soft Rock (16,000) most cases based on the American Society of Civil ◆ Double studdings at sides of doors Engineer’s standard ASCE 7-98, Minimum Design Loads Hard Rock (80,000) and windows (as jamb support and trim nailing base). for Buildings and Other Structures (drawn from a later LATE-1900s edition of the National Bureau of Standards document ◆ Three studs at corners. Clay, Sandy Clay, Silty Clay, and clayey silt (1,000) ASA A58.1-55). ◆ High grade horizontal wood Sand, silty sand, clayey sand, silty gravel, and clayey sheathing boards, 13/16 inch thick gravel (1,500) with tarred felt overlay between 3.0 FOUNDATION CONSTRUCTION Sandy gravel and/or gravel (2,000) sheathing and wood siding. Foundation construction at the beginning of the Sedimentary and foliated rock (2,000) ◆ Double floors with heavy building 1900s differed significantly from that used by the end Massive crystalline bedrock (4,000) paper between the subfloor and of the century. Residential foundations in the early Figure 4. Braced Framing pre-1900. finished floor. Figure 4. Braced Framing pre-1900. Figure 5. Balloon Framing Technique in Early 1900s. 96 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 97

11 following are key specifications of Sears’ For example, balloon framing required th “standard-built” homes: the use of long wall framing members Throughout the 20 century, 16 inch on center framing has (studs) which were more expensive remained the dominant choice. Interestingly, this practice has ◆ Rafters, 2x4 inches, 22-3/8 inches and less available. Also, balloon apart (24 inches on center); 2x4 been associated with an early concern to provide adequate support framing required fire blocking between ceiling joists at 16 inches on center for finish materials (i.e., exterior wood siding or sheathing and, wall framing at story levels to comply (for interior finish). particularly, interior lath and plaster finishes). On the other hand, with modern building codes (initiated ◆ Single plates over doors and windows in the 1920s). In contrast, platform spacing of roof framing members has largely increased from 16 (no headers or trim nailing base). framing is inherently fire blocked by inch on center (early to mid-1900s) to 24 inches on center in the ◆ Single studdings at sides of doors and the use of horizontal wall plates at late 1900s. This change is associated with the inception and later windows. the top and bottom of each story. In dominance of wood roof trusses in the second half of the 20th ◆ Two studs at corners. addition, the balloon frame approach was essentially limited to “regular” Century. However, 16 inch on center roof framing still finds ◆ No wood sheathing (only exterior two-story construction and did not limited use today, particularly in complicated roof designs that wood siding of 1x6). readily allow for newer housing styles necessitate rafter framing. ◆ No sub-floor (finish flooring applied that featured story offsets (i.e., floor direct to joists). overhangs) and other “irregularities” It should be noted that 24 inch on center wall framing has been ◆ Tarred felt under floors and siding. in design. Finally, the platform th framing technique provides a solid used throughout the 20 century in at least a small portion of ◆ 2x8 inch joists placed 22-3/8 inches housing construction for reasons of economy and, more recently, apart (24 inches on center), spans and safe work platform from which to generally not exceeding 12 feet. stage construction for upper stories. for its additional benefits of improved energy efficiency and Platform framing has dominated the resource conservation. Changes to panel forms of exterior and ◆ Studdings, 2x4 inches, 14-3/8 inches housing market since the mid-1900s interior sheathing materials (including the use of plywood and apart (16 inches on center), double with a few refinements as follows: plate at top and single at bottom of OSB sheathing panels and gypsum wallboard, as opposed to wall; ceiling heights typically 8 feet-3 ◆ unnecessary use of bridging between boards or lath and plaster) have perhaps contributed to a greater inches. studs and floor joists was eliminated; use of 24 inch on center framing today than in the early 20th ◆ Framing lumber for walls, floors, and ◆ panel products have replaced the century. Still, 24 inch on center framing is generally used in less roofs uses No. 1 Douglas Fir or Pacific use of boards for wall, floor, and roof than 10 percent of wall area in modern residential construction Coast Hemlock (non-Sears standard sheathing; construction is noted to use lower ◆ wall sheathing no longer laps over annually. quality or No. 2 and No. 3 lumber the floor perimeter (except in some and species such as Tamarak or White isolated high wind locales); and Floor construction has also seen some use of alternate spacings Pine). ◆ foundation sill members are such as 19.2 inch and 24 inch. In recent years, increased use of Figure 5. Balloon Framing Technique in Early 1900s. ◆ Common wire nails of sufficient anchored to the foundation. Figure 6. Platform Framing. wider spacing for floor framing members may be associated with quantity and variety of sizes. Figure 6. Platform Framing. Figure 4. Braced Framing pre-1900. Figure 5. Balloon Framing Technique in Early 1900s. Throughout the 20th century, 16 inch Note: Platform framing in Figure 6 is representative of early platform framing. increased use of engineered wood products such as parallel chord ◆ 2x8 inch joists, or 2x10 where needed, 14-3/8 inches ◆ Cypress exterior trim. on center framing has remained the PlatformNote: Platform framing framing in the in Figuremid-to 6 late-1900sis representative used of panel early products platform framing.in lieu of Platf boardorm wood trusses and wood I-joists. apart (16 inches on center). ◆ dominant choice. Interestingly, this sheathingframing in theand mid bridging- to late in-1900s floors used and panel walls products was ineliminated. lieu of board sheathing and bridging All outside paint, two coats. in floors and walls was eliminated. practice has been associated with an ◆ Studdings, 2x4 inches, 14-3/8 inches apart (16 inches Sears also advertised cottage style or portable homes on center), double plate at top and single at bottom early concern to provide adequate with 2x2 No. 1 yellow pine wall framing, 2x3 roof wallboard, as opposed to boards or lath and plaster) of wall, ceiling height of typically 8 feet-2 inches to support for finish materials (i.e., exterior wood siding rafters, and post foundations. The largest size had or sheathing and, particularly, interior lath and plaster have perhaps contributed to a greater use of 24 inch on 9 feet for above grade stories and as low as 7 feet for 11 three rooms with overall plan dimensions of 20 feet finishes). On the other hand, spacing of roof14 framing center framing today than in the early 20th century. basements. by 16 feet, plus a 5 foot covered porch. Sears noted members has largely increased from 16 inch on center Still, 24 inch on center framing is generally used in ◆ High quality framing lumber (virgin growth, dense that their “standard-built” homes incorporated some (early to mid-1900s) to 24 inches on center in the late less than 10 percent of wall area in modern residential grain, from the Pacific Northwest, Douglas-Fir and improvements over the common practice of that time, 1900s. This change is associated with the inception and construction annually. Hemlock) specially sorted, stored, and dried at Sears such as the use of three-stud corners and doubled 2x4 later dominance of wood roof trusses in the second Floor construction has also seen some use of alternate lumber yards. members at window and door openings for improved half of the 20th Century. However, 16 inch on center spacings such as 19.2 inch and 24 inch. In recent ◆ Common wire nails of sufficient quantity and finish attachment. It is unknown how many homes of roof framing still finds limited use today, particularly years, increased use of wider spacing for floor framing variety of sizes. each type were sold by Sears, Roebuck and Co. But, the in complicated roof designs that necessitate rafter catalogues give clear evidence that at least two to three members may be associated with increased use of ◆ framing. Genuine cypress window and door casings (exterior distinctly different levels of dwelling construction were engineered wood products such as parallel chord wood It should be noted that 24 inch on center wall framing trim), 1-1/8 inches thick, naturally weather resistant. recognized in the early 1900s as a matter of economy trusses and wood I-joists. has been used throughout the 20th century in at least ◆ 3 coats of guaranteed paint on outside. verses quality. a small portion of housing construction for reasons The “standard-built” construction was advertised (at By the mid-1900s and during the housing “boom” of economy and, more recently, for its additional the back of the 1928 Sears catalogue) as the “most following WWII, the preferred framing practice had benefits of improved energy efficiency and resource house per dollar invested” for smaller homes of 1 evolved to platform framing, a further refinement of conservation. Changes to panel forms of exterior to 1-1/2 stories. The largest home of this type had balloon framing. Platform framing is shown in Figure and interior sheathing materials (including the use four rooms within a 24 feet by 36 feet plan. The 6. This change was driven by economy and practicality. of plywood and OSB sheathing panels and gypsum

98 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 99 following are key specifications of Sears’ For example, balloon framing required th “standard-built” homes: the use of long wall framing members Throughout the 20 century, 16 inch on center framing has (studs) which were more expensive remained the dominant choice. Interestingly, this practice has ◆ Rafters, 2x4 inches, 22-3/8 inches and less available. Also, balloon apart (24 inches on center); 2x4 been associated with an early concern to provide adequate support framing required fire blocking between ceiling joists at 16 inches on center for finish materials (i.e., exterior wood siding or sheathing and, wall framing at story levels to comply (for interior finish). particularly, interior lath and plaster finishes). On the other hand, with modern building codes (initiated ◆ Single plates over doors and windows in the 1920s). In contrast, platform spacing of roof framing members has largely increased from 16 (no headers or trim nailing base). framing is inherently fire blocked by inch on center (early to mid-1900s) to 24 inches on center in the ◆ Single studdings at sides of doors and the use of horizontal wall plates at late 1900s. This change is associated with the inception and later windows. the top and bottom of each story. In dominance of wood roof trusses in the second half of the 20th ◆ Two studs at corners. addition, the balloon frame approach was essentially limited to “regular” Century. However, 16 inch on center roof framing still finds ◆ No wood sheathing (only exterior two-story construction and did not limited use today, particularly in complicated roof designs that wood siding of 1x6). readily allow for newer housing styles necessitate rafter framing. ◆ No sub-floor (finish flooring applied that featured story offsets (i.e., floor direct to joists). overhangs) and other “irregularities” It should be noted that 24 inch on center wall framing has been ◆ Tarred felt under floors and siding. in design. Finally, the platform th framing technique provides a solid used throughout the 20 century in at least a small portion of ◆ 2x8 inch joists placed 22-3/8 inches housing construction for reasons of economy and, more recently, apart (24 inches on center), spans and safe work platform from which to generally not exceeding 12 feet. stage construction for upper stories. for its additional benefits of improved energy efficiency and Platform framing has dominated the resource conservation. Changes to panel forms of exterior and ◆ Studdings, 2x4 inches, 14-3/8 inches housing market since the mid-1900s interior sheathing materials (including the use of plywood and apart (16 inches on center), double with a few refinements as follows: plate at top and single at bottom of OSB sheathing panels and gypsum wallboard, as opposed to wall; ceiling heights typically 8 feet-3 ◆ unnecessary use of bridging between boards or lath and plaster) have perhaps contributed to a greater inches. studs and floor joists was eliminated; use of 24 inch on center framing today than in the early 20th ◆ Framing lumber for walls, floors, and ◆ panel products have replaced the century. Still, 24 inch on center framing is generally used in less roofs uses No. 1 Douglas Fir or Pacific use of boards for wall, floor, and roof than 10 percent of wall area in modern residential construction Coast Hemlock (non-Sears standard sheathing; construction is noted to use lower ◆ wall sheathing no longer laps over annually. quality or No. 2 and No. 3 lumber the floor perimeter (except in some and species such as Tamarak or White isolated high wind locales); and Floor construction has also seen some use of alternate spacings Pine). ◆ foundation sill members are such as 19.2 inch and 24 inch. In recent years, increased use of Figure 5. Balloon Framing Technique in Early 1900s. ◆ Common wire nails of sufficient anchored to the foundation. Figure 6. Platform Framing. wider spacing for floor framing members may be associated with quantity and variety of sizes. Figure 6. Platform Framing. Figure 4. Braced Framing pre-1900. Figure 5. Balloon Framing Technique in Early 1900s. Throughout the 20th century, 16 inch Note: Platform framing in Figure 6 is representative of early platform framing. increased use of engineered wood products such as parallel chord ◆ 2x8 inch joists, or 2x10 where needed, 14-3/8 inches ◆ Cypress exterior trim. on center framing has remained the PlatformNote: Platform framing framing in the in Figuremid-to 6 late-1900sis representative used of panel early products platform framing.in lieu of Platf boardorm wood trusses and wood I-joists. apart (16 inches on center). ◆ dominant choice. Interestingly, this sheathingframing in theand mid bridging- to late in-1900s floors used and panel walls products was ineliminated. lieu of board sheathing and bridging All outside paint, two coats. in floors and walls was eliminated. practice has been associated with an ◆ Studdings, 2x4 inches, 14-3/8 inches apart (16 inches Sears also advertised cottage style or portable homes on center), double plate at top and single at bottom early concern to provide adequate with 2x2 No. 1 yellow pine wall framing, 2x3 roof wallboard, as opposed to boards or lath and plaster) of wall, ceiling height of typically 8 feet-2 inches to support for finish materials (i.e., exterior wood siding rafters, and post foundations. The largest size had or sheathing and, particularly, interior lath and plaster have perhaps contributed to a greater use of 24 inch on 9 feet for above grade stories and as low as 7 feet for 11 three rooms with overall plan dimensions of 20 feet finishes). On the other hand, spacing of roof14 framing center framing today than in the early 20th century. basements. by 16 feet, plus a 5 foot covered porch. Sears noted members has largely increased from 16 inch on center Still, 24 inch on center framing is generally used in ◆ High quality framing lumber (virgin growth, dense that their “standard-built” homes incorporated some (early to mid-1900s) to 24 inches on center in the late less than 10 percent of wall area in modern residential grain, from the Pacific Northwest, Douglas-Fir and improvements over the common practice of that time, 1900s. This change is associated with the inception and construction annually. Hemlock) specially sorted, stored, and dried at Sears such as the use of three-stud corners and doubled 2x4 later dominance of wood roof trusses in the second Floor construction has also seen some use of alternate lumber yards. members at window and door openings for improved half of the 20th Century. However, 16 inch on center spacings such as 19.2 inch and 24 inch. In recent ◆ Common wire nails of sufficient quantity and finish attachment. It is unknown how many homes of roof framing still finds limited use today, particularly years, increased use of wider spacing for floor framing variety of sizes. each type were sold by Sears, Roebuck and Co. But, the in complicated roof designs that necessitate rafter catalogues give clear evidence that at least two to three members may be associated with increased use of ◆ framing. Genuine cypress window and door casings (exterior distinctly different levels of dwelling construction were engineered wood products such as parallel chord wood It should be noted that 24 inch on center wall framing trim), 1-1/8 inches thick, naturally weather resistant. recognized in the early 1900s as a matter of economy trusses and wood I-joists. has been used throughout the 20th century in at least ◆ 3 coats of guaranteed paint on outside. verses quality. a small portion of housing construction for reasons The “standard-built” construction was advertised (at By the mid-1900s and during the housing “boom” of economy and, more recently, for its additional the back of the 1928 Sears catalogue) as the “most following WWII, the preferred framing practice had benefits of improved energy efficiency and resource house per dollar invested” for smaller homes of 1 evolved to platform framing, a further refinement of conservation. Changes to panel forms of exterior to 1-1/2 stories. The largest home of this type had balloon framing. Platform framing is shown in Figure and interior sheathing materials (including the use four rooms within a 24 feet by 36 feet plan. The 6. This change was driven by economy and practicality. of plywood and OSB sheathing panels and gypsum

98 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 99 analysis of special structures (i.e., railroad trestles) 4.1 WOOD MATERIALS 1 TABLE 6 TYPICAL FRAMING LUMBER SPECIES BY TIME PERIOD TABLE 7 TYPICAL LUMBER GRADES BY TIME PERIOD based on evaluation of stresses on individual EARLY 1900S LATE 1900S EARLY 1900s * MID-1900s ** LATE 1900s ** members using quantified structural properties 4.1.1 Size of various wood species. By the 1920s, allowable Red Cypress*# Douglas Fir No. 1 Select Structural Select Structural stresses for various species and two grades Significant changes to sizes of Redwood*# Hem-Fir No. 2 No 1 Dense No 1 Dense dimension lumber used in balloon (No.1 and No.2) of structural timbers had been Douglas Fir-coastal# Southern Yellow Pine No. 3 No 1 No1 published (see Table 9). Later in the 1920s and framing occurred in the early 1900s. At Douglas Fir – inland*# Spruce-Pine-Fir Culls No 2 Dense No 2 Dense 1930s, allowable stresses for structural lumber and first, members where often rough sawn Pacific Coast Hemlock# Southern Pine No 2 No 2 timber for dry uses had been published (see Table (or perhaps only surfaced on two sides) Western Larch*# Dense Construction Stud 10). The following quotation from Light Frame and available in actual (approximate) Eastern Hemlock*# Construction Construction House Construction describes the use of the data 2 inch thickness and depths of 4, 6, Eastern Spruce*# Standard Standard in Table 10 in the 1930s: 8, 10, 12, and even 14 inches. Later, California White Pine# Utility ostensibly to account for surfacing White Pine (Northern, Idaho, and sugar)# “In Table [10] is given a list of various ** Audel’s describes No 1 as “practically perfect” and No 2 and shrinkage, finished lumber sizes Norway Pine# softwoods used for building construction, as allowing two sound knots, 1” of sap, and one other were reduced to 1-3/4 inch thickness with allowable unit working stresses for each Port Orford Cedar# blemish. In Light Frame House Construction, No. 2 is with actual depths of 1/4 inch scant species and grade. The species in the upper White Fir*# noted as OK for economical or temporary construction. of nominal for members up to 4-inch Tamarack*# half of the list are manufactured in structural ** Grade class designations vary by grading agency and depth and 1/2-inch scant for members Long leaf Southern Pine# grades as shown. Definite working stresses lumber species groupings based on 1962 and 1997 over 4-inch depth. Still later, the Short Leaf Southern Pine# have been assigned to all these grades by the industry design specifications. thickness was reduced to 1-5/8 inch North Carolina Pine# manufacturers. For the species in the lower (as in the Sears homes of 1928) and Arkansas Soft Pine# half of the table, structural grades are seldom the depth was reduced to 3-5/8, Southern Yellow Pine# literature prior to 1900. However, because of the manufactured as such. Nevertheless, timbers limited tests conducted, the experimenters often from these species, if carefully selected as to 5-5/8, 7-1/2, 9-1/2, etc. Finally, in the 1 mid-1900s, lumber dimensions were Audel’s mentions White Pine as the most common framing lumber on the reported different structural property values and used influence of defects, may be rated as ‘select East Coast in the early 1900s, which is also confirmed by similar references reduced to the standard sizes that different terminology in describing results. One of structural,’ and timbers of lower grade as in the Sears catalogues. are in use today. The nominal size the better examples of wood engineering data was ‘common structural.’ The working stresses vs. actual size in current use are as * Species reported as being appropriate for studs (No. 1 or No. 2 grade produced in 1913 by Carnegie Steel (Table 8) who used shown may then be applied.” follows: 2x4 (1.5 in by 3.5 in), 2x6 (1.5 recommended) timber for the purpose of railroad trestle design. While It is apparent that the application of grading standards in by 5.5 inch), 2x8 (1.5 in by 7.25 in), # Species reported as being appropriate for joists and girders (No. 1 grade a larger safety margin of about 5 was used for railroad was in its infancy in the 1930s. The common lumber 2x10 (1.5 in by 9.25 in), and 2x12 (1.5 recommended) design, a safety factor of 4 was typically recommended grades (No. 1 and No. 2) were loosely defined in practice in by 11.25 in). for general use where engineering was applied. The and may have varied substantially at the local level of structural quality are the grading methods used for safety factors were typically applied to average ultimate supply. While published bending properties varied by 4.1.2 Type/Species lumber. However, density is perhaps the single most strength values from limited testing to develop grade and species, they did not differ much according to important parameter to consider, as it can be correlated allowable or working stress design values. size of member. Similarly, modulus of elasticity values Over the 20th century, supply and demand has to several structural properties including bending As discussed later, many wood members for light tended to vary by species, but not by grade. dictated numerous changes in forestry and availability strength and connection capacity. Grading methods building construction were probably sized or designed of wood materials in the United States. At the have evolved a great deal over the past century. Early tests of lumber density are not readily found by intuitive “rules of thumb” passed down through beginning of the 20th century, virgin growth lumber Typical grades in each time period are shown in Table in the available literature. Because of the lack of years of experience. For example, there were no records (also known as old growth) was commonly used. As 7 below. As shown, the grade categories of lumber grading standards at that time, the lack of standard found of engineering calculations or test data in the resources of virgin growth lumber diminished, first in have increased with time. Modern home construction terminology, and the frequent use of locally grown origins of balloon framing techniques in the mid-to the east and then in the west, use of managed forests generally uses two or three grades of dimension lumber and milled timber, it is difficult to determine the range late-1800s. However, this outcome is not to suggest became more common and practically essential by and three to four different species or species groups. of lumber densities typifying residential and other the mid-to late-1900s. Wood species typically used for that no structural consideration or verification testing building construction earlier in the 1900s. However, in framing lumber in residential construction are shown By the 1930s, lumber stress values for various species was performed, since “proof testing” has historically 1885 the data in Table 11 was reported. in Table 6 by time period. As seen in the early 1900s and grades had been used to develop prescriptive span been a common practice to validate new construction tables for dwelling construction. No. 2 grade lumber techniques. For example, modern roof trusses were By the 1930s, stress values for many popular wood many local species were used. However, Sears boasted species, and typically two grades each, were available in being able to ship the best available Douglas Fir and was typically recommended for studs while No.1 grade developed using engineering tests and data in the was recommended for joist and rafter framing. The use mid-1900s. Proof testing of actual truss constructions from lumber grading agencies that followed grading Pacific Coast Hemlock for their framing lumber. By the standards. Through the mid-to late-1900s structural late 1900s, wood species were organized into 'species of No. 2 grade lumber for joists was recognized as a (i.e., stacking weights on a trussed roof) was often “more economical construction.” But, a 2 inch deeper done to verify performance to a skeptical audience. In data on a wide variety of wood species grew rapidly. groups' each including several species with similar By the second half of the 20th century, grading rules properties. member was recommended for use with span tables essence, the concept of “seeing is believing” has played based on No. 1 grade lumber. However, in the 1960s, a significant role in the adoption of new construction and agencies were in full swing, and numerous design many builders reported using construction grade technologies. values were published in wood industry specifications such as the 4.1.3 Structural Properties lumber for floor joists. National Design Specification for Wood In summary, it appears that two methods of wood Construction and its supplement of wood design values. For the purpose of this paper, structural quality deals Evidently, little analytical concern was placed on construction verification were emerging in the United While dimension lumber dominated the housing with characteristics that affect the strength of lumber, structural capacity prior to the 1900s except by way States in the late 1800s and early 1900s. The first relied market through most of the 20th century, the late not factors such as straightness (although there may of practical experience, although limited discussions on experience with constructed systems for specific 1990s saw a dramatic increase in the use of engineered be relevant correlation between tendency to warp and test data related to structural properties of some applications (i.e., balloon framing of buildings). The wood members such as trusses, wood I-joists, and and structural properties). The primary measures of commonly used wood species may be found in the second and newer method relied on engineering engineered wood panel products (see Table 1).

100 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 101 analysis of special structures (i.e., railroad trestles) 4.1 WOOD MATERIALS 1 TABLE 6 TYPICAL FRAMING LUMBER SPECIES BY TIME PERIOD TABLE 7 TYPICAL LUMBER GRADES BY TIME PERIOD based on evaluation of stresses on individual EARLY 1900S LATE 1900S EARLY 1900s * MID-1900s ** LATE 1900s ** members using quantified structural properties 4.1.1 Size of various wood species. By the 1920s, allowable Red Cypress*# Douglas Fir No. 1 Select Structural Select Structural stresses for various species and two grades Significant changes to sizes of Redwood*# Hem-Fir No. 2 No 1 Dense No 1 Dense dimension lumber used in balloon (No.1 and No.2) of structural timbers had been Douglas Fir-coastal# Southern Yellow Pine No. 3 No 1 No1 published (see Table 9). Later in the 1920s and framing occurred in the early 1900s. At Douglas Fir – inland*# Spruce-Pine-Fir Culls No 2 Dense No 2 Dense 1930s, allowable stresses for structural lumber and first, members where often rough sawn Pacific Coast Hemlock# Southern Pine No 2 No 2 timber for dry uses had been published (see Table (or perhaps only surfaced on two sides) Western Larch*# Dense Construction Stud 10). The following quotation from Light Frame and available in actual (approximate) Eastern Hemlock*# Construction Construction House Construction describes the use of the data 2 inch thickness and depths of 4, 6, Eastern Spruce*# Standard Standard in Table 10 in the 1930s: 8, 10, 12, and even 14 inches. Later, California White Pine# Utility ostensibly to account for surfacing White Pine (Northern, Idaho, and sugar)# “In Table [10] is given a list of various ** Audel’s describes No 1 as “practically perfect” and No 2 and shrinkage, finished lumber sizes Norway Pine# softwoods used for building construction, as allowing two sound knots, 1” of sap, and one other were reduced to 1-3/4 inch thickness with allowable unit working stresses for each Port Orford Cedar# blemish. In Light Frame House Construction, No. 2 is with actual depths of 1/4 inch scant species and grade. The species in the upper White Fir*# noted as OK for economical or temporary construction. of nominal for members up to 4-inch Tamarack*# half of the list are manufactured in structural ** Grade class designations vary by grading agency and depth and 1/2-inch scant for members Long leaf Southern Pine# grades as shown. Definite working stresses lumber species groupings based on 1962 and 1997 over 4-inch depth. Still later, the Short Leaf Southern Pine# have been assigned to all these grades by the industry design specifications. thickness was reduced to 1-5/8 inch North Carolina Pine# manufacturers. For the species in the lower (as in the Sears homes of 1928) and Arkansas Soft Pine# half of the table, structural grades are seldom the depth was reduced to 3-5/8, Southern Yellow Pine# literature prior to 1900. However, because of the manufactured as such. Nevertheless, timbers limited tests conducted, the experimenters often from these species, if carefully selected as to 5-5/8, 7-1/2, 9-1/2, etc. Finally, in the 1 mid-1900s, lumber dimensions were Audel’s mentions White Pine as the most common framing lumber on the reported different structural property values and used influence of defects, may be rated as ‘select East Coast in the early 1900s, which is also confirmed by similar references reduced to the standard sizes that different terminology in describing results. One of structural,’ and timbers of lower grade as in the Sears catalogues. are in use today. The nominal size the better examples of wood engineering data was ‘common structural.’ The working stresses vs. actual size in current use are as * Species reported as being appropriate for studs (No. 1 or No. 2 grade produced in 1913 by Carnegie Steel (Table 8) who used shown may then be applied.” follows: 2x4 (1.5 in by 3.5 in), 2x6 (1.5 recommended) timber for the purpose of railroad trestle design. While It is apparent that the application of grading standards in by 5.5 inch), 2x8 (1.5 in by 7.25 in), # Species reported as being appropriate for joists and girders (No. 1 grade a larger safety margin of about 5 was used for railroad was in its infancy in the 1930s. The common lumber 2x10 (1.5 in by 9.25 in), and 2x12 (1.5 recommended) design, a safety factor of 4 was typically recommended grades (No. 1 and No. 2) were loosely defined in practice in by 11.25 in). for general use where engineering was applied. The and may have varied substantially at the local level of structural quality are the grading methods used for safety factors were typically applied to average ultimate supply. While published bending properties varied by 4.1.2 Type/Species lumber. However, density is perhaps the single most strength values from limited testing to develop grade and species, they did not differ much according to important parameter to consider, as it can be correlated allowable or working stress design values. size of member. Similarly, modulus of elasticity values Over the 20th century, supply and demand has to several structural properties including bending As discussed later, many wood members for light tended to vary by species, but not by grade. dictated numerous changes in forestry and availability strength and connection capacity. Grading methods building construction were probably sized or designed of wood materials in the United States. At the have evolved a great deal over the past century. Early tests of lumber density are not readily found by intuitive “rules of thumb” passed down through beginning of the 20th century, virgin growth lumber Typical grades in each time period are shown in Table in the available literature. Because of the lack of years of experience. For example, there were no records (also known as old growth) was commonly used. As 7 below. As shown, the grade categories of lumber grading standards at that time, the lack of standard found of engineering calculations or test data in the resources of virgin growth lumber diminished, first in have increased with time. Modern home construction terminology, and the frequent use of locally grown origins of balloon framing techniques in the mid-to the east and then in the west, use of managed forests generally uses two or three grades of dimension lumber and milled timber, it is difficult to determine the range late-1800s. However, this outcome is not to suggest became more common and practically essential by and three to four different species or species groups. of lumber densities typifying residential and other the mid-to late-1900s. Wood species typically used for that no structural consideration or verification testing building construction earlier in the 1900s. However, in framing lumber in residential construction are shown By the 1930s, lumber stress values for various species was performed, since “proof testing” has historically 1885 the data in Table 11 was reported. in Table 6 by time period. As seen in the early 1900s and grades had been used to develop prescriptive span been a common practice to validate new construction tables for dwelling construction. No. 2 grade lumber techniques. For example, modern roof trusses were By the 1930s, stress values for many popular wood many local species were used. However, Sears boasted species, and typically two grades each, were available in being able to ship the best available Douglas Fir and was typically recommended for studs while No.1 grade developed using engineering tests and data in the was recommended for joist and rafter framing. The use mid-1900s. Proof testing of actual truss constructions from lumber grading agencies that followed grading Pacific Coast Hemlock for their framing lumber. By the standards. Through the mid-to late-1900s structural late 1900s, wood species were organized into 'species of No. 2 grade lumber for joists was recognized as a (i.e., stacking weights on a trussed roof) was often “more economical construction.” But, a 2 inch deeper done to verify performance to a skeptical audience. In data on a wide variety of wood species grew rapidly. groups' each including several species with similar By the second half of the 20th century, grading rules properties. member was recommended for use with span tables essence, the concept of “seeing is believing” has played based on No. 1 grade lumber. However, in the 1960s, a significant role in the adoption of new construction and agencies were in full swing, and numerous design many builders reported using construction grade technologies. values were published in wood industry specifications such as the 4.1.3 Structural Properties lumber for floor joists. National Design Specification for Wood In summary, it appears that two methods of wood Construction and its supplement of wood design values. For the purpose of this paper, structural quality deals Evidently, little analytical concern was placed on construction verification were emerging in the United While dimension lumber dominated the housing with characteristics that affect the strength of lumber, structural capacity prior to the 1900s except by way States in the late 1800s and early 1900s. The first relied market through most of the 20th century, the late not factors such as straightness (although there may of practical experience, although limited discussions on experience with constructed systems for specific 1990s saw a dramatic increase in the use of engineered be relevant correlation between tendency to warp and test data related to structural properties of some applications (i.e., balloon framing of buildings). The wood members such as trusses, wood I-joists, and and structural properties). The primary measures of commonly used wood species may be found in the second and newer method relied on engineering engineered wood panel products (see Table 1).

l /60 d ) l /60 d ) l /60 d ) l /60 d ) l /60 d ) l /60 d ) l /60 d ) l /60 d ) l /60 d ) l /60 d ) l /60 d ) l /60 d ) 15 x d Length over 900 (1- 900 (1- 800 (1- 1,200 (1- 1,300 (1- 1,100 (1- 1,000 (1- 1,200 (1- 1,300 (1- 1,000 (1- 1,100 (1- 1,100 (1- for Columns Working Stresses Working 675 900 975 825 750 900 975 675 750 825 825 600 under 15 x d Length Compression 900 900 800 Stress 1,200 1,300 1,100 1,000 1,200 1,300 1,000 1,100 1,100 Working the Grain Parallel to 3,600 3,800 3,400 3,200 3,500 2,800 3,500 3,000 3,200 3,300 3,900 2,600 Average Ultimate

310 260 170 150 220 220 230 450 150 180 150 170 Stress Working

to the Grain 630 520 340 440 920 290 370 400 340 470 Perpendicular Limit Elastic 70 70 110 120 130 100 100 100 110 Stress Working 300 330 180 170 250 260 270 270 270 Longitudinal Shear in Beam Average Ultimate UNIT STRESSES (psi)

Shearing 80 180 170 100 150 130 170 160 120 210 170 Stress Working the Grain Parallel to 720 710 400 600 590 670 630 300 500 840 690 Average Ultimate 800,000 800,000 Average Elasticity 1,610,000 1,480,000 1,310,000 1,480,000 1,150,000 1,130,000 1,190,000 1,220,000 1,150,000 1,510,000 Modulus of 900 800 900 900 900 800 Bending 1,300 1,100 1,000 1,100 1,100 1,200 Stress Working Extreme

Fiber Stress 6,500 5,600 4,400 4,800 4,200 4,600 5,800 5,000 4,800 4,200 5,700 6,100 Average Ultimate TABLE 8: EARLY ENGINEERING DATA FOR STRUCTURAL TIMBERS (Carnegie Steel Co., 1913) ENGINEERING DATA 8: EARLY TABLE Kind of Timber Longleaf pine Shortleaf pine White pine Spruce Norway pine Tamarack hemlock Western Redwood Bald Cypress Red Cedar White Oak From Carnegie Steel Co. 1913, 310 (as reported in Structural Analysis of Historic Buildings)

Douglas fir

102 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE

800,000 800,000 1,000,000 1,000,000 1,400,000 1,600,000 1,200,000 1,000,000 1,200,000 1,400,000 1,100,000 1,300,000 1,600,000 1,100,000 1,500,000 1,600,000 1,000,000 1,200,000 1,200,000 1,300,000 Elasticity Modulus of 200 200 175 175 300 300 350 350 325 300 275 275 150 150 300 300 300 300 300 300 325 325 500 500 350 350 500 500 325 300 250 250 300 300 250 250 175 175 300 300 to Grain Perpendicular Compression 700 467 550 384 800 533 733 750 800 533 700 467 800 533 900 600 700 467 733 800 800 533 667 750 750 500 800 533 800 533 600 400 667 1,100 1,100 1,100 1,200 1,000 1,100 1,000 Parallel to Grain “Short Columns” 80 53 70 47 90 60 67 90 60 85 57 70 47 67 75 50 70 47 67 67 83 70 85 57 85 57 85 57 70 47 95 63 100 100 100 150 100 100 125 110 Shear ALLOWABLE STRESSES (PSI ) ALLOWABLE Horizontal Bending

900 600 750 500 950 633 867 767 900 600 767 867 667 800 667 933 900 600 733 733 750 500 800 1,300 1,500 1,000 1,100 1,100 1,300 1,000 1,200 1,500 1,000 1,000 1,400 1,500 1,000 1,100 1,100 1,200 Extreme Fiber

1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 GRADE TABLE 9: ALLOWABLE STRESSES FOR STRUCTURAL TIMBERS (Voss and Varney, 1926) and Varney, STRESSES FOR STRUCTURAL TIMBERS (Voss 9: ALLOWABLE TABLE SPECIES western red Cedar, northern white Cedar, Chestnut Cypress Douglas fir Douglas fir (Rocky Mountain) balsam Fir, Gum, red Hemlock, western Hemlock, eastern western Larch, Maple, sugar or hard Maple, silver or soft Oak, white or red Pine, southern yellow Pine, eastern white, western and western yellow Pine, Norway Spruce, red, white, and Sitka Spruce, Engelman eastern Tamarack, 1926, 8 (as reported in Structural Analysis of Historic Buildings without notation regarding safety margins and characteristic structural property and Varney From Voss data used to derive the working stress design values). Modulus of elasticity is assumed represent an average characteristics , but does not differentiate between grades.

ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 103

800,000 800,000 Elasticity 1,600,000 1,600,000 1,600,000 1,600,000 1,600,000 1,600,000 1,500,000 1,300,000 1,600,000 1,600,000 1,600,000 1,600,000 1,600,000 1,600,000 1,200,000 1,200,000 1,200,000 1,200,000 1,200,000 1,200,000 1,200,000 1,200,000 1,000,000 1,000,000 1,200,000 1,200,000 1,200,000 1,200,000 Modulus of 880 600 880 720 880 750 900 2,000 1,800 1,600 1,400 2,000 1,800 1,135 1,135 2,300 2,000 2,000 1,800 1,600 1,200 1,707 1,494 1,322 1,150 1,100 1,100 1,300 1,040 1,100 5 inches Beam and and thicker stringer sizes; ALLOWABLE UNIT STRESS (PSI ) ALLOWABLE 880 750 600 880 720 880 900 2,000 1,800 1,600 1,200 2,000 1,800 1,135 1,135 2,300 2,000 2,000 1,800 1,600 1,200 2,133 1,707 1,280 1.024 1,100 1,100 1,300 1,040 1,100 Extreme Fiber in Bending thickness and less in Sizes; 4 inches Joist and Plank

GRADE Dense superstructural Superstructural and dense structural Structural Common structural Dense superstructural Dense structural No.1 common dimension and timbers No.1 common dimension and timbers Extra dense select structural Select structural Extra dense heart Dense heart Structural square edge and sound Dense No. 1 common Superstructural Prime structural Select structural Heart structural Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural WORKING STRESSES FOR STRUCTURAL LUMBER AND TIMBER WORKING STRESSES FOR MANUFACTURERS’ ASSOCIATION STANDARD COMMERCIAL GRADES STANDARD ASSOCIATION WORKING STRESSES FOR MANUFACTURERS’ GRADED UNDER THE STRUCTURAL GRADE EXAMPLES OF AMERICAN LUMBER STANDARDS ALLOWABLE UNIT STRESSES FOR STRUCTURAL LUMBER AND TIMBER ALLOWABLE (all sizes, dry locations) (HEW, 1931) (all sizes, dry locations) (HEW, TABLE 10: TABLE Cedar, Alaska Cedar, northern and southern white Cedar, Port Orford Cedar, western red Cedar, Cypress, southern Rocky Mountain region Douglas fir, Douglas fir, coast region Douglas fir, inland empire Douglas fir, western Larch, Pine, southern yellow Redwood SPECIES OF TIMBER

104 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE

800,000 800,000 Elasticity 1,000,000 1,000,000 1,100,000 1,100,000 1,100,000 1,100,000 1,400,000 1,400,000 1,500,000 1,500,000 1,000,000 1,000,000 1,200,000 1,000,000 1,200,000 1,200,000 1,300,000 1,300,000 Modulus of 900 720 880 880 720 880 750 600 880 960 900 1,100 1,100 1,300 1,040 1,400 1,120 1,100 1,100 1,200 5 inches Beam and and thicker stringer sizes; ALLOWABLE UNIT STRESS (PSI ) ALLOWABLE 900 720 880 880 720 880 600 880 960 750 900 1,100 1,100 1,300 1,040 1,400 1,120 1,100 1,100 1,200 Extreme Fiber in Bending thickness and less in Sizes; 4 inches Joist and Plank

GRADE Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural Select structural Common structural

WORKING STRESSES FOR STRUCTURAL LUMBER AND TIMBER GRADED UNDER THE STRUCTURAL GRADE EXAMPLES OF AMERICAN LUMBER STANDARDS ALLOWABLE UNIT STRESSES FOR STRUCTURAL LUMBER AND TIMBER ALLOWABLE (all sizes, dry locations) (HEW, 1931) (continued) (all sizes, dry locations) (HEW, The source document (HEW, 1931) did not indicate the margin of safety or characteristic structural values. property values used to derive the above working stress document (HEW, The source The table values were used to create joist, rafter, and girder span tables in the source document based on a stated extreme fiber working stress. document based on a stated extreme span tables in the source and girder joist, rafter, used to create The table values were TABLE 10: TABLE Note:

Fir, balsam Fir, white) white (commercial golden, Noble, silver, Fir, Hemlock, eastern Hemlock, west coast white and red Oak, commercial Pine, California, Idaho, and northern white, lodgepole, Pondosa, sugar SPECIES OF TIMBER Pine, Norway Spruce, Englemann Spruce, red, white, Sitka eastern Tamarack,

ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 105 While difficult to quantify, the references used in the study indicate that a general TABLE 11: EARLY DATA ON WOOD SPECIFIC GRAVITY decline in the structural quality of lumber DESCRIPTION OF WOOD SPECIFIC GRAVITY has occurred. This reduction may be related to the increased use of managed growth White spruce (Canadian) 0.465 lumber, which implies the use of younger, White pine (American) 0.455 faster growing trees. Based on available reports of lumber density and species usage, Black spruce (American) 0.490 it is the authors’ judgment that framing Southern pine (American) 0.872 (dimension) lumber density has dropped from a typical range of 0.4 to 0.65 earlier From Mahon 1885, 125 (as reported in Structural Analysis of in the 20th century to a range of 0.35 Historic Buildings). to 0.55 by the end of the 20th century – approximately a 10 percent reduction in spans of more than 14 feet, 2x10s were recommended lumber density. A similar change in the grade quality when No. 1 grade lumber was used or 2x12 if No. 2 of lumber may also be inferred. This trend would affect lumber was used. (It was generally recommended that member properties as well as connection properties joists be 2 inches deeper or 1 inch wider when lower that are discussed later. While these apparent grade material was used.) One early rule of thumb for changes are amply treated in wood engineering sizing joists and beams from Audel’s states that “Joists specifications and structural property data, the affect longer than 12 times their width [depth] used without on conventional practices suggests the need for re- intermediate supports are apt to crack plastered examination of rules of thumb that are still in use ceilings.” Obviously, the concern here was with today, particularly with respect to system connections serviceability rather than safety. Rules of thumb for and system performance. On the other hand, it should strength were not found in the reviewed literature, but be noted that many engineered wood products that use some general guidelines have been passed down. For laminated veneers and similar methods to create entire example, a span to depth ratio limit of 21 is commonly members or parts of composite members tend to offset considered as a practical design limitation when beams the apparent reduction in dimension lumber quality. or joists are laterally supported to prevent twisting. This rule of thumb would allow a 2x8 (1920s actual size 1-5/8” x 7-1/2”) to span about 13 feet. 4.2 FLOOR FRAMING By the 1930s, standardized lumber grades and stress In the early 1900s, floor joists were typically 2x8 with values (see Table 10) were used to specify maximum spans in the range of 12 feet to 14 feet spaced on 16 spans based on engineering analysis of strength limits. inch centers (though 24 inch on center placement was A deflection limit of 1/360 of span was used to produce indicated for “economical floor construction” when span tables for joists supporting plaster ceilings. Tables a plaster ceiling was not supported by the joists). For were also used to specify maximum horizontal spans

TABLE 12: MAXIMUM SPANS FOR JOISTS AND RAFTERS (feet-inches) (HEW, 1931) LIVE LOAD JOIST SPACING 2x8 2x10 2x12 (psf) (inches) (1-5/8” x 7 -1/2”) (1-5/8” x 9 -1/2”) (1-5/8” x 11-1/2”) Plastered ceiling below (deflection not over 1/360 of span) 10 16 15-4 19-4 23-4 24 14-6 17-3 20-7 20 16 13-11 17-6 21-1 24 12-3 15-6 18-7 30 16 12-11 16-3 19-6 24 11-4 14-4 17-3 40 16 12-1 15-3 18-5 24 10-4 13-1 15-9 No plastered ceiling below 30 16 15-6 19-5 23-3 24 12-10 16-2 19-5 40 16 13-11 17-4 20-11 24 11-5 14-5 17-5

106 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE for sloped roof rafters. Some examples of maximum a maximum stud height to stud depth ratio of 50. For spans are shown in Table 12. buildings over three stories in height, 2x6s or 3x4s were recommended in the lower stories. In modern By the mid-1900s and throughout the remainder of codes with 2x4s of smaller standard dimension spaced the century, building codes used span tables similar 16 inches on center, building height is limited to to Table 12; however, the 1/360 of span deflection two stories and the maximum 2x4 stud wall height limit was eventually applied to all floor joists with is limited to 10 ft. For buildings over two stories in design loads of 30 psf or 40 psf. Separate tables were height, 2x6s or 3x4s are required for the lower stories. eventually created for the selection of roof rafters using Preferred ceiling heights have also changed somewhat different deflection limits (see Section 4.4). In modern over time (see Table 1)which affects the selection of codes, deflection limits–not strength limits–control stud lengths. most floor joist selections. The rationale associated with the elimination of the option to design a floor without a deflection limit when no interior finish was 4.3.2 Plates supported was to improve the “feel” of the floor (i.e., floor vibration or bounce) and also to minimize long- While balloon framing generally used single plates term deflection (creep). However, affordable homes at the top and bottom of walls, “standard” modern well into the mid-1900s can be found with 2x8 floor platform frame construction has adopted the use joist at 16 inch centers spanning as much as 14 to of double top plates (discussed earlier in Sears’ 15 feet over unfinished space. Starting in the 1960s, “standard-built” homes). However, single plates are 2x10 floor joists became as popular as 2x8 joists (both still permitted, and are used occasionally, in modern comprising a total of 75 percent of the practice and affordable platform framed homes, specifically in usually of a “construction” grade lumber). Engineered non-load bearing walls or where loads are transferred wood joists such as parallel chord wood trusses and directly down through studs. I-joists came into use starting in the 1980s (see Table 1). Modern span tables and manufacturer data are 4.3.3 Corners readily available for engineered wood products. Because of differences in “feel” and because of greater Three stud corners have been typical throughout the spans (up to 20 feet and more), many engineered wood 20th century. A 4x4 corner post was sometimes used I-joist manufacturers recommend a deflection limit of in older homes as a hold-over from the 19th century 1/480 of the span. braced frame construction. Two stud corners were also used and are still permitted. 4.3 WALL FRAMING 4.3.4 Headers In the early 1900s, headers were usually considered 4.3.1 Studding unnecessary above typical window and door openings Over the 20th century, actual vs. nominal framing because of the load distributing effects in the walls and member sizes have decreased somewhat and wall floor members above the opening. Thus, only a single framing methods have changed from balloon to or double 2x4 flat-wise was used. Doubled 2x4 stud platform frame. By far, the most common stud spacing framing at window and door openings was considered throughout the 20th century was 16 inches on center; as an enhancement to allow for better trim attachment however, 24 inches on center has also been used and more sturdy support. Regarding headers in primarily for single stories. In the early 1900s, it is platform frame construction, the following 1923 quote clear that 16 inches on center framing was considered was found in Audel’s: necessary for the support of lath and plaster interior “It [platform framing] made the formation of finishes. While 2x4 studding is exclusively mentioned openings for windows and doors easier: a simple in the earlier parts of the century for typical dwelling header (flat-wise 2x4) could be utilized because the construction, 2x6 studs are sometimes used in modern platform above spreads loads from an upper floor or homes to allow for thicker wall cavity insulation (see roof uniformly to the stud walls below.” Table 1). Because of their greater structural capacity and cost, 2x6 studs are sometimes spaced 24 inches For framing above larger than normal doors and on center where 2x4’s would be spaced 16 inches on windows, truss framing using diagonal blocking with center. cripple studs was recommended, though extensive use of this recommended practice is doubtful. Framing In the early 1900s, 2x4s spaced 16 inches on center requirements above window and door openings in the were considered adequate for use in buildings up to early 1900s are summarized in Table 13. three stories in height and for ceiling heights not exceeding 12 to 15 feet. This limit was related to the During the last half of the 1900s, built-up headers weak axis of the stud being braced by wall finishes and ranging in size up to two 2x12s for large openings

ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 107 were provided in span tables in building codes based on various TABLE 13: RECOMMENDED FRAMING ABOVE OPENINGS (HEW, 1931) engineering assumptions OPENING WIDTH RECOMMENDED HEADER FRAMING and loading conditions with disregard for “load 3’ or less 2-2x4 edge-wise in load bearing walls spreading” recognized earlier 1-2x4 flat-wise in non-load bearing walls in the century. No clear reason 3’ to 6’ use a trussed header (practical or technical) for this was found in the reviewed greater than 6’ use a girder (built-up header) literature. It does appear that recognition of different header plane shear tests in 1929 on various wall systems requirements in load bearing vs. non-load bearing representative of the above practices. These tests were conditions existed throughout the century, although conducted to determine the effectiveness of different confusion in the field often resulted in the use of bracing because “no one knew the relative values of headers in either case. different methods.” The bracing tested ranged from horizontal sheathing of green lumber to wood lath and plaster without sheathing. Walls were either solid, 4.3.5 Bracing framed with a single window opening, or framed Wall bracing includes not only the presence of with a window and door opening. The standard wall designated bracing members, but also the contribution construction was designated as horizontal 1x6 board of various sheathing and finish materials applied to sheathing of seasoned lumber fastened to each stud interior and exterior surfaces. In addition, housing with two 8d common wire nails (without interior lath style (i.e., amount and size of openings and plan and plaster finish). It was assigned a relative value configuration) can have significant effects on the of 100 percent (i.e., strength and stiffness factors of amount and type of lateral bracing provided. 1.0). Wall height and length dimensions included two conditions: 9 feet by 14 feet and 7 feet 4 inches by In the early 1900s, wall bracing followed one or more 12 feet. The walls were tested under sufficient vertical of the following reported practices: restraint (load) to prevent overturning from occurring. ◆ no bracing (relying solely on interior lath and plaster The test results for the various solid wall constructions finish and exterior wood siding); are shown in Table 14; results for walls with openings are shown in Table 15. It is apparent that results varied ◆ 1x4 diagonal bracing (let-in or cut-in); or substantially. ◆ horizontal or diagonal board sheathing. Interestingly, the “no bracing” condition (with lath The following 1931 quote from Wood Frame House and plaster only) provided 440 percent more shear Construction explains the recommendation for wall capacity than the horizontal board sheathing without bracing when no sheathing is used: lath and plaster used as a comparative baseline. Diagonal board sheathing also provided significant “Where sheathing is omitted, the wall should be racking strength for solid walls, but, when the diagonal braced, at each corner and beside each doorway, boards were loaded in compression in walls with with let-in strips [1x4] running diagonally from the window and door openings, the shear capacity was less floor line above to the plate or sill below, and nailed than that achieved with lath and plaster with the same strongly at the upper and lower ends as well as at window and door openings. Findings for walls with each intervening stud…Drop siding is more suitable openings showed that any of the bracing methods that than bevel or common siding for direct application included a 1x4 brace, diagonal sheathing, or plaster to studs without sheathing…While rabbeted siding and wood lath provided more shear capacity than for serves to brace the building to some extent, it does not the solid wall with horizontal sheathing only. add sufficient strength to serve in lieu of other forms of bracing. For this reason the building should be With the introduction of 4x8 plywood sheathing braced, or the bracing effect needed should be supplied panels in the mid-1900s, interest in wall bracing using in some other way, as by wood lath and plaster, wood sheathing panels was initiated. However, the diagonal sheathing, or let-in bracing.” standard affordable construction apparently remained with the use of 1x4 let-in braces and non-structural Based on the above quote, it is apparent that interior sheathing. Later, designated bracing was provided finishes (wood lath and plaster) were considered as an by wood structural panels (i.e., plywood) placed adequate primary wall bracing mechanism in the 1930s continuously or intermittently (i.e., at corners and and earlier. However, it was also recognized that other at 25’ intervals along each wall). Also, a significant practices, such as the use of let-in braces or diagonal number of modern homes used proprietary wall board sheathing provided enhanced bracing. bracing panels such as medium density fiber board, and others. By the end of the century, 7/16-inch-thick The Forest Products Laboratory conducted in- oriented strand board (OSB) was commonly used to

108 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE REMARKS No. 20 vibrated 50,000 cycles stopped at 20,000 lb load Test stopped at 20,000 lb load Test stopped at 20,000 lb load Test stopped at 20,000 lb load Test stopped at 20,000 lb load Test First plaster crack at 10,600 lb First plaster crack at 9,900 lb First plaster crack at 12,200 lb First plaster crack at 8,200 lb one million cycles Vibrated

1.0 4.3 4.3 2.8 7.3 1.3 1.6 2.6 4.2 1.0 1.4 5.2 7.5 1.5 1.3 7.5 1.0 7.2 7.9 9.2 6.0 0.5 0.7 1.7 1.7 0.7 FACTOR STIFFNESS

– – 1.0 6.6 7.8 1.1 1.4 3.6 3.5 0.9 1.4 1.4 1.1 1.0 4.4 5.6 7.8 4.9 0.7 0.7 0.8 over 8 over 8 over 8 over 8 over 8 FACTOR STRENGTH

– – – – – – – 2,588 2,800 2,550 2,800 3,700 9,250 9,000 2,330 3,550 3,500 1,700 1,800 2,175 LOAD 17,100 20,100 11,400 14,500 20,300 12,700 (pounds )

DESCRIPTION

8-inch horizontal sheathing, two 12d nails, no braces 8-inch diagonal sheathing, two 10d nails, no braces, boards in tension 6-inch horizontal sheathing, two 8d nails, end and side matched, no braces Plaster on wood lath, no sheathing Plaster on wood lath, 8-inch horizontal sheathing, two 8d nails, no braces 8-inch diagonal sheathing, three 8d nails, no braces, boards in tension 8-inch diagonal sheathing, four 8d nails, no braces, boards in tension 8-inch horizontal sheathing, two 10d nails, no braces Plaster on wood lath, 8-inch diagonal sheathing, two 8d nails, no braces Plaster on wood lath, studs and horizontal sheathing, green lumber then seasoned one month 8-inch horizontal green sheathing, two 8d nails, no braces, panel seasoned one month 8-inch horizontal green sheathing, two 8d nails, no braces, panel seasoned one month 8-inch diagonal green sheathing, two 8d nails, no braces, panel seasoned one month 8-inch diagonal green sheathing, two 8d nails, no braces, panel seasoned one month 8-inch horizontal sheathing, two 8d nails, no braces, alt. sunshine and rain one month 8-inch horizontal sheathing, two 8d nails, no braces 8-inch horizontal sheathing, two 8d nails, no braces 8-inch horizontal sheathing, two 8d nails, no braces 8-inch diagonal sheathing, two 8d nails, no braces, boards in tension 8-inch horizontal sheathing, four 8d nails, no braces 8-inch horizontal sheathing, two 8d nails, no braces 8-inch diagonal sheathing, two 8d nails, no braces, boards in tension 8-inch diagonal sheathing, two 8d nails, no braces, boards in tension 8-inch diagonal sheathing, two 8d nails, no braces, boards in tension 8-inch horizontal sheathing, two 8d nails, herringbone or bridge 2x4 braces 8-inch horizontal sheathing, two 8d nails, cut -in 2x4 braces 8-inch horizontal sheathing, two 8d nails, let -in 1x4 braces, first arrangement 8-inch horizontal sheathing, two 8d nails, cut -in 2x4 braces, second arrangement 8-inch horizontal sheathing, three 8d nails, no braces 9’ x 14’ 7’-4” x 12’ 7’-4” x 12’ 9’ x 14’ 9’ x 14’ 7’-4” x 12’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 9’ x 14’ 7’-4” x 12’ 9’ x 14’ 7’-4” x 12’ 9’ x 14’ PANEL TABLE 14: EARLY SHEAR WALL TEST DATA [Forest Products Laboratory, 1929] [Forest Products Laboratory, TEST DATA SHEAR WALL 14: EARLY TABLE SIZE OF Note: Panel frames consisted of 2x4 upper and lower plates, vertical studs spaced 16 inches, and triple end posts.

ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 109 fully sheath exterior walls. Some statistics on the use of exterior sheathing/bracing are included in Table 1. Various sources of test data on shear resistance of wall materials are summarized in the Residential Structural Design Guide – 2000 Edition (HUD, 2000). Approximate ultimate

REMARKS shear values for various modern wall constructions based on research from the mid-to late-1900s are shown in Table 16. First plaster crack at 1,300 lb First plaster crack at 800 lb First plaster crack at 800 lb First plaster crack at 1,500 lb It is evident that the interior finish material, which is not considered explicitly as bracing, actually was the 3.0 3.1 0.7 1.4 1.4 0.8 1.2 1.5 1.1 2.0 3.3 2.7 2.3 2.4 2.8 4.1 most significant determinant of bracing FACTOR STIFFNESS capacity in many homes built during the first half of the 20th century. During the mid-1900s the preference for interior

2.5 5.0 0.8 4.0 3.9 1.3 1.3 2.2 1.3 3.3 5.4 3.4 1.6 2.2 4.4 3.6 finishes switched from wood lath and FACTOR

STRENGTH plaster to gypsum board, 2 foot wide gypsum “lath” that was finished with

a skim coat of plaster. Soon thereafter,

6,500 3,250 3,400 5,650 3,400 8,500 8,880 4,200 5,800 9,360 the preferred practice became gypsum 2,100 13,000 10,240 10,150 13,900 11,300 LOAD

(pounds ) wallboard using 4 foot wide panels with taped and finished joints. This practice

has remained a standard through the end of the 20th century. It is noted that older

lath and plaster interior finishes may provide up to 8 times more shear capacity than typical gypsum board wall finishes used in modern homes (i.e., 100 plf vs. 800 plf). However, all modern homes use

either structural panel or let-in/metal braces in addition to support provided by interior finishes. Since dwelling lateral (shear) capacity is to some degree dependent on interior finishes, it is important to consider changes in the average size of houses as depicted in Table 1, in amounts of interior wall relative to area, and in dead load (relative to seismic or wind design loads). Data on interior wall linear footage per DESCRIPTION story level as a function of square feet of floor area on a given story level are shown in Table 17. These data are based on a limited sample of house plans that are considered to be representative of a range of home styles constructed in each period. The decrease in the relative amounts of interior walls over the course 8-inch diagonal sheathing, no braces, boards in compression, 6-inch bevel siding 8-inch horizontal sheathing, 1x4 let -in brace 8-inch diagonal sheathing, no braces, broads in tension 8-inch horizontal sheathing, no braces 8-inch diagonal sheathing, boards in tension 8-inch diagonal sheathing, boards in tension 8-inch diagonal sheathing, boards in compression 8-inch diagonal sheathing, boards in compression 8-inch horizontal sheathing, 1x4 let -in braces 8-inch horizontal sheathing, no braces, 6-inch bevel siding 8-inch diagonal sheathing, no braces, boards in tension, 6-inch bevel siding 8-inch horizontal sheathing, 1x4 let-in braces, 6-inch bevel siding Plaster on wood lath, no sheathing Plaster on wood lath, no sheathing, 8-inch horizontal braces Plaster on wood lath, 8-inch diagonal sheathing, no braces Plaster on wood lath, 8-inch horizontal sheathing, no braces, 1x4 let -in braces of the past century is notable. While this trend tends to show a decrease in the amount of ancillary bracing provided by interior walls in newer homes, the lineal footage of exterior walls relative to Window rough openings were approximately 33” x 57” and door 76”. Therefore, the total wall area was 126 square feet, window Window area was 13 square feet, and the door 17.4 feet. 2. 1. Panel frames consisted of 2x4 upper and lower plates, vertical studs spaced 16 inches, triple end posts. floor area tend to increase in the newer homes. Thus, the overall bracing impact (considering the changes to interior and window window window and door window and door window and door window and door window and door window and door window and door window and door window and door window and door window and door window and door window and door window and door Notes: OPENINGS TABLE 15: EARLY SHEAR WALL TEST DATA FOR 9’ X 14’ WALLS WITH OPENINGS [Forest Products Laboratory, 1929] WITH OPENINGS [Forest Products Laboratory, FOR 9’ X 14’ WALLS TEST DATA SHEAR WALL 15: EARLY TABLE exterior walls) may be somewhat offset

110 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE TABLE 16: ULTIMATE SHEAR VALUES FOR TYPICAL MODERN WALL CONSTRUCTIONS 1x4 Let-in brace >600 lbs/ea (tension) 2,000 lbs/ea (compression) Metal T-brace (tension only) 1,400 lbs/ea 1/2” Gypsum Wall Board (single side, min. 4d cooler nails at 12”oc) 100 plf 3/8” Plywood or 7/16” OSB (G=0.5, 8d pneumatic nails at standard 6/12 spacing) 650 plf Exterior 7/8” PC stucco and metal lath w/nails 500-750 plf w/staples 750-1,580 plf

TABLE 17: INTERIOR WALL AMOUNTS [lin. ft. as a percent of floor area of story] OLDER HOMES (early 1900s)1 MODERN HOMES (late 1900s)2 1 story 9 percent ± 1 percent 1st floor of 1 to 2 story 4.3 percent ± 1 percent 1st floor of 2 story 6 percent ± 1 percent 2nd floor of 2 story 7.9 percent ± 1 percent 2nd floor of 2 story 9 percent ± 1.5 percent Notes: 1Values based on a small sample of traditional house plans in Sears Catalogues (1910 – 1926) including affordable and more expensive construction of 1 and 2 stories. 2Values based on a small sample of representative modern home plans (1990s) including economy and move- up construction (no luxury homes). by these two countervailing trends. Uncertainty in the Since engineering methods have failed to offer effects of increased irregularity in plan configuration reasonably accurate explanations of the system of newer homes must also be considered relative to effects related to hip or valley rafter design, similar possible impact on resistance to lateral loads. However, rules of thumb are still in practice today (unless an one recent study of homes following the Northridge engineered design is required). By the mid-1900s, Earthquake seems to indicate that irregularities in rafter framing (and also floor joists) were commonly wall line offsets cannot be directly associated with provided in engineered span tables using certain design any noticeable trend in performance of single family assumptions and methods of analysis considering homes (HUD, 1999). The data summarized in this single elements and not systems. Newer span tables are section is provided to suggest the need for a more based on updated lumber properties, but engineering detailed and thorough evaluation of changes in assumptions similar to those used earlier in the century bracing found in homes over the past century. Thus, are found in all modern building codes for residential the simple comparisons as suggested in this report are construction. During the mid-1900s, engineered wood not absolute or complete treatments of this subject. roof trusses were introduced and by the late-1900s were used in a great majority of new homes (see Table 1).

4.4 ROOF FRAMING 4.4.2 Roof Sheathing

4.4.1 Rafters In the early 1900s, roof sheathing of 1x6 or 1x8 boards, or minimum 1x3 furring (spaced sheathing) spaced As noted earlier, roof rafters were typically 2x4 or 2x6 according to weather exposure of wood shingles (up in the early 1900s. The horizontal span of rafters and to 6 inches on center) was typical. A minimum of two the rules of thumb mentioned previously for joists 8d common wire nails were typically used to fasten were typically used for rafter members as well. For hip random-length boards to each roof rafter. In the mid- and valley rafters, the following rule of thumb from 1900s plywood roof sheathing entered the market and Light Frame House Construction was apparently in use in soon became the standard. By the late 1900s, most the early part of the 20th century: roofs were sheathed with some form of wood structural panel sheathing, primarily 7/16-inch-thick OSB ◆ up to 12 foot horizontal span use a single hip rafter 2 (see Table 1); board sheathing methods had become inches deeper or 1 inch thicker than rafters; and practically extinct. Nailing requirements and types ◆ over 12 foot horizontal span use a doubled rafter for of fasteners changed to accommodate the panels and the hip rafter. newer tools, such as pneumatic nail guns.

ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 111 4.5 FASTENERS AND CONNECTIONS conservative and simple as to not require exact specification. While connection requirements for Trends in the treatment of connections in housing modern residential wood framing can be found in during the 20th century provide important insights building codes, no data is available that quantifies the into changes in the structural characteristics of homes. variation in actual fastening techniques or practices This section reviews some of the changes in fastening used in the field. Observation tends to suggest that practices and materials. Where found in the literature, the variation is quite large. Very little technical data is data on structural characteristics of various fasteners or available to explain the actual performance of various connections are summarized. fastener and material choices found in modern home Wire nails have been the predominant fastener for construction practice, particularly when considered at wood framing connections throughout the 20th a system level (e.g., multiple joints and fasteners in a century. Up to the 20th century, the most common load path). Some studies of this nature are summarized nails used were wrought iron or cut nails, which were in the Residential Structural Design Guide – 2000 Edition preceded by the use of wooden pegs and special heavy (HUD, 2000). timber connection details (i.e., wood joinery). Cut nails The following connection requirements or practices were quickly replaced by common wire nails in the are excerpted and summarized from sources reviewed earliest parts of the 20th century. However, it is worth in this study. They are based on recommendations noting that Audel’s reports test data indicating that provided in various framing guidelines and early code cut nails provide as much as 2 to 3 times the “holding documents and, therefore, may not represent actual capacity” of common wire nails of similar size. The field practice during the different time periods or in tests were conducted with several repetitions and wood different locales. species, including hardwoods and soft woods and dense soft woods. It is presumed that the difference in withdrawal capacity can be explained by the wedging 4.5.1 Early 1900s action created by the tapered shank of a cut nail. Sill to Foundation—Indicated as “desirable” to anchor Cut nails continued to see infrequent use for some sill to foundation (especially if high wind is possible); applications such as hardwood flooring, but eventually recommend 3/4 inch bolts extending 18 inches into they became obsolete. In early framing practice, concrete foundation wall with OG washer and nut. specifications often called for heavier loaded joints Recommendations for sill bolt spacing ranged from 6 or thicker materials to be “securely spiked together.” feet to 12 feet on center. Evidently, anchoring was not Spikes are similar to common wire nails, but are larger a required or common practice for typical construction in diameter and greater in length than common wire at the beginning of the 20th century. nails. However, from the literature surveyed, it appears that for home building in the early 1900s, spikes may Joist to Sill or Wall (depending on type of framing)—- have been considered to be 20d common wire nails. (1) Balloon and braced framing: spike securely to side of Rules of thumb for nail selection in the early 1900s are studs (two near bottom and enough at top to hold in paraphrased as follows from Audel’s: place during construction). (2) Platform framing: joists should be securely toe-nailed to plate with not less that “Use one penny size for each 1/8-inch of thickness for 8d or 10d nails; box headers should be spiked securely typical wood density. For softer wood use up to two into ends of joists with 20d nails (remember, the box penny-weights larger, and for harder/denser wood use header or band joist was treated as a continuous header one to two penny-weights smaller to prevent cracking above all openings in walls below). of wood.” Built-up Girders—Use 10d common wire nails at 12 In the last half of the 1900s, box nails with a smaller inches on center top and bottom (staggered) to keep shank diameter and a resin coating to increase holding individual members from buckling separately or failing were used to some unknown extent. By the late 1900s, independently. pneumatic fasteners dominated the market. Various fastener sizes and types are addressed in the Residential Joist Headers for Floor Openings—End nail through Structural Design Guide – 2000 Edition (HUD, 2000) and inside trimmer (if doubled trimmer joists) into end other wood design or technology references. grain of each single or built-up header member with two 20d spikes for 2x6; 3 for 2x8 and 2x10; or 4 for Early requirements for nailing were as much a result of 2x12 and 2x14. constructability considerations as for structural reason, and varied depending on a particular connection Stud to Top and Bottom Plates—“Desirable” to end-nail and its perceived role in the structural system. Often, using two 20d common wire nails. the older requirements for connections used vague Ribband to Stud—Let-in 1x6 into studs to support terms such as “spike securely” or “adequately nail.” joists in balloon framing; secure ribband to each stud Perhaps this subjective approach was in realization with two 8d common wire nails. that the fastening practice, material choices, and framing methods of the early 1900s were sufficiently Rafter to Ceiling Joists or Collar Beams (cross ties)—

112 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE “Solidly nail” rafters to joists; connect a ceiling joist to confirm that quality problems existed, but does not to every rafter if shallow slope roof or to every second allow a quantitative assessment of the degree, frequency, or third rafter for steep roofs. Some old construction or implications of such problems as related to structural drawings suggest that 3 to 5 nails may have been used performance in newer or older homes. It appears that for this connection. the tradespeople of yesterday were just as subject to human error as they are today. Rafters to Ridge Board—Toenail or end-nail rafter to ridge board; “not of great significance structurally,” but However, assuming no significant change in construc- required to hold in place during construction. tion quality, certain changes in construction materials and methods may justify a greater concern in Rafters to Wall Plate—Toe nailing was common modern times on the basis that the techniques are practice; however, nail sizes and numbers were not less “forgiving” of mistakes or tolerances implicit to shown or reported in any of the literature surveyed. reasonable standards of workmanship. For example, Like foundation anchor bolts, it appears that anchoring modern framing members are somewhat smaller of roofs was left to the realm of “accepted construction and require greater precision in fastener installation. practice.” Pneumatic fastening methods and panelized sheathing Valley and Hip Rafter to Ridge—Provide “adequate products tend to create situations where “blind” fastening to ridge to prevent pulling apart.” connections are made to underlying framing members without as close a control as inherent with hand- Sheathing Boards to Wall or Roof Framing—Two 8d driven nails to secure boards. While such problems can common nails per board up to 1x8; three 8d common be avoided with appropriate controls, newer materials nails for greater than 1x8. In the early 1900s cut nails and methods (including more varieties and options were still frequently used for this connection. than in the past) do seem to place the burden of a greater standard of care on the tradesperson. 4.5.2 Late 1900s The mid-1900s can be considered as a transition period in fastening technology. During this period, pneumatic 6.0 SUMMARY AND CONCLUSIONS fasteners began to be used (discussed below). Box nails were also used in place of common nails, but to an Significant changes to construction materials and unknown degree. Other changes that affected fastener methods have occurred over the past century that specification included the introduction of plywood affect the economy and structural performance of sheathing, and the use of metal plate connected wood homes. In some cases it appears that change has trusses in place of traditional rafter and joist framing. increased structural performance while, in other cases Special metal connectors, such as joist hangers, also structural performance was reduced. It also appears came into use for certain connections or conditions. that different levels of value (i.e., balancing of cost versus performance) have been applied throughout the By the late 1900s, pneumatic fasteners were used century to meet varied housing needs or desires in the predominantly in the home building industry for nation. As a result, minimums based on a compelling framing purposes. The requirements for pneumatic need for affordable housing have co-existed with “up- fasteners (nails and staples) were provided in a code grades” used in homes sold to more affluent buyers. evaluation report (NER 272). However, connection In such a manner, housing supply has served a diverse schedules in codes still addressed primarily common demand with needed flexibility in establishing an wire nails. Thus, the connection requirements for appropriate definition of value based on individual specific fastener types in common use or approved for buyers or market segments. use are not consolidated. This condition may explain the variations in actual practice that may fall above or Some significant changes to housing construction below the minimums implied by or explicitly defined methods and materials discussed in this report are in modern building codes. summarized as follows: ◆ Separate concrete spread footings, introduced in early 1900s, are found on nearly all homes by the end of the century. In fact, several enhancements to 5.0 CONSTRUCTION QUALITY foundation construction have occurred over the past No reliable source of data was found regarding trends in century. construction quality over the course of the 20th century. ◆ Framing method switched from balloon to platform However, it should be noted that complaints and frame technique. concerns with shoddy construction in the references used in this study seem to indicate that it was just as ◆ In 1900, lumber was ungraded and largely reliant on much a concern at the beginning of the century as the locally available species and “sorts”. Later, lumber end. Unfortunately, the significance of such concerns grades were standardized and resources became more remain in the realm of anecdotal evidence, which serves dependent on managed forests and fewer species.

ARCHITECTURE Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 | 113 ◆ Lumber size was originally based on full dimensions only when adhesive coatings on pneumatic nails are (i.e., actual size of a 2x4 was 2 inches by 4 inches). not considered. Thus, withdrawal capacity of nails During the 1900s, the sizes of “finished” dimension for certain joints may have changed dramatically lumber were reduced in several stages to a standard depending on the effectiveness of adhesives on newer thickness of 1.5 inches and standard widths of 3.5, coated nails. Changes in the shear capacity of certain 5.5, 7.25, 9.25, and 11.25 inches for nominal 2x4, 2x6, joints, such as sheathing connections, also occurred 2x8, 2x10, and 2x12 dimension lumber, respectively. as a result of the general reduction in nail diameters. ◆ At the end of the 20th century, engineered wood ◆ Construction quality has been a concern through products quickly gained acceptance as alternatives to the 20th century with little evidence to suggest dimension lumber used primarily in sheathing, floor that any substantial change (good or bad) has framing, and floor girder applications. occurred. However, there are some obvious changes ◆ A complete change from boards to engineered wood in materials and tools that require more precision structural panels (i.e., OSB and plywood) happened in construction; thus, there is a greater potential for relatively quickly early in the second half of the 20th error, particularly in connections. This problem is century. not helped by the numerous choices for fasteners (including staples, etc.) now on the market, and the ◆ Headers for windows and doors have seen significant lack of simplicity and uniformity in the regulations change. At the beginning of the century structural that govern connection requirements in modern headers, as such, were not normally used over construction practice. openings; instead there was acknowledgement of system effects in distributing loads over wall openings. By the end of the 20th century, header 7.0 RECOMMENDATIONS requirements became more complicated requiring different tables to be considered under various The findings and conclusions of this study suggest that conditions. For unspecified reasons, the earlier certain modern house construction practices should acknowledgment of system effects was abandoned. be carefully evaluated in view of changes in historic In addition, the apparent desire to simplify practice. Some specific recommendations include: construction in the field has often resulted in the 1. Re-evaluate, simplify, and prepare specific details “worst-case” condition being applied to all headers for connections that balance structural needs with in order to eliminate confusion. the intuition and capability of the tradesperson. For ◆ Wall bracing has apparently seen little change in example, can two specific sizes of pneumatic nails effective capacity required by standardized testing be successfully used to specify all or most framing of wall segments, though materials have changed connections in a typical house? during the course of the 20th century. Specific 2. Wall bracing practices should be re-assessed based on bracing requirements were implemented in the last changes in the style, size, and interior finishes used half of the century. However, interior finishes have in modern homes as compared to older homes (early changed from lath and plaster to gypsum wallboard 1900s). which has the effect of lowering the “reserve capacity” found in older homes relative to newer 3. Practices for header sizing and engineering analysis homes. Changes in house style, size, and design of homes in general should incorporate more of interior space have also affected the “reserve efficient system-based design principles that were capacity.” However, more recent trends toward total inherently understood in the design and framing sheathing with structural material such as OSB can practices in the early 1900s. readily compensate for other “losses.” ◆ Fasteners changed, first from cut nails to common 8.0 BIBLIOGRAPHY wire nails, then to pneumatic fasteners. Box or sinker nails were also used. However, little quantitative Annual Builder Practices Survey, NAHB Research Center, information is available to determine the functional Inc., Upper Marlboro, MD. or performance rationale for connections found in the Architectural Graphic Standards, 5th Edition, Charles historic practice or in building codes (not to suggest George Ramsey and Harold Reeve Sleeper, 1956. that data from various single fastener tests do not Audel’s Carpenters and Builders Guide (Vol. 1, 2, 3, and 4), exist in large quantity). The withdrawal capacity of an Theo. Audel & Co. -Publishers, New York, NY, 1923. 8d cut nail used at the beginning of the 20th century for sheathing was as much as 2 to 3 times more Cotton Fields No More: Southern Agriculture 1865-1980, than a comparable 8d common wire nail according Gilbert C. Fite, The University Press of Kentucky, to early tests. The 8d common wire nail, in turn, Lexington, KY, 1984. provides greater withdrawal capacity when compared Dwelling House Construction, Fourth Edition, Revised, by to most 8d (0.113 inch diameter) pneumatic nails Albert G. H. Dietz, The MIT Press, Cambridge, MA, commonly used at the end of the 20th century, but 1974.

114 | Review of Structural Materials & Methods for Home Building in the U.S.: 1900-2000 ARCHITECTURE Evaluation of Housing Performance and Seismic Design through frame wall construction, containing building Implications in the Northridge Earthquake, U.S. paper or plaster properly applied, is negligibly small Department of Housing and Urban Development, (0.1 to 0.3 cubic feet per hour with a 15 mph wind- Washington, DC, 1999 induced pressure difference). It is also reported that Housing at the Millennium, Facts, Figures and Trends, the United States Bureau of Standards had conducted National Association of Home Builders, Washington, tests on the strength, rate of air penetration, and DC, 2000. moisture proof properties of building papers. Asphalt impregnated papers were reported to weigh from 66 Housing Statistics, U.S. Census, Washington, DC. to 163 pounds per 1,000 square feet. It was noted that Light Frame House Construction, U.S. Department of building paper “must be selected and put on much Health, Education, and Welfare (HEW), Washington, more carefully than is ordinarily done.” DC, 1931. One 1930s framing guide (HEW, 1931) encouraged Minimum Property Standards for One and Two Living the use of exterior board sub-sheathing for its Units, FHA No. 300, Federal Housing Administration, structural bracing benefits and for comfort benefits Washington, DC, 1958. in cold or hot climates since “wood is one of the best Old House Measured and Scaled Detail Drawings for Builders natural insulators.” In addition, one drawing of roof and Carpenters, W. A. Radford, Dover Publications, framing did indicate “insulation material” placed Inc., New York, NY, 1983. between ceiling joists, which may suggest the relative One- and Two-Family Dwelling Code, Council of American importance placed on insulation in roofs as compared Building Officials (CABO), Falls Church, VA, 1989 and to other locations. The same guide later describes air 1992 editions. leakage and thermal conduction as primary sources of heat loss, and encourages the use of thermal insulation Pneumatic or Mechanically Driven Staples, Nails, P-Nails, and weather striping of doors to save on the rising cost and Allied Fasteners for Use in All Types of Building of coal as well as other sources of heating energy (fuel Construction (NER-272) – Council of American oil, electric, etc.), and percent reductions in air leakage Building Officials, Falls Church, VA, 1989. were cited for practices such as weather stripping and Residential Structural Design Guide -2000 Edition, tightly fitting doors. prepared by NAHB Research Center, Inc., for the U.S. Department of Housing and Urban Development, The National Bureau of Standards (Journal of Research, Washington, DC, 2000. Vol.6, No.3), reported fuel savings for combinations of weather-stripped doors, insulation, and double Sears, Roebuck Home Builder’s Catalog, 1910 Edition, (storm) windows. The savings were reported to Dover Publications, Inc., NY, 1990. range from 10 to 60 percent. The higher values were Small Housing of the Twenties, the Sears Roebuck 1926 reported for use of 1-inch insulation (probably exterior Catalog, Rover Publication, Inc., NY, 1991. wood sheathing) and double windows. It is noted Structural Analysis of Historic Buildings, J. Stanley Rabun, that if tarred paper is not placed over sheathing (i.e., John Wiley & Sons, Inc., New York, NY, 2000. board sheathing is omitted) it is probably not worth Wood Frame House Construction, Edited by Gerald E. installing because of air leakage between laps in the Sherwood and Robert C. Stroh, Ph.D., for the National building paper. It is not clear that the function of Association of Home Builders, Armonk Press, Armonk, moisture protection was considered reason enough to NY, 1988. justify the use of building paper. In general, energy efficiency did not become a serious consideration in home construction until later in APPENDIX A THERMAL INSULATION the 1900s. The Minimum Property Standards (HUD, Very little mention of any requirement for energy 1958) gave requirements for insulation based on a efficiency such as thermal insulation was found in rudimentary calculation method. By the late 1900s, the historical sources reviewed (see Bibliography). For more sophisticated energy codes had been developed example, no information on thermal insulation was and relatively high levels of insulation were required in virtually every new home. The availability of materials found in the Sears catalogues, which were considered to enhance energy efficiency also flourished (e.g., an exhaustive catalogue for building materials, double glazed windows, various insulation types with although the use of tarred felt paper underneath high thermal resistivity, sealing and weather-stripping flooring to prevent draftiness and under the siding for technologies, etc.). In addition to energy codes that rot protection was mentioned. addressed new construction, tax incentive programs Tarred paper was also recognized as an air barrier to were introduced in the 1970s to encourage insulation of prevent air leakage through walls in “poorly built” older homes. In addition, credits were offered through homes in a University of Wisconsin study in the early energy efficient mortgage financing programs and 1900s. This study reported various infiltration rates demand-management programs offered by various through frame walls and found that “air infiltration utility companies.

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