An Introduction for the Southeast i ORG . CRAWLSPACES . WWW nergy.org ACES P S RAWL Energy C by Advanced LOSED C An Introduction to Design, Construction and Performance An Introduction to Design, Advanced Energy, 909 Capability Drive, Suite 2100, Raleigh, NC 27606, Phone: 1-919-857-9000, Fax: 1-919-832-2696, www.advancede 909 Capability Drive, Suite 2100, Raleigh, NC 27606, Phone: 1-919-857-9000, Fax: 1-919-832-2696, Advanced Energy, H ii Closed Crawl Spaces IGH -P ERFORMANCE John Tooley, AdvancedEnergy Jeff Tooley, TheHealthyBuildingCompany Dan Tingen, Tingen Construction Billy Tesh, PestManagement,Inc. Colby Swanson,AdvancedEnergy T Isaac Savage,HomeEnergyPartners Champaign William Rose,UniversityofIllinoisUrbana- James EarlRich,Rich’s Heating&Air Dan Preisach,Myers-Preisach,Inc. Steve McLeod,IndoorEnvironmentalSystems Marshall Knight,KnightBuilder Arnie Katz,AdvancedEnergy Ed Gerhardt,Sure-LockHomes Buddy Holliday, HazardMitigationContractors,Inc. Carl Falco,NCDepartmentofAgriculture Steve Elder, ElderEnterprises,Inc. Skye Dunning,BuildingPerformanceSpecialists Francis Conlin,mSolve Brian Coble,AdvancedEnergy Association Greg Baumann,NationalPestManagement of thisdocument. constitute orimplyanendorsementofthecontents However, theirrevieworcontributiondoesnot from orimprovedbytheirthoughtfulcontributions. and organizationslistedbelow. Ithasbeencreated collaboration withandguidancefromtheindividuals This documentistheresultofmanyhours ACKNOWLEDGMENTS im Sellers,HealthyHomeEnvironment H OMES Commission. established in1980bytheN.C.Utilities approaches toenergy. AdvancedEnergywas and environmentalbenefitsthroughinnovative energy investment.Itsmissionistocreateeconomic residential customersimprovethereturnontheir national resourcetohelputility, industrialand asastateand non-profit corporationthatserves Advanced EnergyisaRaleigh,N.C.,based,private Project Consultant Project Director Project Manager AUTHORS copyrighted document. translate, duplicate,exhibitandpresentthis Governmental purposestopublish,distribute, nonexclusive, irrevocable,worldwidelicensefor others actingonitsbehalfaroyalty-free, for itself and 00NT40995. TheGovernmentreserves Department ofEnergyunderContractNo.DE-FC26- This documentwaswrittenwithsupportoftheU.S. © 2005AdvancedEnergy COPYRIGHT Bill Warren EnergyServices Bill Warren, Advanced Energy Bruce Davis, Advanced Energy Cyrus Dastur, Government oranyagencythereof. necessarily stateorreflectthoseofthe UnitedStates opinions oftheauthorsexpressedhereindonot Government oranyagencythereof.Theviewsand recommendation, orfavoringbytheUnitedStates not necessarilyconstituteorimplyitsendorsement, name, trademark,manufacturer, does orotherwise by trade commercial product,process,orservice owned rights.Referenceshereintoanyspecific represents thatitsusewouldnotinfringeprivately apparatus, product,orprocessdisclosed, completeness, orusefulnessofanyinformation, any legalliabilityorresponsibilityfortheaccuracy, makes anywarranty, expressorimplied,assumes nor anyagencythereof,oftheiremployees, Government. NeithertheUnitedStatesGovernment sponsored byanagencyoftheUnitedStates This documentwaspreparedasanaccountofwork the DOE. author(s) anddonotnecessarilyreflecttheviewsof recommendations expressedhereinarethoseofthe any opinions,findings,conclusions,or under ContractNo.DE-FC26-00NT40995.However, sponsored bytheU.S.DepartmentofEnergy(DOE) This documentwaspreparedasanaccountofwork disclosed inthisdocument. information, apparatus,methodorprocess for damagesresultingfromtheuseof,any assumes anyliabilitywithrespecttotheuseof,or report maynotinfringeprivatelyuponrights;or(2) apparatus, methodorprocessdisclosedinthis this document,orthattheuseofanyinformation, completeness orusefulnessoftheinformationin express orimplied,withrespecttotheaccuracy, its behalf:(1)makesanywarrantyorrepresentation, Neither AdvancedEnergynoranypersonactingon DISCLAIMER An Introduction for the Southeast iii ORG . CRAWLSPACES . WWW ...... 49 ...... 45 ...... Crawl ...... 45 Space ...... emperature Conditions ...... 54 Overview ...... 45 Crawl Spaces. .Basic Maintenance for 48 Overview ...... 49 Quantifying Existing Crawl Spaces.49 . . Field Study Experimental Setup . . . . .50 Instrumentation and Data Collection.51 . Moisture Performance ...... 52 T Energy Performance ...... 54 Radon Measurements ...... 56 Mold Sampling Results ...... 56 Research Implications ...... 57 Steps for Improving a Wall-vented Wall-vented Steps for Improving a opics related to improving a wall-vented crawl to improving a wall-vented opics related Continued on next page Section 6 Research Results Presents results from Advanced Energy research, including detailed results comparing the performance of closed crawl spaces to wall- vented crawl spaces in a multi-year controlled experiment in eastern North Carolina. Section 5 Section Crawl Spaces Wall-vented Improving T wall-vented crawl space and converting a space. Retrofitting an space to a closed crawl a variety of existing crawl space presents not usually present in complications that are new construction...... 25 ...... 39 all Insulation . .30 ...... all Insulation . .34 ...... Control Methods ...... 25 Floor Insulation ...... 28 ...... W Residential Code ...... 39 Carolina Residential Code . . . . .40 . . . Code Issues ...... 42 Floor Insulation ...... 32 W Construction Sequence ...... 36 Overview ...... 25 Historic Origins ...... 39 Recommended Humidity Recommended Humidity Air and Sample Design: Supply Sample Design: Supply Air and Revising the North Carolina Requirements of the New North Other North Carolina Residential Sample Design: Dehumidifier and Sample Design: Dehumidifier and Sample Closed Crawl Space Section 4 Building Codes A brief history recent of crawl space regulation, revisions to the North Carolina residential code, and recommendations related to the new code language. Section 3 Section and Construction Sample Designs Process crawl spaces are Sample designs for closed section drawings with provided as architectural drawings may be details called out. These of permit copied and used as components specifications, applications or project depending on local requirements...... 1 ...... 7 ...... 19 Blocking Sources ...... 8 Facilitating Removal ...... 12 orking With Code Officials ...... 20 Overview ...... 19 Defining the Design ...... 19 W Overcoming Conventional Wisdom . . .20 Managing Labor ...... 20 Managing Job-Site Logistics ...... 20 Providing Quality Assurance ...... 22 .23 . . Establishing a Contract and Pricing Summary ...... 23 Overview...... 7 ...... Moisture Management ...... 7 Pest Control . . .13 ...... Combustion Safety ...... 15 Thermal Insulation...... 16 . . Fire Safety ...... 16 ...... Radon Safety ...... 17 Summary...... 17 . . Background ...... 2 Audience ...... 2 Using this Guide . .3 ...... The Ventilation Myth...... 4 . ONTENTS able of Contents able of Section 2 Implementing a Closed Crawl Space Section 1 Components Recommended Design Introduction T C ABLE OF T H iv Closed Crawl Spaces IGH -P ERFORMANCE providers andmoredetailedsourcesofinformation. space projectsaswellreferencestoservice equipment usedinAdvancedEnergy’s closedcrawl Lists sourcesofsupplyformaterialsandmonitoring Resources andReferences Section 8 information andseveralreferences. and cleanupofmold,butofferssomebasic complete guidancewithregardtotheidentification mold. Thisguidedoesnotprovidethoroughor Presents basicanswerstocommonquestionsabout Common QuestionsAboutMold Section 7 Index Appendices hudICenU xsigMl . . . .60 Should ICleanUpExistingMold Other Resources . ..64 Resources Other T ..63 Resources Online ..63 Services and Products ..62 Sick? People Make Mold Does . . .60 TestMold? I for Should ..59 Mold? Is What D. Glossary ofAcronyms D. Glossary C. Wood MoistureContentat ..66 Chart Psychrometic Simplified B. . . .65 ofDuctSealing A. QuickOverview cnclRfrne ..64 References echnical in MyCrawlSpace? eaieHmdte ..67 Humidities Relative Different Temperatures and n brvain ..68 Abbreviations and ..69 H ..63 ..59 OMES ..65 T BEOF ABLE C ONTENTS An Introduction for the Southeast 1 ORG . CRAWLSPACES . WWW for complete “Conditioned” A closed Not all closed crawl spaces are conditioned. crawl space that is truly conditioned must have thermal insulation located at the perimeter wall and a Unless barrier covering any foam plastic insulation. spaces specifically designed to do so, closed crawl generally will not maintain the minimum 68° F (20° C) winter temperature required to qualify as a “conditioned area” as defined in the North Carolina (and International) residential code. The words “closed,” “sealed,” “unvented” or “conditioned” will likely continue to be used interchangeably to refer to a variety of crawl space air. designs that do not have ventilation with outside Designers, installers, and code officials will need to make sure that the chosen specifications and requirements are clearly understood, whichever name is used. and implies that any small, unsealed air leakage path and implies that any small, provides grounds for failing an inspection. In experience, it is inappropriate to Advanced Energy’s yet require code officials to use such a stringent, vague, standard for enforcement. www.crawlspaces.org release of the North Carolina code in 2006. North Carolina code release of the on the that are based Design guidelines are of this new code language requirements highlighted in the guide. Visit research reports, short videos on key concepts, research reports, short an electronic copy of article links, or to obtain versions of code this document. When online crawl spaces are language related to closed be linked. available, they will also The North Carolina residential code does not define a The North Carolina residential code does not closed crawl space as requiring a sealed vapor which Advanced Energy recommends. retarder, from Installers can differentiate this improved design it “closed other closed crawl space designs by calling Furthermore, it is impractical to with a sealed liner.” a crawl space. The term “sealed perfectly air-seal crawl space” suggests an extreme level of air sealing Why is the new design called a Why is the new “closed” crawl space? the This guide uses the term “closed” to describe but alternative to a wall-vented crawl space design, term several other terms are commonly used. The code. “closed” is used in the North Carolina building Here is a brief background on why “closed” was chosen over other options: “Unvented” In fact, several closed crawl space designs are common Two vented, just not with outside air. from a techniques are ventilation with conditioned air air from duct system and ventilation with conditioned the living space. “Sealed” humidity below 65% during the same period. 65% during the same humidity below homes built also shows that the The research 15% on spaces save up to on closed crawl cooling usage for heating and annual energy homes built on wall- when compared to the vented crawl space foundations. findings supported a The Princeville project Carolina residential 2004 revision of the North space construction. code that governs crawl is currently available The new code language with the next print for use and will be enforced NTRODUCTION This guide is an introduction to the design This guide is an introduction code components, field implementation, performance of requirements, and measured in central and eastern crawl space construction a short section describes North Carolina. While owners can take steps that builders or property crawl to improve traditional wall-vented this guide focuses on a spaces, the majority of spaces that are not new design: closed crawl air. ventilated with outside Many of the guidelines and much of the background information presented in this guide comes from the results of an ongoing Advanced Energy research project, started in the eastern North Carolina town of Princeville in 2001. The Princeville research project compares the performance of wall-vented and closed crawl space foundations in a controlled Additional recommendations come from study. other Advanced Energy research projects, including investigations of crawl space failures, and from collaboration with closed crawl space installers across North Carolina. The Princeville research project has shown that closed crawl spaces do a much better job of do controlling crawl space moisture levels than well-built wall-vented crawl spaces. While relative humidity in the wall-vented crawl spaces exceeds 80% for the majority of the spring and summer months, the Princeville closed crawl space designs control relative I NTRODUCTION I H

2 Closed Crawl Spaces IGH -P ERFORMANCE of thesecomplaints. insulation contractorsroutinelybear thebrunt Builders, mechanicalcontractors and floors, andmolddamageinthehomeabove. humidity, mustyodors,buckledhardwood framing. Homeownerscomplainofhigh ducts, andinsomecases,rotthewood plumbing pipes,airconditioningequipmentor on surfaces,condensationtrussplates, wood moisturecontent,visiblemoldgrowing beads ofmoistureinfloorinsulation,high crawl spaceinthespringorsummerandfind building professionstoenterawall-vented It isanalltoocommonexperienceinthe moisture andinsulationproblems. spaces canalsohostavarietyofserious Unfortunately, traditionalwall-ventedcrawl heating andairconditioningsystems. plumbing, electricallines,andductworkfor convenient spacesinwhichtolocate foundation forflooringonslopingsites,and functional intermsofprovidingalevel Crawl spacesareinexpensivetobuild, homes peryear. million existinghomesandaround70,000new southeast, wheretheyarefoundinover9 existence. Theyareespeciallycommoninthe estimated 26millionsuchhomesalreadyin yearandan built oncrawlspacesevery States, withapproximately250,000newhomes building constructionthroughouttheUnited Crawl spacefoundationsarewidelyusedin Background H OMES spaces canmaintainrelativehumidity below surfaces inthecrawlspace.Closed crawl experience condensationonavariety of supports moldgrowthandtheyroutinely humidity belowthe70%thresholdthat southeast, theycannotmaintainrelative spaces maybeabletocontrolrotinthe growth. Whilewellbuiltwall-ventedcrawl conditions thatleadtocondensationandmold Ideally theyshouldalsominimizethe foundations shouldcertainlybefreeofrot. As aperformancegoal,crawlspace southeastern climate. liability ofmoldandmoisturedamageinthe dramatically reducetheriskandassociated by aproperlyclosedcrawlspacecan existing homes.Themoisturecontrolprovided closed crawlspacesystemsinbothnewand invest theadditionalefforttoincorporate growing numberofconsumersandbuildersto awareness ishelpingtodrivedemandfroma the needtocontrolmoistureinhomes.This muchmoreawareof the constructionindustry homeowners, propertymanagers,tenants,and to moldgrowthinhomeshavemade increase incomplaintsandlegalactionrelated The expenseofmoisturerepairsandthe preventing them. the moistureproblemslistedaboveinsteadof U.S., thisprescriptiontypicallycontributesto control. However, inthehumidsoutheastern means forprovidingcrawlspacemoisture passive ventilationwithoutsideairasthe and conventionalwisdomhaveprescribed Since the1940s,residentialbuildingcodes and sub-contractors. crawl spacedesignsbycodeofficials to helpyougainacceptanceofyour closed code developmentandfieldresearch isoffered alternatives. Thebackgroundinformationon tips aboutpitfallstoavoidandavailable implementation ofclosedcrawlspaces,with guidance towardsgooddesignand we hopethisreferenceprovideseffective For buildersandclosedcrawlspaceinstallers, the residentialconstructionindustry. information toabroadrangeofstakeholdersin This guideisintendedtoprovideuseful Audience • Drainsorpumpsremovewatercomingfrom systemsprovide • Mechanicaldrying • Vapor retardersminimizetheevaporationof ofhumid • Airsealedwallsminimizetheentry • Exteriorwatermanagementprevents water sourcesthataffectcrawlspaces: system workintandemtocontrolthevarietyof The keycomponentsofaclosedcrawlspace crawl space. potential forcondensationonsurfacesinthe the 70%targetanddramaticallyreduce plumbing leaksorfloods ongoing, activeremovalofwatervapor water fromthegroundorperimeterwall outside air intrusion ofliquidwater I NTRODUCTION An Introduction for the Southeast 3 ORG . CRAWLSPACES . WWW anticipate that the performance

primarily in low-volume construction of closed low-volume construction primarily in simple in small homes with crawl spaces more plans. Builders of the foundation mainstream typically found in complex homes will likely need to residential construction process, adjust the sample construction in high volume. Future especially if they build will focus Advanced Energy research specifically on the delivery of closed crawl builder environment. spaces in the production We closed crawl spaces in improvements seen in will translate verythe Princeville project well to similar homes throughout the southeastern U.S. Future Advanced Energy research will also property owner, or other contractor planning to or other contractor property owner, you to crawl spaces, we invite install closed to your designs and processes adjust these home code requirements, local site conditions, and occupant design, construction processes Remember that needs to ensure success. the same closed crawl spaces share types or vulnerability of other foundation components: Just like residential water control and roof flashings, basements, slabs, window or plumbing, a foundation waterproofing is installed improperly closed crawl space that good. can do more harm than Please note that the sample designs and processes discussed here have been tested A view of the homes in the Princeville research project. Six homes are located on each side of A view of the homes in the Princeville research project. Six homes are located on each the same street. Using this Guide The closed crawl space designs and processes presented in this guide are not the only ones that are acceptable. They are simply examples that have performed successfully in Advanced Energy field testing or in projects by professional installers in North Carolina. There are many other closed crawl space designs that can perform acceptably and that meet the requirements of the North Carolina residential of building code. As we verify the performance additional designs and techniques we hope to add them to this reference, along with updated information gained from long-term monitoring. It is important to keep in mind that the designs and techniques presented in this guide are not definitive specifications. If you are a builder, For code officials, we hope that the discussion we hope that the For code officials, of the and components on the development a residential code provides North Carolina available understanding the newly resource for of North Carolina, we code language. Outside a resource for the offer this information as of similar code development and adoption of other regions. language to meet the needs private home For property owners and this guide provides inspectors, we hope that existing wall-vented knowledge for assessing as well as tools for or closed crawl spaces new closed specifying and purchasing crawl spaces. NTRODUCTION I H

4 Closed Crawl Spaces IGH -P ERFORMANCE T humidity, anddewpoint temperature. three propertiesofair:temperature, relative To contributing watervaportothecrawlspace. space. thecrawl seasons, andhasnopotentialtodry air inthecrawlspaceduringwarm outside aircontainsmorewatervaporthanthe investigations ofcrawlspacefailure: repeatedly inpreviousshort-term other buildingscientistshavemeasured confirmed overthelongtermwhatweand the crawlspace.AdvancedEnergyresearchhas intentionally movemoreoutsideairthrough or byinstallingafanmultiplefansto additional ventilationopeningstotheoutside add moreventilation,eitherintheformof typical “cure”forsuchproblemshasbeento wood moisturecontent,orrot.The like condensation,surfacemoldgrowth,high spaces routinelyexperiencemoistureproblems with outsideair. However, wall-ventedcrawl crawl spacesistoprovidepassiveventilation traditional methodofcontrollingmoisturein outasoutheasterncrawlspace?The air dry Why doesn’tventilationwithoutsidesummer The Ventilation Myth different climates. in energy useinhomesofdifferentgeometry similar improvementsformoisturecontroland confirm whetherclosedcrawlspacesdeliver emperature isthemostfamiliarproperty, and

understand why, first weneedtodefine Instead, theoutsideairendsup H OMES the into liquidwater, eitherbecausetheaircools which thewatervaporinairwill condense measurement tellsyouthetemperature at changes. Asyoumightguess,thedewpoint goes upwhetherornottheairtemperature changes. Ifyouaddwatervapor, thedewpoint down whetherornottheairtemperature you removewatervapor, thedewpointgoes water vapor, thedewpointstayssame.If temperature ofairwithoutaddingorremoving water vaporisintheair. Ifyouchangethe point,” isamoredirectindicationofhowmuch Dew pointtemperature,oftenjustcalled“dew humidity increases. cooler withoutlosingwatervapor, itsrelative less watervaporthanwarmair, soifairgets know theairtemperatures.Coldcanhold location hasmorewatervaporunlessyoualso another locationis40%,youcan’ttellwhich location is90%andtherelativehumidityin the airchanges.Ifrelativehumidityinone vapor intheairchangesortemperatureof humidity changesifeithertheamountofwater the currenttemperature.So,relative water vaporthattheaircanpossiblyholdat vapor intheairtomaximumamountof Relative humidityistheratioofactualwater better knowntousas“condensation”or“rain”. water vaporcondensesintoliquidwater… water vaporthataircancontainbeforethe temperature, thereisalsoalimittohowmuch certain amountofwatervapor. Atthecurrent At anymoment,theairaroundyoucontainsa what exactlyisrelativehumidity? is simplyameasureoftheheatinair. But otmsd fteislto r eo 0 F, so bottom sideoftheinsulationarebelow 70° temperature oftheductwork,plumbing, and it’s awhopping90%! Furthermore,the chart tofindthenewrelativehumidity…andnow dropped, soweneedtousethepsychrometric F. Thetemperature has dew pointstaysat70° down. Nowatervaporhasbeenremoved,sothe C),sotheoutsideaircools F(23° space is73° summertime temperatureinawall-ventedcrawl that airgoesintothecrawlspace.Atypical compared totypicalconditions.Nowlet’s assume C),which isrelativelydry F(21° is 70° chart, wedeterminethatthedewpointofthisair for ventilatingacrawlspace.Usingslideruleor that thisairiswarmanddry, soitshouldbegreat humidity is60%.Conventionalwisdomtellsus C)outsideandtherelative F(29° say it’s 85° on amildsummerdayinNorthCarolina.Let’s As anexample,let’s lookatthepropertiesofair Ame of theACCA(AirConditioningContractors Internet. We haveprovidedasimplified several on-linepsychrometriccalculatorsonthe dehumidification equipment,andthereare manufacturers ofairconditioningor psychrometric chartorsliderulefrom changed. You cangenerallyobtaina change inonepropertyifanotheris humidity areknown.Theycancalculatethe dew pointwhentheairtemperatureandrelative you knowtheothertwo,forexample,calculating to calculatetheunknownthirdpropertyofairif Psychrometric chartsandsliderulesallowyou cooler thanitsdewpointtemperature. the aircomesintocontactwithasurfacethatis down tothedewpointtemperature,orbecause ri ca) psychrometric chartinAppendixB. version I NTRODUCTION An Introduction for the Southeast 5 ORG . CRAWLSPACES . WWW After installation of a powered crawl space After installation of a ventilation fan, so much water condensed on the floor joists that rot set in and destroyed the lower portion of the joists.

This data from the Princeville site shows that for most of a very humid 48-hour period, the outside dew point exceeds 74° F (24° C) and is higher than the temperature inside the crawl space. If this outside air enters the crawl space, the water vapor will condense on surfaces inside. Note that this was not a period of very rainy weather; records indicate only 0.2 inches of rainfall over this entire 48-hour period.

° C) ( Temperature 25 24 23 22 After noticing light mold growth on floor After noticing light mold joists in a wall-vented crawl space, a contractor recommended installation of a powered crawl space ventilation fan to “dry” the crawl space. Vented Crawlspace Temperature Outside Dew Point Outside Air Dew Point and Vented Crawlspace Temperature

72 74 76 78

° F) ( Temperature Aug 8 '03 12 AM Aug 8 '03 12 PM Aug 9 '03 12 AM Aug 9 '03 12 PM Aug 10 '03 12 AM the water vapor will condense on those surfaces. will condense on those the water vapor space floor or condense on the crawl It may even ventilating framing! It turns out that on the wood the crawl air adds moisture to with the outside space, it does not dry it out. in central and Summer moisture conditions often much wetter than eastern North Carolina are drought the example. In the record-setting air dew point summer of 2002, the outside exceeded 70° F 44% of the time at Advanced Princeville research site. In the record- Energy’s the outside air dew setting rainfall year of 2003, point exceeded 70° and F 72% of the summer inside the crawl was higher than the temperature space almost 20% of the summer. NTRODUCTION I H

6 Closed Crawl Spaces IGH -P ERFORMANCE H OMES An Introduction for the Southeast 7 ORG . CRAWLSPACES . WWW 1. Blocking sources 2. Facilitating removal have chosen not to present the components

Note that moisture management during the Note that moisture management construction process involves several additional measures which are described in the sample construction sequence in Section 3. We of moisture management in the order used by we the North Carolina residential code. Instead, present them in order of components located outside the crawl space to components located inside the crawl space, since this follows the model of first blocking sources and then facilitating removal. Moisture Management Moisture crawl of the finished Moisture management space is the primary goal of any closed crawl components both space system, and it involves crawl space. Moisture outside and inside the liquid water and water management, for both uses two basic strategies: vapor, component that will provide an extra level A gold star indicates an optional of performance or safety that is required by the North Carolina A red check mark indicates a component residential code A green plus sign indicates a component that is recommended by Advanced Energy The dozens of individual components that of individual components The dozens closed crawl and effective make up a complete categories of fall into six general space system function: • Moisture management • Pest control • Combustion safety • Thermal insulation • Fire safety • Radon safety each categoryThis section discusses with and then specific background information components. The list of categories follows the order of requirements in the North Carolina residential code. Several specific items, like foundation drainage or foam plastic fire safety, are not in the crawl space code section but are included here in the interest of completeness. This section uses three symbols to indicate different levels of components: ✱ ✔ ✚ OMPONENTS C ESIGN D ECOMMENDED ESIGN OMPONENTS Overview variety of design This section presents a or exceed the minimum components that meet requirements for closed crawl spaces, as specified by the North Carolina residential code discussed in Section 4. The recommended design components presented here are not the only ones that are acceptable. They are simply examples that performed successfully in the field testing detailed in Section 6, in other Advanced Energy research projects or by professional installers in a variety of locations in North Carolina. There are many other closed crawl space designs that can perform acceptably and that meet the requirements of the North Carolina residential building code. The design components presented here are not definitive specifications. If you are a builder, or other contractor planning to property owner, install closed crawl spaces, you will need to adjust these design components to your local site conditions, code requirements, home design, construction processes and occupant needs to ensure success. R D C Section 1 Section ECOMMENDED R H

8 Closed Crawl Spaces IGH -P ERFORMANCE Exterior groundandsurfacewater Roof runoff Blocking Sources Moisture Management: ✔ ✔ ✚ grade forapproximately6feet. away fromthefoundationwallbelow like EPDMrubberthatextendsdownand example, alayerofimpermeablematerial option isfoundation“flashing,”for perimeter gravelbedandadrain.Another system offoundationwaterproofing, often aguttersystem,butcouldalsobe from enteringthecrawlspace.Thisis from thehouseandpreventrunoff Use asystemtodirectroofrunoffaway roof runofftoenterthecrawlspace. that blockagesorheavyrainswillcause space drain.Thiseliminatesthechance they mustnotbeconnectedtothecrawl leaders areusedtomanageroofrunoff, If sub-surfacedrainpipesorgutter barriers prohibittherequiredgrading. used iflotlines,slopes,walls,or other from thehouse.Swalesordrains may be run todirectgroundsurfacewater away (152 mm)offallover10feet(3048 of thehousewithaminimum6inches Provide sitegradingaroundtheperimeter H OMES ✚ ✔ ✔ of water entry inheavyrainsorminorflooding. of waterentry The entrancetothisclosedcrawlspace iselevatedwellaboveexteriorgrade,reducingthelikelihood water-proofing whentheexteriorgradeis Provide foundationdamp-proofingor crawl spacedrainsystems. foundation drainsystemsseparatefrom more aboveinteriorcrawlspacegrade.Keep the exteriorgradeis12inches(305mm)or Provide afoundationdrainsystemwhenever the crawlspacewalls. sure thesesystemsdonotputwateronto problem inanadjacentcrawlspace.Make because theycaneasilycauseawater yard sprinklersrequirespecialattention the house.In-groundirrigationsystemsor features thatpreventdrainageawayfrom mounds, mulchpilesorotherlandscaping owners donotinstallflowerbeds,tree Ensure thatlandscapersorproperty Photo credit:IndoorEnvironmentalSystems. R ✚ ✚ ECOMMENDED by capillary actionor“wicking.” by capillary prevent theflowofwaterthroughwall above theinteriorcrawlspacegradeto communities, to access doors,especiallyincoastal prevent waterentry. Usenon-corroding possible, provideadamorgraveldrainto exterior grade.Ifraisedaccessisnot least 4inches(102mm)higherthanthe possible, buildthebottomofaccessat door onagableendwall.Whenever no roofrunoffsystem,locatetheaccess from roofrunoff.Forexample,ifthereis Protect exteriorcrawlspaceaccessdoor(s) drain, damp-proofingorwater-proofing. grade toeliminatetheneedforafoundation R aise thecrawlspacegradeaboveexterior prevent

D deterioration. ESIGN C OMPONENTS An Introduction for the Southeast 9 ORG . CRAWLSPACES . Photo credit: Healthy Home Environment. … there are typically large gaps in the perimeter wall around and between the supply and return ducts. These gaps require solid backing materials and sealants for proper air-sealing. Remove any rubble underneath the opening to reduce the risk of damage to the ground vapor retarder. Seal all penetrations in the perimeter wall. Photo credit: Indoor Environmental Systems. When you see packaged unit When you see packaged of the equipment on the outside crawl space… Photo credit: Healthy Home Environment. WWW Seal connections from the crawl space to from the crawl space Seal connections attached porches or decks, areas under water sites of liquid which are common intrusion or entry of humid outside air. to flooding or Houses in an area prone Flood Hazard Area designated as a Special Emergency (SFHA) by the Federal or the Management Agency (FEMA) Program (NFIP) National Flood Insurance flood must have FEMA/NFIP-compliant perimeter wall. vents in the crawl space more sidebar for See the “Flood Vents” information. ✔ ✔ OMPONENTS C ESIGN D Seal all gaps between foundation wall and between foundation Seal all gaps and plate and band joist, sill plate, sill Seal penetrations band joist and subfloor. wall for water through the crawl space service, service, electrical plumbing Use solid blocking fixtures, ductwork, etc. between the and sealants to seal gaps ductwork for exterior wall opening and heating and outdoor packaged-unit cooling equipment, if present. Photo credit: Building Performance Specialists. This foundation wall has an effective gasket between the sill and the masonryThis foundation wall has an effective gasket wall, but band joist or between the band joist and the small gaps between the sill plate and the subfloor add up to large leak areas. Close these joints with gaskets or sealants as well. ✔ Humid Air ECOMMENDED R H 10 Closed Crawl Spaces IGH -P ERFORMANCE ✚ ✚ To International Codesmeettheserequirements. must beimplemented.The2000(andlater) vents aswelltheguidelinesforwherethey specify thedesignrequirementsforflood and theNationalFloodInsuranceProgram The FederalEmergencyManagementAgency leakage asmuchpossible. flood ventmodelthatreducesstandbyair required inaclosedcrawlspace,choose forces onthefoundationwalls.When foundation inordertoequalizehydrostatic passage offloodwaterintoandouta wall thatautomaticallyallowthefree Flood ventsareopeningsinafoundation Flood Vents can jeopardizeacommunity’s abilityto Non-compliance withfloodventrequirements be made. be requiredbeforeafinaldeterminationcan andelevationcertificate may property survey department orgoverningauthority. A contact yourlocalbuildinginspections be requiredtohavefloodventsinstalled, Special FloodHazardArea(SFHA)andwill walls witheitheracontinuoustopcourse foundation Build hollow-blockmasonry minimize stand-byairleakage. When required,choosefloodventsthat

determine ifapropertyislocatedin H OMES Photo credit:HazardMitigationContractors, Inc. central panelisinsulatedwithfoam. reduce stand-byairinfiltrationand the This floodventhasaweatherstrip to floodplain management. division ofemergencymanagementor 800-480-2520) orcontactyourstate’s available fromFEMA(www.fema.gov, or Bulletin 1-93,OpeningsinFoundationWalls, For additionalinformation,refertoTechnical with floodventrequirements. a houseissoldifthedoesnotcomply when insurancepoliciesarerenewedor insurance premiumsmaygoupsignificantly more. Fortheindividualhomeowner, assistance, construction,propertyloans,and range offederalfundsforemergency participate intheNFIPortoreceiveawide crawl space. of airfromtheinteriorwallinto groutedsolidtopreventpassage masonry orthetopcourseof of solidmasonry crawl space! Do notleaveanyexposedearthinthe R perimeter walls Evaporation fromthegroundand ✚ ✔ ECOMMENDED wall insulation. vapor retarderupbehindafurringstripor screwsthatholdthe pins ormasonry attachment includepowder-driven nails, mastic. Commonstrategiesformechanical material andsealittothewallwithduct Mechanically attachthevaporretarder atthetopof wall. of exposedmasonry retarder, leavingatleast3inches(76mm) minimum 6-milpolyethylenevapor perimeterwalls with Cover themasonry (305 mm). retarder. Lapseamsatleast12inches minimum 6-milpolyethylenevapor Cover allcrawlspacegroundwitha Photo credit:BillWarren. D ESIGN C OMPONENTS An Introduction for the Southeast 11 ORG . B CRAWLSPACES . WWW A The ground vapor retarder must be secured to resist movement or tears. If you use unreinforced 6-mil polyethylene (the material most commonly available at home improvement retail stores), protect it with an additional layer of durable material (for example, artificial turf, vinyl runners, or other carpet material) in storage areas or traffic areas, like a serviceto path mechanical equipment. Consider using reinforced vapor retarder materials thicker, for improved durability and puncture resistance, and to eliminate the need for additional protective coverings. ✔ ✚ Overlap seams in the vapor retarder material to reduce the Overlap seams in the vapor retarder material the wall or ground chance that liquid water running downhill from seams. Lap the will collect against the underside of the sealed retarder (A) and ground vapor retarder on top of the wall vapor sections of lap downhill sections of vapor retarder over uphill vapor retarder (B). Seal the ground vapor retarder to interior vapor retarder to Seal the ground above least 4 inches (102 mm) columns at floor. the crawl space wall vapor retarders Install the ground and all seams and as a sealed liner by sealing connections to masonry with fiberglass duct mastic. If you mesh tape embedded in to seal choose to use a tape product surfaces are clean seams, ensure that all and do not subject before applying the tape stress. Both of tape joints to mechanical tape joints to these situations have caused research houses. fail in Advanced Energy apor retarder material is attached with a ✚ ✚ V furring strip three inches (76 mm) below the top of the masonry wall and sealed to the wall is with mastic. The wall vapor retarder material a sealed to the ground vapor retarder to form dryer Penetrations, like the continuous liner. vent in the photo, are completely air sealed. The top of the masonry front edge wall and the of the sill plate have been painted white with mastic to improve inspectability by pest management professionals. OMPONENTS C Photo credit: Bill Warren. ESIGN D One way to mechanically attach a wall One way to mechanically it behind a vapor retarder: secure preservative-treated plywood furring strip attached to the masonry with nails driven through washers. This heavy-duty vapor retarder material is mechanically supported by metal pins with cap washers and sealed to the masonry with fiberglass mesh tape and duct mastic. Photo credit: Indoor Environmental Systems. ECOMMENDED R H 12 Closed Crawl Spaces IGH -P ERFORMANCE additional moistureload. is capableofremovingtheresulting mechanism acceptably iftheinstalleddrying exposed. Suchasystemcanstillperform increases thechancethatgroundwillbe seams ofthegroundvaporretarder warm weather. Choosingnottosealthe moisture enteringthecrawlspaceduring perimeter wallswilltypicallyresultinmore Choosing tonotuseavaporretarderonthe soil gasesintothecrawlspace. be improvedresistancetothemovementof it lesslikely. Anotherunintendedbenefitmay liquid waterfromtheground,butitwillmake liner isnotdesignedtopreventintrusionof plumbing leakwillbediscovered.Thesealed makes itmorelikelythatawaterfailurelike people movearoundinthecrawlspace,and material reducestheriskofdamagewhen Sealing theseamsofvaporretarder effective crawlspacemoisturemanagement. design aspartofasystemthatprovided ground becausewehavefieldtestedthis sealed vaporretardercoveringthewallsand Advanced Energyrecommendstheuseofa retarder asasealedliner? recommend installingthevapor Why doesAdvancedEnergy ✚ polyethylene withsodstaplesor anticipated traffic.Anchor6-mil toresistmovementdue as necessary Secure thegroundvaporretarder material H OMES moisture management. mechanism isrequiredtoensure adequate crawl space,butanintentionaldrying potentialforaclosed may providesomedrying diffusion ofwatervaportothehouseabove water andvapor. Ductleakageand needs componentsthatremovebothliquid For allthesereasons,aclosedcrawlspace the crawlspace. Plumbing failuresorfloodsputliquidwaterin impossible todoaperfectair-sealing job. humid airthroughtheperimeterwall,sinceit’s pressures willinevitablyforcesomeamountof space. Wind,ductleakageorotherbuilding wall orsillplateandevaporateintothecrawl Rain canwickthroughtheperimetermasonry columns andevaporateintothecrawlspace. wallsorsupport can wickupthroughmasonry properly closedcrawlspace.Groundmoisture Please rememberthatmoisturestillgetsintoa Facilitating Removal Moisture Management: not needanystaplesorspikes. crawl spaceswithintermediatepiersmay materials insmallcrawlspacesorlarge paths.Heaviervaporretarder service areas likethecrawlspaceentranceor steeply slopedareasorinheavytraffic or spikestosecurethevaporretarderin (3658 mm)centers.Useadditionalstaples nailing tinsonapproximately12foot galvanized spikesthroughwashersor Photo credit:IndoorEnvironmentalSystems. assembly isreadyforinstallation. This crawlspacedrainandbackflow valve R equipment forthehome. crawl spaceonthesizingofmechanical writing tocalculatetheimpactofaclosed commonly availabletoolsatthetimeofthis and coolingequipment.However, therearefew contractor todown-sizetheinstalledheating closed crawlspacesallowthemechanical that themoisturecontrolimprovementsof Some installersandresearchershavetheorized ✚ ✔ ECOMMENDED and poseariskofsewagebackup. of sewergasesif(when)thetrapdriesout municipal sewersystemmayallowentry house plumbingwastedrainortoa with p-trapsthatconnecttothewhole- the chanceofverminentry. Floordrains water intothecrawlspaceandtoreduce pipes topreventreverseflowofoutside and acheckvalveinsumppumpout-flow Use abackflowvalveincrawlspacedrains plumbing leakorotherfloodingevent. water fromthecrawlspaceincaseofa pump ateachlowpointtoremoveliquid more lowpoints.Provideadrainorsump Grade thefloorofcrawlspacetooneor D ESIGN C OMPONENTS An Introduction for the Southeast 13 ORG . CRAWLSPACES . WWW rminate all kitchen and bathroom rminate clothes dryer exhaust vents significantly inside the crawl space before inside the crawl space significantly out. they can drain or humidity monitors Include relative the design to liquid water detectors in performance of inform occupants of the the system. Te exhaust vents to outside. Install auxiliary condensate drain pans under air handlers with float kill-switches crawl space or dehumidifiers in a closed overflows due for added security against line. to blockage in the condensate Te to outside. subterranean termites or other insect pests professionals to inspect the structure and provide treatment, when necessary. wo important goals of a closed crawl space ✱ ✔ ✚ ✚ Pest Control T design are to increasing the risk of damage from Avoid 1. 2. Provide the ability for pest management Under North Carolina structural pest control regulations, pest management professionals are not liable for infestations or damage already present in hidden or obstructed areas rminate appliance water discharge pipes rminate crawl space drains or sump rminate crawl Provide a mechanical drying system to Six methods are remove water vapor. residential code allowed under the NC See the next item discussed in Section 4. for recommended strategies. Te (for example, water heater temperature/pressure relief valves, air conditioner or dehumidifier condensate drains, or water softener discharges) to outside, to an interior pump, or to a crawl space drain. Te the in ways that reduce pump discharges or blockage. For example, risk of damage or termination with gravel surround the shrubbery reduce the risk of soil to lawn equipment. blockage or damage from the supply-side Use conditioned air from dehumidifiers to ductwork or stand-alone meet the requirement for a mechanical drying field system. Advanced Energy has tested both of these methods. See Section 3, Sample Designs and Construction Process, for a detailed description of these two drying of mechanisms and discussion advantages and disadvantages for each. Drain appliance discharge pipes directly to outside or to an interior pump, not to crawl space drains. If the backflow valve in the crawl space drain is installed out of level or if there is water in the drain pipe exerting pressure on the backflow valve, appliance discharges may build up ✚ ✔ ✚ ✔ ✚ OMPONENTS C ESIGN D Photo credit: Indoor Environmental Systems. Use sump pumps if desired or when gravity drains are not feasible. This model includes a cap for the housing and an optional liquid water alarm to detect a failure of the sump pump system. The finished ground vapor retarder is The finished ground vapor drain opening. sealed directly to the Systems. Photo credit: Indoor Environmental ECOMMENDED R H 14 Closed Crawl Spaces IGH -P ERFORMANCE because thispreventsinspection. band joistorsillplatetothecrawlspacefloor insulation orvaporretardermaterialsfromthe the structure.Itisnotacceptabletodrape for wood-destroyinginsectsfromthegroundto perimeter walls,sincethisisacommonpath particular attentiontomaterialsappliedonthe Closed crawlspacedesignsmustpay inspections ortreatments. access forthepre-treatmentorfuture design tobelievethattheywillhaveadequate information abouttheclosedcrawlspace treatment unlesstheyhavesufficient treatment, oranalternativepre-construction to providesoilpre-treatment,woodpre- pest managementcontractorsmaybereluctant obstructed areas.Innewconstructionprojects, contracting onpropertieswithhiddenor their treatment.Thisdiscouragesthemfrom that occurstothepropertyafterdateof be heldresponsibleforanyandalldamage warranty, thepestmanagementcontractormay contractor For propertiesunderaservice building toallowforinspection. tools orremovalofpiecespartsthe building thatwouldrequiredisassemblywith of “hiddenorobstructed”includesareasthe areas ontheinspectionreport.Thedefinition transactions iftheprofessionalidentifiessuch when theyperforminspectionsforrealestate H OMES Photo credit: Building Performance Specialists. Photo credit:BuildingPerformance andwood. interface ofmasonry maintain thetermiteinspectiongapatevery careful detailingatallbeampocketsto This crawlspaceunderconstructionhas ✔ ✔ space floorsurface. perimeter wallinsulationandthecrawl least 3inchesbetweenthebottomofany Provide aclearanceorwickinggapofat wood framing. insulation materialsmustnotcontactany wall.Vaporperimeter masonry retarderor wall insulationandthetopof vapor retardermaterialand/orperimeter least 3inchesbetweenthetopofanywall Provide atermiteinspectiongapofat R ✔ ECOMMENDED ❍ ❍ also beinsulated. space isinsulated,thebandjoistmust When theperimeterwallofaclosedcrawl need tobefire-ratedfordirectexposure. band iscold.Thefacingmaterialmay condensation onthebandwhen may increasethechanceof space duringthecoolingseason,but ofthebandjoisttocrawl drying damage. Thisstrategyallowssome removed andreplacedwithout professional sinceitismoreeasily treatment byapestmanagement space, facilitatesinspectionor facing towardstheinsideofcrawl batt insulation,withthevaporretarder Insulating thebandjoistwithfaced on thebandwheniscold. reduce thepotentialforcondensation tothecrawlspace,butwouldalso dry will reducetheabilityofbandto (< 1perm)permeabilitytowatervapor condition. Foaminsulationswithlow or impossibletoreplaceinitsoriginal foam maybedamagedintheprocess management professional,becausethe “sounding”) ofthebandbyapest physical inspection(“probing”or joist willseriouslyimpairvisualor The useofrigidfoamontheband D ESIGN C OMPONENTS An Introduction for the Southeast 15 ORG . CRAWLSPACES . WWW Advanced Energy recommends the use of carbon monoxide low-level monitors or alarms in any home (including homes with slab or basement foundations) that has an attached garage or any fuel-fired water cook stove, furnace, boiler, fireplace, or other appliance. heater, For additional protection, consider using a fuel-gas alarm when there are gas-fired appliances or gas lines in a home. These alarms can detect leaks of propane or natural gas and alert occupants to the problem. ✚ ✱ General Combustion Safety General has of whether or not a home Regardless a closed crawl space foundation, serious issue. combustion safety is a Over 200 people die every year in the (CO) U.S. from carbon monoxide combustion poisoning due to faulty Thousands of appliances in the home. room treatment people require emergency of CO, and for exposure to high levels to researchers are still working serious effects understand the potentially of chronic low-level exposure to CO. openings is not acceptable because it not acceptable because openings is requirements for air-sealing violates the floor wall around and the the perimeter crawl space. above the closed Specify direct-vent (“two-pipe”) models to Specify direct-vent (“two-pipe”) air when ensure adequate combustion used. All air for fuel-fired appliances are piped directly from combustion should be and all outside into the appliance should be combustion exhaust gases appliance to piped directly from the have outside. Some manufacturers that can separate cabinets or enclosures be used to convert non-direct-vent appliances to direct-vent operation. ✚ Photo credit: Bill Warren. The two large PVC pipes entering this direct-vent furnace bring combustion air from outside and take exhaust gases to outside to ensure that the furnace will not backdraft or burn inefficiently in the presence of negative building pressures. OMPONENTS C ESIGN D Fuel-burning appliances located in a closed crawl space shall obtain combustion air from outdoors per the North Carolina Mechanical Code. Note that the use of passive combustion air Atmospheric or “natural” draft appliances should not be installed in a closed crawl space. volume or openings to the outside per volume or openings to mechanical code requirements, carbon monoxide, or created by duct leakage or stack effect. ✔ ✚ Gas- or oil-fired appliances, such as furnaces, appliances, such Gas- or oil-fired need combustion air. water heaters, or boilers, the air, Without sufficient combustion carbon monoxide or fail appliance can produce Advanced Energy has to draft properly. cases in which documented numerous in wall-vented combustion equipment crawl spaces sufficient combustion air did not have 1. generated unacceptably high levels of 2. did not draft acceptably due to air pressures 3. closed crawl space is A properly air-sealed much tighter than a wall vented crawl space and a can even be tighter than the house above. As result, Advanced Energy recommends that: Combustion Safety Combustion ECOMMENDED R H 16 Closed Crawl Spaces IGH -P ERFORMANCE with floorinsulationincentralNorthCarolina. similarly outperformwall-ventedcrawlspaces spaces witheitherfloororwallinsulation results inSection6showedthatclosedcrawl located attheperimeterwallonly. Theresearch insulation inan“unvented”crawlspacetobe International ResidentialCode,whichrequires conflicts withthe2004Supplementto at thesub-floororperimeterwall.This insulation inaclosedcrawlspacetobelocated The NorthCarolinaresidentialcodeallows Thermal Insulation ✔ ✔ ✚ ✔ reduces theriskofcontamination orother of theperimeterwallisinsulated. This closed-cell foaminsulation)ifthe inside Use non-porousinsulation(forexample,a inches orless. wallheights of9 insulation onmasonry as a“ponywall”)donotrequire framed portioniscommonlyreferredto and partiallywoodframed(the Perimeter wallsthatarepartiallymasonry on optionsforbandjoistinsulation. joist. See“PestControl”abovefornotes insulation mustbeinstalledontheband If theperimeterwallisinsulated,then provide therequiredR-value. wall, ortheperimeterwallitselfmay exterior surfaceorinsideoftheperimeter on anycombinationoftheinteriorsurface, Perimeter wallinsulationmaybelocated H OMES or theycanacceleratethespread of afireif release toxicorflammablegases when heated, some foaminsulationshavethepotential to scrutiny inresidentialbuildingcodes because Foam plasticinsulationreceivesspecial materials forfireblockingincrawlspaces. requirements torequiretheuseofnon-porous insulation. NorthCarolinahasimprovedthese porous materialslikefiberglassorrockwool residential buildingcode,butallowtheuseof Fireblocking requirementsalreadyexistinthe fireblocking betweendifferentlevelsinahome. A keyelementinresidentialfiresafetyis Fire Safety ✚ I-beam floorstructures. insulation performanceinwooden strategies wouldlikelyalsoimprove cavity withblowninsulation.These of thetrussesandcompletelyfilling using sprayfoamornettingthebottom open-web floortrusssystemsinclude structure. Betteroptionsforinsulating insulating theopeningsintruss discouraged duetothedifficultyin truss systemswithbattinsulationis R-value. Insulatingopen-webfloor with thesub-floortoachievenominal gaps orcompressionandinfullcontact Install insulationatthesub-floorwithout leak orflood. damage totheinsulationifthereisawater R documentation. ignition barrierwiththeappropriate can beinstalledwithoutathermalbarrieror reduce oreliminatethoserisks.Suchproducts products havebeendesignedandtestedto insulation. However, severalfoaminsulation gypsum boardorequivalent)overfoam ignition barrier(typically3/8inch[10mm] [13 mm]gypsumboardorequivalent)an require athermalbarrier(typically1/2inch they ignite.To reducetheserisks,mostcodes ✚ ✔ ✔ ✔ ECOMMENDED materials thatpresentafirehazard. gasoline, solvents,oranytools Do notuseacrawlspacetostore joist orponywalls,ifapplicable materials onbattinsulationintheband allow installationofexposedfacing Provide documentationoffire-ratingto barrier oranignitionbarrier, ifapplicable exposed foaminsulationwithoutathermal the product)toallowinstallationof National EvaluationReport(ICCNER)for ratings (intheInternationalCodeCouncil Provide documentationofproductfire- is notsufficient. wool orfiberglassinsulationalone with non-porousmaterials.Rock penetrations throughthesubfloor plenum, gaslineandotherwiring Seal allplumbing,electrical,duct, D ESIGN C OMPONENTS An Introduction for the Southeast 17 ORG . CRAWLSPACES . WWW rate of moisture entry. So for example, if you So for example, if entry. rate of moisture then retarder, to install a wall vapor choose not ensure that the dryingyou need to mechanism the desired is sufficient to provide you install despite the extra moisture management perimeter walls. moisture load of the exposed and error approach This may require a trial available tools to since there are no readily moisture loads and size accurately predict such the drying mechanism. these recommendations represent Altogether, that have closed crawl space components in real-world field proven their performance tests. They perform as a system, and although obvious that some components, like it’s preventing water intrusion, are critical, we have not experimented to determine which of the other components could be sacrificed without compromising the system as a whole. It is important to keep in mind that these sample design elements were tested in small homes with very plans. To simple foundation ensure success, builders of the more complex homes typically found in mainstream residential construction will likely need to adjust the designs to accommodate local site conditions, code requirements, home design, construction processes and occupant needs. ou might be wondering “Do I really need to system are compatible with the requirements of compatible with the requirements system are Sub-slab or sub-membrane Appendix F. utilized in a systems may be depressurization as in a space in the same manner closed crawl crawl space slab, basement or wall-vented may require foundation. Local jurisdictions the ground substrate, additional measures for joints, condensate foundation wall, concrete wall-vented or closed drains, or sump pits in crawl spaces. Summary The dozens of individual components that make up a complete and effective closed crawl of space system fall into six general categories function: • Moisture management • Pest control • Combustion safety • Thermal insulation • Fire safety • Radon safety Y follow all of the recommendations in this section to have a closed crawl space that works?” The short answer is “no.” There are other designs that will perform successfully. The key for acceptable moisture management is that the rate of moisture removal from the crawl space must be at least as much as the OMPONENTS C ESIGN D Radon is an odorless, colorless gas that is the odorless, colorless gas Radon is an cause of lung cancer in second most common in over 20,000 the United States, resulting U.S. An estimated 1 in 15 deaths per year. of radon. For these homes has a high level General and the reasons, the U.S. Surgeon Agency (EPA) Environmental Protection be tested for radon. recommend that all homes radon-resistant For jurisdictions where radon control construction is required, in Appendix F of the methods are specified AF101(1) International Residential Code. Table lists the counties identified by the as Environmental Protection Agency (EPA) High Radon Potential (Zone 1) counties. The High Radon Potential designation indicates 4 areas with expected radon concentrations of where it pCi/L (picocuries per liter) or greater, is likely that radon-resistant construction will be required. recommends that all homes with The EPA be radon concentrations of 4 pCi/L and greater also recommends that the mitigated. The EPA county listing be supplemented with other available state and local data, for example, data from state radon offices, public health agencies or cooperative extension services, to further understand the radon potential of Zone 1 areas. When radon mitigation is required, the requirements for floor sealing, duct sealing, access door air sealing, ground vapor retarder, and damp proofing of a closed crawl space Radon Safety Radon ECOMMENDED R H 18 Closed Crawl Spaces IGH -P ERFORMANCE H OMES An Introduction for the Southeast 19 ORG . CRAWLSPACES . WWW of a quality installer can be well worth the additional expense. Finding a quality installer typically requires in identifying providers of closed crawl spaces your area and then getting proposals from several an providers for the specific job at hand to make apples-to-apples comparison. Ideally you would look at previous work and talk with previous performance. clients to assess the provider’s of Assess the knowledge, experience and integrity the provider with regard to the seven implementation topics described in this section. a The potential benefits and risks of installing closed crawl space demand that the work is performed the right way at the right time. of Advanced Energy recommends that you think in the closed crawl space installer as a partner moisture management, not as just another “sub” on the project. ou or your installer may prefer one closed ou or your installer may A seventh topic applies when you hire applies when you A seventh topic an installer: pricing. a clear contract and • Establishing Defining the Design Defining the Y others, but should also crawl space design to choice of materials or be able to customize the drying to suit the needs of the mechanism residential code house design or local like site conditions, requirements. Factors Finding a Quality Installer More and more businesses are offering the you service of closing crawl spaces. Currently, could purchase a closed crawl space in central North Carolina from: • Home performance contractors • Pest management contractors • General contractors • Professional engineers contractors • Mechanical (HVAC) • Insulation contractors • Foundation repair/waterproofing contractors Although hiring an installer to provide a closed than crawl space may be more expensive up front doing it yourself, the knowledge and experience the work. In some regions, owners and some regions, owners the work. In themselves have to do the work builders may installers. of local experienced due to a lack implementation Advanced Energy divides topics: guidelines into six broad • Defining the design with code officials • Working wisdom • Overcoming conventional • Managing labor • Managing job site logistics • Quality assurance PACE S RAWL C RAWL C LOSED C ACE LOSED P MPLEMENTING A Overview if simply having a good It would be wonderful crawl space that design guaranteed a closed But in the controls moisture and saves energy. real world the end result also depends on the materials, process and workmanship that put the good design into practice. There is no trade association or industry- accepted set of standards for implementing closed crawl space systems beyond the requirements of the residential building code. The residential building code specifies minimum requirements for what must be done, not necessarily the process for how it must be done. Therefore, the implementation guidelines Advanced Energy recommends in this section are not legal requirements, but are likely to be critical to the successful implementation of a closed crawl space. Property owners, general contractors, or others can adapt the design and implementation recommendations in this guide to their specific circumstances to create a closed crawl space or they can seek a professional installer to do I C S Section 2 Section MPLEMENTING A I H 20 Closed Crawl Spaces IGH -P ERFORMANCE the house.Arguably, thesemeasuresarenot might requireadditionalefficiency measuresin Codestandard,thesoftware Conservation Model EnergyCodeorInternational If thehomeisrequiredtomeetaparticular savings associatedwithaclosedcrawlspace. analysis maynotaccuratelypredicttheenergy Note thatsoftwareprogramsforenergy and inspection. engineer asanalternatepathforpermitting of approvalfromaregisteredprofessional officials mayrequireoracceptastampedletter end ofconstruction.Insomecases,localcode issuance ofacertificateoccupancyatthe strategies forpreventinganydelayinthe surprises duringconstructionarekey Coming toagreementearlyandavoiding either meetsorexceedsallcoderequirements. closed crawlspacedesignisacceptableand your localcodeofficialstoensurethat Y Officials W use afloor-insulated design. insulation thatitisfinanciallyadvantageousto site mayrequiresuchalargeamountofwall supply airstrategy. Ahomeonasteeplysloped thecrawlspaceinsteadofa dehumidifier todry homeowner withsevereallergiesmaychoosea influence thedesign.Forexample,a occupant requirements,orcostwillalso ou oryourinstallerwillneedtoworkwith orking withCode H OMES materials andprocessesrequired to installa employees aretrainedintheuseof the Y Managing Labor project onschedule. providerto keepthe switch toanotherservice spaces, butinothercasesyoumayneedto acceptability andbenefitsofclosedcrawl resources toconvincetheprofessionalof use theinformationinthisguideorother crawl space.Insomecasesyoumaybeableto or provideawarrantyonhomewithclosed management professionalmayrefusetotreat vented crawlspaces.Forexample,apest do notrecognizethepotentialrisksofwall- spaces needventilationwithoutsideair, orwho professionals whostillbelievethatcrawl conventional wisdomofconstruction installer mayneedtoovercomethe At somepointintheprocess,youoryour Conventional Wisdom Overcoming code officials. how theyensureacceptanceoftheirworkby If youarehiringaninstaller, askcandidates avoid installingtheadditionalefficiencymeasures. andthismayrequirenegotiationto necessary ou oryourinstallerneedtoensure that I PEETN A MPLEMENTING • Foundation or masonry contractor • Foundationormasonry • Sitegradingandpreparationcontractor may needtocoordinatewithincludethe: is turnedovertoacustomer. Contractorsyou system duringconstructionorafterthehouse risk ofdamagetotheclosedcrawlspace ensure properschedulingandtoreducethe coordinating withtheotherbuildingtradesto Y Logistics Managing Job-Site Administration (OSHA)regulations. applicable OccupationalSafetyandHealth respirator fitandlungfunctionaccordingto respirators. Workers mayneedtobetestedfor consider usingfull-facepoweredair-purifying at aminimum.Thosewithbeardsshould Arrestance (HEPA) andactivatedcarbonfilters combined High-EfficiencyParticulate existing crawlspaces.We recommend protectioninbothnewand wear respiratory Advanced Energyrecommendsthatworkers is disturbedinfinishedcrawlspaces, space researchprojectswheneversettleddust of airbornemoldsporesmeasuredinourcrawl during construction,butgiventhehighlevels tested moldlevelsinnewclosedcrawlspaces hazards.AdvancedEnergyhasnot respiratory nature ofthespace.Itmayalsopresent space workisdifficultduetotheconfined closed crawlspacesystem.Naturally, crawl ou oryourinstallerwillneedaprocessfor C LOSED C RAWL S PACE An Introduction for the Southeast 21 ORG . CRAWLSPACES . WWW In some cases, the only feasible strategy for just implementing a closed crawl space may be to build the house with a traditional wall-vented crawl space, and either perform some mold control or cleanup activities during construction, or to wait until the house is complete and then convert the wall-vented crawl space to a closed crawl space, with any desired cleanup. . In these cases, it may be possible to suppress mold growth in the floor structure prior to the crawl space being closed by using pre-treated wood products or applying fungicidal coatings to untreated wood products. If feasible, provide a waterproof covering, secured to resist wind damage, to prevent rain from entering the crawl space when construction will stop for a prolonged period. In such cases, a dehumidifier may also be needed to prevent mold growth. about mold can slow or prevent a home sale. can slow or prevent a about mold a mold may even require Mortgage providers a home purchase. test prior to transport and job-site Often, the processing, and subfloor materials storage of wood framing long periods of time. exposes them to rain for on the job site already The materials may arrive growth or wet enough contaminated with mold the mold spores that to foster germination of exposed to. Using wet they will inevitably be the purpose of any moldy lumber defeats management practices. recommended moisture Building over successfully avoid mold management, ground cover and olunteer-built homes and large homes, olunteer-built Beware of Long Construction Schedules V long particularly large custom homes, often have This construction periods before they are dried in. will makes it even more likely that the crawl space be wet before the house is dried in. long time periods requires a process that includes early rain water dehumidification to contamination. Another strategy could be to build such homes with a temporary and ground vapor retarder to foundation vents and leave the vents open prior dry-in, the at which time you could begin conversion to a closed crawl space. This approach might provide enough drying to avoid potential mold growth during the dryof the year or in times dry construction climates, but likely won’t when occurs primarily in spring or summer. become ideal environments for growing mold environments for growing become ideal Mold the sub-flooring is installed. as soon as space, all surfaces in the crawl can grow on it grows on readily noticed when but it is most excess When the wood framing or subfloor. wood moisture content humidity drives up the are right for to 19% or more, conditions In some cases, surface mold to appear. can grow in as little as dramatic mold blooms mold on the crawl 48 hours. Seeing surface was seldom an issue space wood in the past now public concerns with homebuyers, but PACE S RAWL C LOSED C network wiring contractors • Pest management company • Pest management • Framer • Plumber • Electrician • Insulator • Mechanical contractor • Gutter installation contractor irrigation contractors • Landscaping and/or security system, or computer • Cable TV, you or your installer must In particular, coordinate as soon as possible with the pest management professional to ensure that the closed crawl space system does not interfere if with their treatment or affect their warranty, applicable. For properties under a service the pest management contract or warranty, contractor may be held responsible for any and all damage that occurs to the property after the date of their treatment. This discourages them from contracting on properties with hidden or obstructed areas. In new construction projects, pest management contractors may be reluctant to provide soil pre-treatment, wood pre- treatment, or an alternative pre-construction treatment unless they have sufficient information about the closed crawl space design to believe that they will have adequate access for the pre-treatment or for future inspections or treatments. Managing moisture during the process of construction is critical, because all crawl spaces, including closed crawl spaces, can MPLEMENTING A I H 22 Closed Crawl Spaces IGH -P ERFORMANCE • Apostedsignorsignsidentifyingthe • Awateralarmtoinformthehomeownerofa • Amonitoringsystemtoinformthe of thefollowingqualityassuranceoptions: space systemandwillusuallyofferoneormore long-term performanceoftheirclosedcrawl Quality buildersandinstallerscareaboutthe Assurance Providing Quality construction process. prevent moistureproblemsduringthe in Section3includesstepsdesignedto The sampleimplementationprocesslisted and exteriordoors. by installingtheroof,wallsheathing,windows, untilthehouseisdried-in rain orsnowentry space. Thecrawlspaceisvulnerabletomajor for liquidwaterorvaportoleavethe with sunlight,andthereismuchlesspotential subfloor preventsexcesswaterfromdrying an enclosedspacethatcantrapmoisture.The subfloor isinstalledthecrawlspacebecomes materials,oncethe Even whenyouinstalldry integrity ofthesystem. of theimportancemaintaining informing anyoneenteringthecrawl space different componentsofthesystem and buildup ofliquidwaterinthecrawlspace crawl space homeowner ofrelativehumiditylevelsinthe H OMES • An annual monitoring service toreplace • Anannualmonitoringservice • Arepairkitforfixingsmallareasofdamage air tightness,oradownloadandanalysisof measurements ofwoodmoisturecontentor working order. Thismayinclude that thecrawlspacesystemisingood batteries inmonitoringsystemsandcheck to thelinerafterhouseisoccupied • Inspectthecrawlspaceregularly to: • Ensurethattherearenosolvents,gasoline • Ensurethatdehumidifiersaremaintained • Ensurethatdrainsorsumppumpsare • Ensurethataccessdoorsareclosed, Property ownersshould: contractor todoitforthem. hire aprivatehomeinspectororother basic maintenancechecksthemselvesor owners canperformtheseinspectionsand caught beforetheycausedamage.Property space helpstoensurethatanyproblemsare spaces, butperiodicinspectionofanycrawl Most peopledon’tliketogointocrawl Crawl Spaces Basic Maintenancefor the crawlspace. or otherpotentiallyhazardousmaterials in in properworkingorder per themanufacturer’s instructionsandare functioning properly especially duringwarmweather. I PEETN A MPLEMENTING Photo credit:IndoorEnvironmentalSystems. crawl space… One oftheseitemsdoesn’tbelong ina • Ensurethatanywaterintrusion,especially • Aguaranteeorwarrantythatrelativehumidity ❍ ❍ ❍ out ofthecrawlspace. flooding, isquicklydrainedorpumped intrusion outsidetheinstaller’s control days) withexceptionsforwaterleaksor monitoring pointformorethan7consecutive humidity nottoexceed70%ataspecified target (forexample,aguaranteeforrelative will bemaintainedbelowanagreed-upon data loggingequipment in sensorsoralarms. Check andreplacebatteriesasneeded space. any contractorsworkinthecrawl Ensure thatnodamageoccurswhen by relativehumiditysensors. in acrawlspacemaynotbeindicated problems. Notethatsmallwaterleaks Identify vaporretarderdamageorwater C LOSED C RAWL S PACE An Introduction for the Southeast 23 ORG . CRAWLSPACES . WWW crawl space acceptance of the design air favors venting with outside and safety moisture management and coordination with other trades Summary by a implementation, whether Successful or professional closed builder, property owner, main must address six crawl space installer, topics: of the closed • Defining the design ensure with code officials to • Working wisdom that • Overcoming the conventional including training • Managing labor, • Managing job site logistics, especially • Providing quality assurance if you hire a professional installer, Finally, make sure to establish a well-defined plan and a contract that clearly specifies responsibilities and pricing. Currently in North Carolina, pricing from North Carolina, pricing Currently in space providing closed crawl contractors new general contractors for systems to $3.50 per ranges from $1.00 to construction floor area for a square foot of crawl space Some factors that affect variety of installations. of piers in a crawl pricing are the number below grade, height of space, height above or complexity of the perimeter walls, or the sample installation foundation footprint. These account the cost costs do not take into may realize from not reductions that the builder like insulation or having to install features be included in the drainage, since they may pricing of the closed crawl space system. Initial costs associated with building closed crawl spaces will generally be more than for traditional wall vented construction. As new construction methods are evaluated both by to builders and researchers, it will be important factor in the value of reduced callbacks due to moisture and mold issues, the perception of and potential enhanced value by the consumer, for increased sales price and reduced legal in exposure. Reduced maintenance, a reduction long-term repairs, and significant costly, energy savings enhance the value of closed crawl space construction to the consumer, appraisers and realtors. The future might even include insurance premium reductions for houses built on closed crawl spaces. PACE S RAWL C LOSED C visible mold for a specified period of time, for a specified period visible mold intrusion for water leaks or with exceptions control installer’s outside the by independent third parties sidebar on page 22) crawl space system (see If you choose to hire an installer to implement a closed crawl space, the installer should have a contract or plan that clearly spells out what and what the builder they are responsible for, or other contractors are responsible for. Responsibilities for other contractors might include foundation waterproofing, foundation drains, grading, and/or installation of the drying mechanism if it requires a licensed electrician or mechanical contractor and the crawl space installer is not licensed. Contracts may also specify financial incentives or penalties geared towards ensuring an be efficient installation. For example, there may a trip charge assessed when the builder calls the installer to the site but has not completed the work necessary to proceed, for the installer or a back charge assessed if the builder or to other trades damage the crawl space system the point that it requires repair or replacement of any component. Establishing a Contract Establishing and Pricing • A guarantee or warranty against growth of or warranty against • A guarantee assurance inspections • References for quality maintenance of the • Guidelines for basic MPLEMENTING A I H 24 Closed Crawl Spaces IGH -P ERFORMANCE H OMES An Introduction for the Southeast 25 ORG . CRAWLSPACES . WWW Metal strapping holds this 4 inch (102 mm) diameter supply duct horizontal to ensure proper operation of the butterfly backdraft The balancing damper is visible damper. connection The behind the butterfly damper. to the supply trunk duct is sealed with mastic. backflow damper (for example, a gravity- backflow damper a damper) and either operated butterfly regulator or constant airflow balancing damper foot per airflow of 1 cubic to provide nominal per 30 square feet minute (0.5 liters per second) balancing (4.6 square meters). Traditional over a range of flows. dampers are adjustable provide a calibrated Constant airflow regulators any need for adjustment. amount of flow without be used to achieve Multiple supply vents may desired distribution of the desired airflow and/or adjust the airflow to control If necessary, air. crawl space to the relative humidity in the 70% relative humidity or desired level, typically Flow can be measured with a simple bag- lower. fill method (for an example, see the Resources and References section under Canada Mortgage and Housing Corporation) an anemometer/ a powered flow hood, or a digital air flow meter, passive flow hood. No return air vent is allowed with this method. ROCESS other Advanced Energy research projects and Energy research projects other Advanced of installers in a variety by professional are many North Carolina. There locations in and that can perform acceptably other designs of the North that meet the requirements code. Carolina residential building process presented The sample designs and If you are here are not definitive specifications. or other contractor property owner, a builder, crawl spaces, you will planning to install closed and processes to need to adjust these designs code requirements, your local site conditions, processes and home design, construction occupant needs to ensure success. Recommendation 1 Control humidity in the closed crawl space with dry air from the supply-side ductwork of system. Provide a the house air-conditioning Recommended Humidity Control Methods Some installers and researchers have theorized that the moisture control improvements of closed crawl spaces allow the mechanical contractor to down-size heating and cooling there are few commonly equipment. However, available tools at the time of this writing to calculate the impact of a closed crawl space on the sizing of mechanical equipment for the home, and Advanced Energy research projects have not investigated this aspect of performance. P ONSTRUCTION C ESIGNS AND ONSTRUCTION ROCESS AMPLE Advanced Energy has field tested several closed crawl space designs. This section contains drawings for the designs that proved effective for moisture control and that meet the minimum requirements of the North Carolina residential building code described in Section 4. The numbered callouts refer to notes for each of the specific components in the drawing. This section also includes background information, advantages and disadvantages for the two humidity control strategies used in the sample designs, as well as a sample construction sequence based on processes Advanced Energy uses to have closed crawl spaces built in occupied homes for field research projects. The designs presented here are not the only closed crawl space designs that are acceptable. They are simply examples that performed successfully in the field testing detailed in Section 6. These designs have been utilized in C P Overview S D Section 3 Section ESIGNS AND D AMPLE S H 26 Closed Crawl Spaces IGH -P ERFORMANCE passive, withnoelectroniccontrols. per second).Operationiscompletely delivers 30cubicfeetperminute(15liters duct systempressures.Themodelshown constant rateofairflowoverawiderange modulated, flexiblebladdertodelivera airflow regulator(CAR)usesapressure- This 4inch(102mm)diameterconstant indoor airqualityofthelivingspaceabove. chance thatthecrawlspacewillaffect from thecrawlspacetohousereduces The lackofreturnductorpassivetransfergrill mechanismfortheclosedcrawl space. drying repair it,thusguaranteeingoperationofthe conditioner fails,thehomeownerislikelyto Ifthecentral air exhausts likeclothesdryers. exhaust fansinthehouse,includinglarge unlikely tobeaffectedbytheoperationofother maintenance beyondaperiodicinspection.Itis fully adjustable,andhasnoneedfor This systemisinexpensive,simpletoinstall, Advantages effective inthespringandfallwhen air- Relative humiditycontrolappears to beless Disadvantages H OMES entering thelivingspace.To helpeliminatethe penetrations reducestheriskofcrawl spaceair pressures inthebuilding.Sealing floor leakage, stackpressureorwind-induced effect thatisfarexceededbytheeffectsofduct space airflowcausesanegligiblepressure Advanced Energyfieldtests,thesmallcrawl might thenreturntothelivingspace.In Some oftheairsuppliedtocrawlspace reference tooutsideorthecrawlspace. a smallnegativepressureinthehousewith space withnoreturntothehousecouldcreate operating thesupplyducttoclosedcrawl Theoretically, tightlyair-sealed inavery house, What aboutPressureEffects? Section 4formoredetails. Supplement totheInternationalCodes.See “unvented” crawlspacespecifiedinthe2004 house doesnotmeettherequirementsforan passive transfergrillfromthecrawlspaceto humid weather. Thelackofreturnductor windows anddoorsopentooutsideduring the airhandlerfancontinuously, and/orkeeping choosing nottoruntheairconditioner, running generating excessivehumidityinthehouse, conditioner fromcontrollinghumidityby dehumidify. Occupantscanpreventtheair can reducetheairconditioner’s abilityto has stoppedarebadstrategiesbecausethey fan torunaftertheairconditionercompressor sizing theairconditionerorsettingsystem dehumidification forthecrawlspace.Over- living space,thenitmaynotprovideadequate not providingadequatedehumidificationforthe conditioner useislower. Iftheairconditioneris S AMPLE D Photo credit:IndoorEnvironmentalSystems. foundation ventandhousesawashable filter. unit(CMU)blockor size concretemasonry This outsideairintakereplaces astandard- supply duct. with integratedoutsideairintakeandcrawlspace Schematic representationofcrawlspaceductsystem supply makesuseofsometheexiting through thebuildingenvelope.Thecrawlspace pressurizes thelivingspaceandthenexits such asystem,theventilationairslightly the returnsideofHVAC ductsystem.In intake canbeproperlysizedandinstalledin possibility ofnegativepressure,anoutsideair SGSAND ESIGNS Drawing providedbyIndoorEnvironmentalSystems,©2005. C ONSTRUCTION P ROCESS An Introduction for the Southeast 27 ORG . CRAWLSPACES . WWW sizing guidelines. Dehumidifier capacity sizing guidelines. Dehumidifier ROCESS expensive. Condensate drains require periodic Condensate drains require expensive. liquid if they fail, can allow inspection and, currently no crawl space. There is water in the required for calculating the standard protocol manufacturers provide dehumidifier capacity; general decreases, so decreases as ambient temperature if dehumidification performance must be verified months. is needed in the winter P ONSTRUCTION C Disadvantages Dehumidifiers require periodic maintenance and may not be noticed when they fail. Some units must be re-activated manually after power outages. High-quality models can be Advantages Dehumidifiers are capable of rapidly removing large amounts of water vapor and are independent of the house conditioning system. They can maintain lower relative humidity levels than air conditioning equipment. Low- profile or horizontal-mount units are available to accommodate short crawl spaces. Control water vapor in the crawl space with Control water vapor in installed one or more permanently a minimum 15 pint- dehumidifiers, each with Adjust as needed to control capacity. per-day crawl space to desired relative humidity in the Pipe condensate lower. level, typically 70% or an per local code requirement to outdoors or to interior pump that discharges to outdoors. Provide a dedicated, non-switched, GFCI- protected electrical outlet for the dehumidifier. Recommendation 2 Recommendation ventilation air by using it to dryventilation air the crawl Section 6 it leaves the building. space before on how this system was has details Princeville in Advanced Energy’s implemented research project. ESIGNS AND D AMPLE S H 28 Closed Crawl Spaces IGH -P ERFORMANCE 6. Provide foundationdraintodaylightper toprovideacapillary 5. It isnotnecessary 4. Dampproof orwaterprooftheexteriorwall 3. Slope finishedgradeawayfrombuildingper 2. No openfoundationventsareallowedin 1. Seal exteriorwallpenetrationsandmating Floor Insulation Sample Design:SupplyAirand local residentialcoderequirements. additional moisturecontrol. or interiorcolumns,butthismayprovide between thefootingsandfoundationwalls break (mortaradmixtureorphysicalbarrier) exterior grade. surface whenthecrawlspacefloorisbelow downspouts areonesuchmethod. runoff awayfromthehouse.Guttersand 10 ft.Provideamethodtotransportroof local residentialcodeorfor6in.dropover where required. Install floodventsperlocalresidentialcode access panelorpermanentmaterials. foundations mustbeair-sealed withan exterior walls.Openingstoventilatedporch air-sealed. space accesspanel(s)ordoor(s)mustbe at topandbottomofbandjoist.Crawl surfaces attopandbottomofsillplate H OMES 11. Control moisturevaporinthecrawlspace 10. Airsealallheatingandcoolingductwork 9. Leave aminimum3 8. Insulate floorjoistcavities.Place 7. Seal allplumbing,electrical,duct,cable, return airventisallowedinthecrawl space. airflow and/ordesireddistribution of air. No vents maybeusedtoachievethedesired regulator tocontrolairflow. Multiplesupply balancing damperorconstantairflow Provide abackflowdamperandeither humidity incrawlspacetodesiredlevel. Adjust asneededtocontrolrelative per localresidentialcoderequirement. conditioning system.Setsupplyairvolume with supplyairfromthehouseair- R-value perlocalcoderequirement. ductwork locatedinthecrawlspacewith with aductmasticsystem.Installall R-value requiredbylocalresidentialcode. and ensurethatitissecuredinplace.Use insulation infullcontactwiththesub-floor are notsufficient. Fiberglass orrockwoolinsulationalone floor withfire-stopmaterialsandsealants. and otherpenetrationsthroughthesub- professionals. inspectability bypestcontrol coating overtheinspectiongaptoimprove Optionally, applyalightcoloredpaintor wall withductmasticorequivalentsealant. Seal thetopofvaporretarderto wall. retarder andthetopofmasonry gap betweenthetopofwallvapor ” termite inspection S AMPLE D SGSAND ESIGNS 15. Grade thecrawlspacefloortoone ormore 14. Cover100%ofthecrawlspacefloorwith 13. Anyfuel-firedfurnaces,waterheaters,or 12. Terminate waterheaterdrains, not beconnectedtothecrawlspace drain. foundation drains(interiororexterior) must rodent screening.Gutterdrainsand accessible backflowvalveand1/4-inch drains todaylightandincludean sump pump(s)atlowestpoint(s).Slope low points.Providecrawlspacedrain(s)or ground vaporretarderasnecessary. equivalent. Mechanicallysecurethe fiberglass meshtapeandductmasticor space floor. Sealallseamsandedgeswith columns atleast4inchesabovethecrawl Extend thevaporretarderupinterior inspection gapatthetopofwall. surfaces, leavingtherequiredtermite retarder materialtotheinsidewall Mechanically fastenandsealthevapor a minimum6-milvaporretarder. to outside. gases arepipeddirectlyfromtheappliance appliance andallcombustionexhaust is pipeddirectlyfromoutsidetothe design, meaningthatallairforcombustion should beofa“directvent”or“two-pipe” other applianceinaclosedcrawlspace ventstooutdoors. clothes dryer Te interior pumpthatdischargestooutdoors. condensate drainstooutdoorsoran temperature/pressure reliefpipes,andA/C rminate allkitchen,bathroomand C ONSTRUCTION P ROCESS An Introduction for the Southeast 29 ORG . CRAWLSPACES . WWW 11 7 13 12 15 Supply Trunk Duct Supply Trunk 10 9 8 14 Drawing not to scale ROCESS P 2 ONSTRUCTION C 4 3 1 5 6 Advanced Energy Sample Design: A Closed Crawl Space With Supply Air and Floor Insulation With Supply Air and A Closed Crawl Space Sample Design: Advanced Energy ESIGNS AND D AMPLE S H 30 Closed Crawl Spaces IGH -P ERFORMANCE 7. Seal allplumbing,electrical,duct,cable, andother 6. Provide foundationdraintodaylightper local break toprovideacapillary 5. It isnotnecessary 4. Dampproof orwaterprooftheexteriorwallsurface 3. Slope finishedgradeawayfrombuildingperlocal 2. No openfoundationventsareallowedinexterior 1. Seal exteriorwallpenetrationsandmatingsurfaces Wall Insulation Sample Design:SupplyAirand insulation alonearenotsufficient. materials andsealants.Fiberglassorrockwool penetrations throughthesub-floorwithfire-stop residential coderequirements. but thismayprovideadditionalmoisturecontrol. footings andfoundationwallsorinteriorcolumns, (mortar admixtureorphysicalbarrier)betweenthe when thecrawlspacefloorisbelowexteriorgrade. such method. from thehouse.Guttersanddownspoutsareone Provide amethodtotransportroofrunoffaway residential codeorfor6in.dropover10ft. residential codewhererequired. permanent materials.Installfloodventsperlocal must beair-sealed withanaccesspanelor walls. Openingstoventilatedporchfoundations or door(s)mustbeair-sealed. bottom ofbandjoist.Crawlspaceaccesspanel(s) at topandbottomofsillplate H OMES 11. Controlmoisturevaporinthecrawlspacewith 10. Airsealallheatingandcoolingductworkwitha 8. Insulate thecrawlspacewallovervapor 9. Leave aminimum3 control airflow. Multiplesupplyventsmaybe balancing damperorconstantairflow regulatorto level. Provideabackflowdamper and eithera control relativehumidityincrawlspacetodesired residential coderequirement.Adjustasneededto system. Setsupplyairvolumeperlocal supply airfromthehouseair-conditioning requirement. the crawlspacewithR-valueperlocalcode duct masticsystem.Installallductworklocatedin porous insulationmaterial.Leaveaminimum3 retarder materialwithrigidfoamorothernon- a minimum3 wall.Leave insulation andthetopofmasonry termite inspectiongapbetweenthetopofwall inspectability bypestcontrolprofessionals. coating overtheinspectiongaptoimprove sealant. Optionally, applyalightcoloredpaintor retarder tothewallwithductmasticorequivalent wall.Sealthetopofvapor top ofthemasonry between thetopofwallvaporretarderand comply withlocalfirerequirements. control inspections.Ensurethatbattfacings to facilitateremovalandreinsertionduringpest barrier. Insulatethebandjoistwithbattinsulation installation withoutathermalbarrierorignition local residentialcoderequirementsfor code. Ensurethattheinsulationcomplieswith surface. ObtainR-valuefromlocalresidential of thewallinsulationandcrawlspacefloor ” wicking gapbetweenthebottom ” termite inspectiongap S AMPLE ” 15. Gradethecrawlspacefloortooneormorelow 14. Cover100%ofthecrawlspacefloorwitha 13. Anyfuel-firedfurnaces,waterheaters,orother 12. Terminate waterheaterdrains, D be connectedtothecrawlspacedrain. foundation drains(interiororexterior) mustnot and 1/4-inchrodentscreening.Gutter drainsand daylight andincludeanaccessiblebackflowvalve pump(s) atlowestpoint(s).Slopedrainsto points. Providecrawlspacedrain(s)orsump the groundvaporretarderasnecessary. duct masticorequivalent.Mechanicallysecure seams andedgeswithfiberglassmeshtape 4 inchesabovethecrawlspacefloor. Sealall vapor retarderuptheinteriorcolumnsatleast inspection gapatthetopofwall.Extend inside wallsurfaces,leavingtherequiredtermite fasten andsealthevaporretardermaterialto minimum 6-milvaporretarder. Mechanically appliance tooutside. exhaust gasesarepipeddirectlyfromthe outside totheapplianceandallcombustion all airforcombustionispipeddirectlyfrom “direct vent”or“two-pipe”design,meaningthat appliance inaclosedcrawlspaceshouldbeof outdoors. ventsto kitchen, bathroomandclothesdryer pump thatdischargestooutdoors.Terminate all condensate drainstooutdoors,oraninterior temperature/pressure reliefpipes,andA/C the crawlspace. distribution ofair. Noreturnairventisallowedin used toachievethedesiredairflowand/or SGSAND ESIGNS C ONSTRUCTION P ROCESS An Introduction for the Southeast 31 ORG . CRAWLSPACES . WWW 11 7 13 12 15 Supply Trunk Duct Supply Trunk 10 8 9 8 14 Drawing not to scale ROCESS P 2 ONSTRUCTION C 4 3 1 5 6 Advanced Energy Sample Design: A Closed Crawl Space With Supply Air and Wall Insulation With Supply Air and A Closed Crawl Space Sample Design: Advanced Energy ESIGNS AND D AMPLE S H 32 Closed Crawl Spaces IGH -P ERFORMANCE 7. Seal allplumbing,electrical,duct,cable, 6. Provide foundationdraintodaylightper toprovideacapillary 5. It isnotnecessary 4. Dampproof orwaterprooftheexterior wall 3. Slope finishedgradeawayfrombuildingper 2. No openfoundationventsareallowedin 1. Seal exteriorwallpenetrationsandmating and FloorInsulation Sample Design:Dehumidifier and otherpenetrationsthroughthe sub-floor local residentialcoderequirements. additional moisturecontrol. or interiorcolumns,butthismayprovide between thefootingsandfoundationwalls break (mortaradmixtureorphysicalbarrier) exterior grade. surface whenthecrawlspacefloorisbelow downspouts areonesuchmethod. runoff awayfromthehouse.Guttersand 10 ft.Provideamethodtotransportroof local residentialcodeorfor6in.dropover where required. Install floodventsperlocalresidentialcode access panelorpermanentmaterials. foundations mustbeair-sealed withan exterior walls.Openingstoventilatedporch be air-sealed. space accesspanel(s)ordoor(s)must at topandbottomofbandjoist.Crawl surfaces attopandbottomofsillplate H OMES 12. Terminate waterheaterdrains, 11. Controlhumidityinthecrawlspacewith 10. Airsealallheatingandcoolingductwork 9. Leave aminimum3 8. Insulatefloorjoistcavities.Place temperature/pressure reliefpipes, andA/C for thedehumidifier. switched, GFCI-protectedelectricaloutlet outdoors. Provideadedicated,non- interior pumpthatdischargestoadrainor code requirementtooutdoorsoran to desiredlevel.Pipecondensateperlocal control relativehumidityinthecrawlspace pint-per-day capacity. Adjustasneededto dehumidifiers, eachwithaminimum15 one ormorepermanentlyinstalled R-value perlocalcoderequirement. ductwork locatedinthecrawlspacewith with aductmasticsystem.Installall inspectability bypestcontrolprofessionals. coating overtheinspectiongaptoimprove Optionally, applyalightcoloredpaintor with ductmasticorequivalentsealant. Seal thetopofvaporretardertowall wall. retarder andthetopofmasonry gap betweenthetopofwallvapor are notsufficient. Fiberglass orrockwoolinsulationalone with fire-stopmaterialsandsealants. R-value requiredbylocalresidentialcode. and ensurethatitissecuredinplace.Use insulation infullcontactwiththesub-floor ” termite inspection S AMPLE D SGSAND ESIGNS 15.Grade thecrawlspacefloortooneor more 14. Cover100%ofthecrawlspacefloorwitha 13. Anyfuel-firedfurnaces,waterheaters,or connected tothecrawlspacedrain. drains (interiororexterior)mustnot be screening. Gutterdrainsandfoundation backflow valveand1/4-inchrodent drains todaylightandincludeanaccessible sump pump(s)atlowestpoint(s).Slope low points.Providecrawlspacedrain(s)or vapor retarderasnecessary. equivalent. Mechanicallysecuretheground fiberglass meshtapeandductmasticor space floor. Sealallseamsandedgeswith columns atleast4inchesabovethecrawl Extend thevaporretarderupinterior inspection gapatthetopofwall. surfaces, leavingtherequiredtermite retarder materialtotheinsidewall Mechanically fastenandsealthevapor minimum 6-milvaporretarder. to outside. gases arepipeddirectlyfromtheappliance appliance andallcombustionexhaust is pipeddirectlyfromoutsidetothe design, meaningthatallairforcombustion should beofa“directvent”or“two-pipe” other applianceinaclosedcrawlspace ventstooutdoors. clothes dryer Te interior pumpthatdischargestooutdoors. condensate drainstooutdoorsoran rminate allkitchen,bathroomand C ONSTRUCTION P ROCESS An Introduction for the Southeast 33 ORG . 13 12 11 10 CRAWLSPACES . WWW Dehumidifier 7 15 9 8 14 Drawing not to scale ROCESS P 2 ONSTRUCTION C 4 3 1 5 6 Advanced Energy Sample Design: A Closed Crawl Space With Dehumidifier and Floor Insulation With Dehumidifier A Closed Crawl Space Sample Design: Advanced Energy ESIGNS AND D AMPLE S H 34 Closed Crawl Spaces IGH -P ERFORMANCE 8. Insulate thecrawlspacewallovervapor 7. Seal allplumbing,electrical,duct,cable, and 6. Provide foundationdraintodaylightper local break toprovideacapillary 5. It isnotnecessary 4. 3. Slope finishedgradeawayfrombuildingper 2. No openfoundationventsareallowedinexterior 1. Seal exteriorwallpenetrationsandmating Wall Insulation Sample Design:Dehumidifierand

porous insulationmaterial.Leave aminimum3 retarder materialwithrigidfoamor othernon- rock woolinsulationalonearenotsufficient. fire-stop materialsandsealants.Fiberglassor other penetrationsthroughthesub-floorwith residential coderequirements. moisture control. columns, butthismayprovideadditional the footingsandfoundationwallsorinterior (mortar admixtureorphysicalbarrier)between when thecrawlspacefloorisbelowexteriorgrade. Dampproof orwaterprooftheexteriorwallsurface such method. from thehouse.Guttersanddownspoutsareone Provide amethodtotransportroofrunoffaway local residentialcodeorfor6in.dropover10ft. residential codewhererequired. permanent materials.Installfloodventsperlocal must beair-sealed withanaccesspanelor walls. Openingstoventilatedporchfoundations access panel(s)ordoor(s)mustbeair-sealed. top andbottomofbandjoist.Crawlspace surfaces attopandbottomofsillplate H OMES ” 11. Controlhumidityinthecrawlspacewithoneor 10. Airsealallheatingandcoolingductworkwitha .Leaveaminimum3 9. for thedehumidifier. non-switched, GFCI-protectedelectrical outlet to adrainoroutdoors.Provide dedicated, outdoors ortoaninteriorpumpthat discharges condensate perlocalcoderequirementto the crawlspacetodesiredlevel.Pipe Adjust asneededtocontrolrelativehumidityin with aminimum15pint-per-day capacity. more permanentlyinstalleddehumidifiers,each requirement. in thecrawlspacewithR-valueperlocalcode duct masticsystem.Installallductworklocated professionals. to improveinspectabilitybypestcontrol colored paintorcoatingovertheinspectiongap equivalent sealant.Optionally, applyalight vapor retardertothewallwithductmasticor wall.Sealthetopof the topofmasonry between thetopofwallvaporretarderand with localfirerequirements. inspections. Ensurethatbattfacingscomply and reinsertionduringpestcontrol joist withbattinsulationtofacilitateremoval barrier orignitionbarrier. Insulatetheband requirements forinstallationwithoutathermal insulation complieswithlocalresidentialcode from localresidentialcode.Ensurethatthe the crawlspacefloorsurface.ObtainR-value between thebottomofwallinsulationand wall. Leaveaminimum3 wall insulationandthetopofmasonry termite inspectiongapbetweenthetopof ” termite inspectiongap ” wicking gap S AMPLE 15. Gradethecrawlspacefloortooneormorelow 14. Cover100%ofthecrawlspacefloorwitha 13. Anyfuel-firedfurnaces,waterheaters,orother 12. Terminate waterheaterdrains, D SGSAND ESIGNS space drain. exterior) mustnotbeconnectedtothecrawl drains andfoundation(interioror valve and1/4-inchrodentscreening.Gutter daylight andincludeanaccessiblebackflow pump(s) atlowestpoint(s).Slopedrainsto points. Providecrawlspacedrain(s)orsump vapor retarderasnecessary. equivalent. Mechanicallysecuretheground fiberglass meshtapeandductmasticor space floor. Sealallseamsandedgeswith columns atleast4inchesabovethecrawl Extend thevaporretarderupinterior termite inspectiongapatthetopofwall. the insidewallsurfaces,leavingrequired fasten andsealthevaporretardermaterialto minimum 6-milvaporretarder. Mechanically from theappliancetooutside. combustion exhaustgasesarepipeddirectly from outsidetotheapplianceandall that allairforcombustionispipeddirectly a “directvent”or“two-pipe”design,meaning appliance inaclosedcrawlspaceshouldbeof to outdoors. vents all kitchen,bathroomandclothesdryer pump thatdischargestooutdoors.Terminate condensate drainstooutdoorsoraninterior temperature/pressure reliefpipes,andA/C C ONSTRUCTION P ROCESS An Introduction for the Southeast 35 ORG . CRAWLSPACES . 13 12 11 10 WWW Dehumidifier 7 15 8 9 8 14 Drawing not to scale ROCESS P 2 ONSTRUCTION C 4 3 1 5 6 Advanced Energy Sample Design: A Closed Crawl Space With Dehumidifier and Wall Insulation With Dehumidifier A Closed Crawl Space Sample Design: Advanced Energy ESIGNS AND D AMPLE S H 36 Closed Crawl Spaces IGH -P ERFORMANCE crawl spaceinsuchcases. alternative strategiestoimplementaclosed construction schedulesinSection2for being driedin.Refertothesidebaronlong moisture priortothecrawlspaceandhouse make itmuchmoredifficulttomanage Remember thatlongconstructionschedules high volume. this process,especiallyiftheybuildin will likelyneedtomakesignificantchanges found inmainstreamresidentialconstruction Builders ofthemorecomplexhomestypically homes withsimplefoundationplans. construction ofclosedcrawlspacesinsmall process isgearedtowardslow-volume success. Morespecifically, thissample processes andoccupantneedstoensure code requirements,homedesign,construction and processestoyourlocalsiteconditions, spaces, youwillneedtoadjustthesedesigns contractor planningtoinstallclosedcrawl you areabuilder, propertyowner, orother crawl spacesforseveralresearchprojects.If to haveinstallersconstructeffectiveclosed as wellprocessesusedbyAdvancedEnergy recommendations fromprofessionalinstallers definitive specification;itisbasedon The sampleprocesspresentedhereisnota Sequence Space Construction Sample ClosedCrawl H OMES 6. Whenever possible,maketheinterior walls,eitherfillthe 5. For hollowmasonry 4. Pour footingsandbuildfoundationwall, 3. Locatecrawlspaceaccess(es). 2. Locate crawlspacedrain(s)orsump 1. Locatefootings. Foundation Phase specifications. reinforcement, framinganchors,ormasonry to coverotherrequirementslikefoundation the crawlspaceinstallation.Itdoesnotattempt This processcoversstepsdirectlyrelatedto exterior finishedgrade. finished gradeequaltoorhigherthanthe or usesolidcapblockforthetopcourse. cores ofthetopcourseblockwithmortar through wall. installing crawlspacedrainpipe(s) pump(s). blue waterdrop. construction processareindicatedbythe provide moisturemanagementduringthe Steps thataredesignedspecificallyto S AMPLE D SGSAND ESIGNS 12. Attachandsealwallvaporretardermaterial 11. Airsealallpenetrationsinthefoundation Place backfillagainstthefoundation 10. 9. Ensure thatallpenetrationsinthe 8. Install exteriorfoundationdrainsystem, 7. Grade thecrawlspacegroundtoslope is installed.) the finishedgroundvaporretarder material wall vaporretardercanbeinstalled when horizontally ontotheground.(Alternately, retarder materialapproximately12inches inspection gap.Extendthewallvapor to theperimeterwallwithrequiredtermite perimeter wall. foundation assoonpossible. wall andgradetoslopeawayfromthe exterior offoundationwall,ifapplicable. damp-proofing orwater-proofing on foundation wallarewatertight.Apply Extend foundationdrainpipetodaylight. separate fromcrawlspacedrainsystem. drain(s) orsump(s)location. a. Excavatesumplocationsandprotect b. Extend exteriorportionofcrawlspace a. Installcrawlspacefloordrainand When usingsumppump(s), When usingdrain(s), from collapse. backflow valve. terminate with1/4”rodentscreening. floor drainpipetodaylightand C ONSTRUCTION P ROCESS An Introduction for the Southeast 37 ORG . CRAWLSPACES . WWW rawl Space Work Is C C applicable. duct sealing and crawl space, including air intake, if installation of outside vapor retarder applicable. Ensure that the air handler material is installed under be installed in the unit(s) if the unit is to crawl space. condensate exhaust, bathroom exhaust, drains, and water heater temperature/pressure relief all terminate outside the crawl space. band joist. and all construction debris, wood forms, or organic matter from the crawl space. material, overlapping the horizontal flap of the wall vapor retarder and any other seams by at least 12 inches. 26. Install crawl space supply air duct, if space supply air 26. Install crawl in the other mechanical work 27. Finish all dryer28. Ensure that clothes vent, kitchen 29. Air seal all penetrations in the subfloor and if applicable. 30. Install insulation in subfloor, Complete After ALL 31. Remove temporary retarder ground vapor 32. Install permanent ground vapor retarder 33. Secure the ground vapor retarder as desired. Install and run a temporary dehumidifier to maintain targets of <70% relative humidity or <15% wood moisture content. The dehumidifier condensate must be drained or pumped to outside. Ensure that someone on site is responsible for providing power to the dehumidifier and making sure the dehumidifier is safe from theft. space, including sump pumps and dehumidifier drain, if applicable. space, including at least one permanently wired, non-switched GFCI-protected outlet to accommodate at least one permanent or temporary dehumidifier. access door(s). Spring-loaded hinges access door(s). help to ensure and/or a locked latch can Ensure that that the door stays closed. for keeping someone on site is responsible as possible the door closed as much locking the door at during the day and for the end of every day. the crawl space. If sump pits are drains remain clear. installed, remove water with temporary pumps if needed.

ROCESS 24. Finish all plumbing work in the crawl 25. Finish all electrical work in the crawl Main Construction Phase Main Construction 20. Install and close the crawl space 21. not enter Ensure that roof runoff does 22. are installed, ensure that If drains 23. P ONSTRUCTION C and top of foundation wall. gasket between band joist and sill plate. Apply sealant or gasket between band joist and subfloor. water into the crawl space. mil polyethylene on crawl space ground as soon as possible. Puncture holes in this temporary allow ground vapor retarder to standing water to drain into the ground. Note that it may not be feasible to install the temporary ground cover until after the home is dried-in. around each of the interior piers, extending of the interior piers, around each space inches above the crawl up at least 4 retarder Extend the pier vapor floor. horizontally material at least 12 inches be this could onto the ground. (Alternately, ground vapor done when the finished retarder material is installed.) gap at top and required termite inspection wicking gap at bottom. solid or can be air sealed. Floor Platform Phase 16. Apply gasket or sealant between sill plate 17. Build first floor platform. Apply sealant or 18. that can leak Cover holes in subfloor 19. temporary Install layer of minimum 4- 13. Attach and seal vapor retarder material seal vapor retarder 13. Attach and if applicable, with 14. Install wall insulation, of the foundation wall is 15. Ensure that the top ESIGNS AND D AMPLE S H 38 Closed Crawl Spaces IGH -P ERFORMANCE 42. Remove temporary dehumidifier,42. Removetemporary if 41. ObtainCertificateofOccupancyand 40. Installalaminatedsigninsidethecrawl 39. Confirmthattheaccessdoorisweather- 38. Installpermanentdehumidifier, if 37. If6-milunreinforcedpolyethyleneisused 36. Attachthepermanentgroundvaporretarder 35. Confirmproperinstallationandoperation 34. Sealallseamsinthevaporretarder applicable. permanent powerconnection. need, andaphonenumberforquestions. system, anymaintenancethecomponents components oftheclosedcrawlspace retarder. Thesignshouldalsolistthe and maintaintheintegrityofvapor keep thecrawlspaceaccessdoorclosed space accessdoortoremindpeople stripped, fitswell,andcanbelatched. applicable. that willbeserviced. air handlerunitandanyotherequipment reinforcing materialalongthepathsto for thegroundvaporretarder, provide sump pump(s). material tothecrawlspacedrain(s)or of thecrawlspacedrain. duct mastic. material withfiberglassmeshtapeand H OMES property owner’s monitoring ofthesystem. inspection processes,orasaresponse tothe assurance program,partofabuilder’s warranty occur aspartofacontractinstaller’s quality spring orsummermonths.Theinspectioncould after activationtoverifyperformanceinthehumid inspection) maybescheduledseveralmonths activation. Thisinspection(oranadditional re-inspect thesystemwithinafewweeksof crawl space.Someinstallersmaywantto maintain theintendedrelativehumidityin flow rateordehumidifiersetting,ifnecessary, to system componentsandadjustthesupplyair At alaterdate,verifyproperperformanceofall orinspection. installer orbuilderforservice property ownershouldcontactthecrawlspace space, specifytheconditionsunderwhich monitoring systemisinstalledinthecrawl relative humidityand/orliquidwater sample listofmaintenanceguidelines.Ifa guidelines asdesired.SeeSection2fora and providecrawlspacemaintenance relative humiditycontroltothepropertyowners Provide documentationoftheintendedlevel Post-Occupancy 45. ActivateHVAC system,thensetsupplyair 44. Activatesumppump(s),ifapplicable. 43. Activatepermanentdehumidifier(s),if flow rate,ifapplicable. applicable. S AMPLE D SGSAND ESIGNS C ONSTRUCTION P ROCESS An Introduction for the Southeast 39 ORG . CRAWLSPACES . WWW The 2004 Supplement to the International The 2004 Supplement the problematic insulation Codes retains in the IRC (now section requirement Energy and in the International N1102.2.8) Conservation Code (Section 402.2.8). the Supplement has significantly However, Under Floor Spaces in changed Section R408 noted above in Section the IRC. The exceptions A new section, R408.2 have been deleted. Space, has been R408.3 Unvented Crawl allows construction of added. This new section ventilation openings to a crawl space with no is a sealed ground the outside if (1) there are (2) the perimeter walls vapor retarder, insulated in accordance with Section N1102.2.8, and (3) the crawl space is designed as a plenum or it is designed with either an exhaust ventilation system with an air pathway to the common area or a conditioned air supply with a return air pathway to the common area. There is no apparent compliance pathway for a closed crawl space that is isolated from the living space or that utilizes only floor insulation. The inconsistencies and omissions of the current code demanded a substantial revision in order to create a compliance path that can be consistently followed and enforced for a variety of acceptable closed crawl spaces. A broad group of stakeholders including code Revising the North Carolina Residential Code high in the Southeast to deprive the pest management industry gap of an inspection at the top of the masonry wall foundation and convenient access to the sill plate for inspection or treatment whenever possible. Insulation in ground contact can increase the risk of termite infestation. is extremely impractical in terms of real life construction sequences, access, inspections, and potential pest treatments given currently available insulation materials. The exceptions that allow closed crawl spaces that allow closed crawl The exceptions result are incomplete and as a are vague or to follow or enforce nearly impossible Section R408.2 For example, IRC consistently. crawl space if Exception 5 allows a closed wall perimeter retarder, there is a ground vapor gives no but it air, insulation, and conditioned conditioned air should guidance on how much methods for be supplied or acceptable injecting the air. are problematic for Other sections of the code 5 requires that the technical reasons. Exception be installed in perimeter wall insulation N1102.1.7. Section accordance with Section N1102.1.7 requires the perimeter wall insulation to extend downward from the subfloor to the finished grade level and then vertically and/or horizontally for at least an additional 24 inches (61 cm). This is often referred to as the “L-shaped” method of installing insulation. This method is not viable in the Southeast for two reasons: • First, the risk of insect pest damage is too • Second, the “L-shaped” installation method ODES C UILDING ODES Construction guidelines from agencies like the Construction guidelines (1923) and the National Bureau of Standards (1935) contain Federal Housing Administration that crawl the earliest known recommendations Despite outside air. spaces be ventilated with documented failure in such crawl spaces in the 1930s and a lack of technical justification, the FHA turned these guidelines into requirements in the early 1940s. Since then, building regulations across the United States have required ventilation of crawl spaces with This history is documented by outside air. and Rose, 2002) William Rose (Davis, Warren and shows that there is no scientific basis for current crawl space ventilation requirements. Building research from the 1970s onward has documented that this ventilation may cause or contribute to moisture problems instead of preventing them, and more recent building codes like the 2000 and 2003 versions of the International Residential Code (IRC) have of included language to allow the construction crawl spaces without ventilation openings to these more recent the outside. Unfortunately, codes still require ventilation with outside air as the default, and allow crawl spaces to be approved without any ground vapor retarder. B Historic Origins Section 4 Section C UILDING B H 40 Closed Crawl Spaces IGH -P ERFORMANCE and inspection. alternate pathforpermitting from aregisteredprofessionalengineerasan require oracceptastampedletterofapproval print. Insomecases,localcodeofficialsmay updated NorthCarolinaResidentialCodein enforced in2006withthereleaseof existing printedcode,andthenewcodewillbe December 1,2004asanalternatetothe code wasmadeavailableforreferenceasof approved itinNovemberof2004.Thisnew September 2004andthestateofNorthCarolina adopted thenewcrawlspacecodelanguagein The NorthCarolinaBuildingCodeCouncil showed theydonotperformasintended. unless therewasresearchorfielddatathat and existingrequirementswereleftinplace data indicatedthattheyperformasintended, were addedtothecodewhenresearchorfield closed crawlspaces.Requirementsoroptions a completelynewSection409thatgoverns 408 thatgovernswall-ventedcrawlspaces,and revision. TheendresultwasanupdatedSection over twoyearstocraftthissorely-neededcode North CarolinaDepartmentofInsurancefor Council andthecodeenforcementstaffat worked withtheNorthCarolinaBuildingCode crawl spaces,andproductmanufacturers, builders, buildingscientists,installersofclosed officials, pestmanagementprofessionals, H OMES Residential Code New NorthCarolina Requirements ofthe All CrawlSpaces www.crawlspaces.org Carolina codeinformation,referto takes precedence.ForlinkstoonlineNorth residential buildingcode,thecodelanguage difference betweentheitemslistedhereand residential buildingcode.Wherethereisany here doesnotguaranteecompliancewiththe language, andcompliancewiththeitemslisted section isnotadirectcopyoftheofficialcode wall-vented andclosedcrawlspaces.This requirements ofthenewcodelanguageforboth ofthe This sectionprovidesageneraloverview ✔ ✔ ✔ ✔ basements, porches,andgarages. between thecrawlspaceandadjoining access panelsshallprovide Latched andweather-stripped doorsor penetrations shallbesealed. garages bypermanentwalls.Allutility adjoining basements,porches,and The crawlspaceshallbeseparatedfrom ventsshallterminateoutdoors. Dryer intentionally dischargeinthecrawlspace. drain, ortoaninteriorpumpandshallnot terminate outdoors,toacrawlspacefloor condensate lines,drainpans,etc.)shall W ater drains(e.g.pressurerelief, . ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ space perimeterwallpersectionR327.2.2. provided withfloodopeningsinthe crawl Buildings inflood-proneareasshall be any purpose. before thebuildingisoccupiedorusedfor construction materialsshallberemoved forms forplacingconcreteandother All organicmaterial,vegetation,wood closure systems. approvedduct mastic orotherindustry crawl spaceshallbesealedwithduct All heatingandcoolingductworkinthe insulation isprohibitedasanairsealant. sealants. Theuseofrockwoolorfiberglass sealed withnon-porousmaterials,caulksor All penetrationsthroughthesubfloorshallbe section R401.3. water awayfromthefoundationper The buildingsiteshallbegradedtodrain the finishedgradeaspersectionR406.1. dampproofed fromthetopoffootingto inside grade,theexteriorwallsshallbe Where theoutsidegradeishigherthan perimeter drains. roof gutterdrainsystemsandfoundation Crawl spacedrainsshallbeseparatefrom at eachlowspot. drain todaylightorasumppumpinstalled graded tooneormorelowspots,anda The floorofthecrawlspaceshallbe joints lappedatleast12inches(305mm). exposed earthinthecrawlspace,with retarder orequivalentshallcover100%of A minimum6-milpolyethylenevapor B UILDING C ODES An Introduction for the Southeast 41 ORG . CRAWLSPACES . WWW The crawl space Crawl space air shall be House air shall be blown into House air shall be blown area. No return air duct from the crawl area. No return dwelling air conditioning space to the The crawl space system is allowed. a shall be fitted with supply air duct the entrybackflow damper to prevent of supply duct crawl space air into the fan is not system when the system vent to the operating. An air relief Crawl spaces outdoors may be installed. installed in with moisture vapor control are not to be accordance with this section considered plenums. shall be designed as a heated and/or cooled, conditioned space with insulation on the perimeter wall. Intentionally House air. at the rate of 1 the crawl space with a fan cubic foot per minute (0.5 L/s) per 50 sq. feet (4.6 sq. meters) of crawl space floor area. The fan motor shall be rated for No return air duct from the continuous duty. crawl space back to the dwelling air conditioning system is allowed. An air relief vent to the outdoors may be installed. Crawl spaces with moisture vapor control installed in accordance with this section are not to be considered plenums. Exhaust fan. exhausted to outside with a fan at the rate of 1 cubic foot per minute (0.5 L/s) per 50 square feet (4.6 m2) of crawl space floor area. The fan motor shall be rated for There is no requirement continuous duty. for make-up air. Conditioned space. A permanently installed Supply air from the dwelling Supply air. air conditioning system shall be ducted into the crawl space at the rate of 1 cubic foot per minute (0.5 L/s) per 30 square feet (4.6 sq. meters) of crawl space floor Dehumidifier. dehumidifier shall be provided in the crawl space. The minimum rated capacity per day is 15 pints (7.1 Liters). Condensate discharge shall be drained to daylight or interior condensate pump. Permanently installed dehumidifier shall be provided with an electrical outlet. vapor retarder may optionally be installed vapor retarder edges liner by sealing the as a full interior and beam columns and to the walls such a seams. The top edge of sealing the least 3 inches liner shall terminate at the masonrybelow the top edge of edge of the liner foundation wall. The top interior columns a shall be brought up the the crawl minimum of 4 inches above space floor. may optionally The ground vapor retarder and be protected against ripping a minimum 2 displacement by pouring concrete surface inch thick, unreinforced Floor grading and over the vapor retarder. drain or sump pump requirements still apply. At least one of the following methods of space moisture vapor control shall be provided, and combinations of multiple methods are allowed: ✔ ✔ ent dams, to prevent entry of ground The crawl space perimeter wall shall be air-sealed. Access panels or doors shall be tight- fitting, have a latch mechanism, and be insulated to at least R-2 The minimum 6-mil polyethylene ground surface water, shall be provided whenever surface water, the bottom of the foundation vent opening is less than 4 inches (102 mm) above the finished exterior grade. Insulation must be installed in the floor structure. Minimum net area of ventilation openings Minimum net per foot (0.0929 sq. meter) shall be 1 sq. of crawl 150 sq. feet (13.9 sq. meters) net area may space floor area. Minimum of the crawl space be reduced to 1/1,500 openings are ground area where the cross-ventilation. placed so as to provide 3 feet (914 mm) One vent shall be within When the of each corner of the building. site, the uphill crawl space is on a sloped constructed foundation walls may be without wall vent openings to prevent entry of rainwater. V all-vented Crawl Spaces all-vented ODES ✔ ✔ ✔ ✔ ✔ ✔ ✔ Closed Crawl Spaces W C UILDING B H 42 Closed Crawl Spaces IGH -P ERFORMANCE ✔ ✔ ✔ ✔ require thatthebandjoistareaof the floor space walls.Wall insulationsystems cavities ormaterialsoftheexterior crawl interior surfacesandwithinthestructural on anycombinationoftheexteriorand insulated. Wall insulationcanbelocated space isnotinsulated,thewallsshallbe Where theflooraboveaclosedcrawl conditioned space. to beanintentionallyheatedorcooled, when theclosedcrawlspaceisdesigned that insulationshallbeplacedatthewalls or attheexteriorwalls,withexception space maybelocatedinthefloorsystem The thermalinsulationinaclosedcrawl outdoors aspertheN.C.MechanicalCode. heaters shallobtaincombustionairfrom crawl spacesuchasfurnacesandwater Fuel burningapplianceslocatedinthe by anapprovedthermalbarrier. plenum shallbeprotectedagainstignition plastic insulationlocatedinacrawlspace other prohibitedcomponents.Foam contain plumbingcleanouts,gaslinesor Code. Crawlspaceplenumsshallnot requirements oftheN.C.Mechanical heated orcooledairshallcomplywiththe return airplenumsfordistributionof Closed crawlspacesusedassupplyor ignition byanapprovedthermalbarrier. crawl spaceshallbeprotectedagainst plastic insulationlocatedinaconditioned the dwellingshallbeallowed.Foam space conditioningequipmentthatserves returning airfromthecrawlspaceto H OMES • • Maximumairflowforthesupply • Sumppumpratings • Mechanicalfastenerschedulesforwallvapor • Sizeofcrawlspacedrains • Pitchofgradeforthecrawlspaceground Some examplesare: by thedesigner. element. Suchitemswillneedtobespecified crawlspacedesign requirements forevery The newcodelanguagedoesnotspecify Unregulated Specifications Residential CodeIssues Other NorthCarolina Methods ofsecuringthegroundvaporretarder method drying retarder orwallinsulation height orless. wallsof9inches required onmasonry whichever isless.Noinsulationshallbe below theoutsidefinishedgroundlevel, the interiorgroundsurfaceor24-inches footing orconcretefloor, 3inchesabove down to3inchesabovethetopof foundationwallandshallextend masonry begin 3inchesbelowthetopof frame beinsulated.Wall insulation shall outside airfromflowingintothecrawlspace. incorporate abackdraftdampertoprevent Energy, butifoneisinstalleditshould relief ventisnotrecommendedbyAdvanced moisture controlrequirement.Installingsucha conditioned supplyairisutilizedtomeetthe the outdoorswheneitherhouseairor The codelanguageallowsanairreliefventto Pressure relief related toactualenduseconfigurations. 1040, ASTME152,UL1715,orothertests compliance willstillbeaccepted:FM4880,UL ignition barrier. Thefollowingmethodsof crawl spaceswithoutathermalbarrieror allow installationoffoamplasticinsulationin remove ASTME84asastand-alonetestto Code Councilatthetimeofthiswritingwill Changes awaitingadoptionbytheN.C.Building Plastic Insulation Fire RatingsforFoam B UILDING C ODES An Introduction for the Southeast 43 ORG . CRAWLSPACES . WWW There are several scenarios which may require scenarios which There are several air from the crawl space, you to exhaust example, you existing homes. For especially in harmful soil remove radon or other may need to of crawl space air from gases, ensure isolation are environmental the living space when there present, or hazards like mold or asbestos crawl space odors simply prevent objectionable In these cases, provide from entering the home. air (one example a designed source of makeup that injects house air could be a second fan ensure that the crawl into the crawl space) to create a combustion space exhaust fan won’t hazard or water vapor load. ODES The N.C. residential code allows the use of an The N.C. residential code from the crawl space exhaust fan to take air as an accepted and reject it to the outside required water vapor method for providing the that the makeup control, with the assumption volume of the air comes from the conditioned house above. some risks. First, to This method presents any combustion avoid the risk of backdrafting using exhaust fans appliances, don’t consider in the crawl space unless all combustion appliances in the crawl space are direct vent (“two-pipe”) models, with all combustion air piped directly from outside to the appliance and all combustion gases piped directly from the appliance to outside. Second, there is no guarantee that the make-up air for the fan will come from the house as opposed to outside. The floor air sealing (which the code also requires) reduces the flow of makeup air from the house. House exhaust fans and “stack effect” – the natural action of warm air rising up and out of a home – can reduce air pressure in the house such that air will not flow to the crawl space. When this happens, the air removed from the crawl space by the exhaust fan is more likely be replaced by air from outside – exactly the situation the closed crawl space is designed to avoid. Exhaust Fan Strategies Exhaust Careful Design Require C UILDING B H 44 Closed Crawl Spaces IGH -P ERFORMANCE H OMES An Introduction for the Southeast 45 ORG . CRAWLSPACES . WWW all-vented Crawl Space all-vented rainwater to enter, exterior grade, system, waterproofing, sump pump. At a minimum, wall vented crawl spaces need a At a minimum, wall vented on 100% of the crawl ground vapor retarder steep-sloped earthen space ground, including no plumbing leaks, no walls. There should be of and no intrusion intrusion of ground water, may require: water from outside. This • Adding a system to manage rain water, • fixing leaking irrigation or sprinkler systems, • blocking off low crawl space vents that allow • reducing flooding potential by altering the • sealing off below-grade holes, • adding or repairing a foundation drainage • adding or repairing foundation • fixing plumbing leaks, or • draining standing water, • adding an internal drain system or Steps for Improving a for Improving Steps W crawl space Step 1: Protect the from water sources In existing homes, it can be acceptable to homes, it can be acceptable In existing Besides crawl space in steps. improve the safety, and combustion moisture control with a to proceed carefully another reason cosmetic damage in the conversion is to avoid if the house is dried living area that can occur attention during the too quickly or if lack of drying results in more drying process than is unlikely that wood For example, it is necessary. be dried below 12% framing ever needs to dehumidifiers moisture content, but unattended could dry wood well below this level and the has if the home cause damage. However, for a long time, the experienced wet conditions a materials in the home will have stabilized at high moisture content and some damage may be unavoidable. As the crawl space is dried down to acceptable levels, gaps may open in drywall hardwood floors, wood trim carpentry, surfaces, or cabinetry area. On the in the living other hand, swollen or cupped wooden flooring may flatten out again. Once installed, closed crawl spaces stay drier than wall-vented crawl spaces in the summer and more humid in the winter (see the Research Results for details), which will tend to reduce the range of shrinkage and expansion of those materials over time. ACES P S RAWL ACES C P S VENTED - VENTED - than just closing the vents! ALL RAWL ALL Converting a crawl space is much more MPROVING W Cutting off the flow of outside air into the crawl space is one of the key components of a properly closed crawl space, but all the design elements from Section 1 are needed for success. Simply closing the vents in an existing crawl space will likely cause moisture levels to increase and cause damage, particularly if there is exposed ground without Just closing the vents can be a vapor retarder. downright hazardous if there is combustion equipment located in the crawl space.Does that no middle ground between a wall- mean there’s vented crawl space and a fully closed crawl space with a sealed vapor retarder? No. C Overview crawl space or Improving a wall vented converting it to a closed crawl space can present choices and challenges that are not found in new construction. This section focuses on those challenges and does not repeat the general design information discussed in Section 1. I W Section 5 Section MPROVING I H 46 Closed Crawl Spaces IGH -P ERFORMANCE mold?” inSection7formoredetails. can beeffective.See“ShouldIclean upthe design, thencleanupofsurfacemoldgrowth convert thewall-ventedcrawlspacetoaclosed mold togrow. IfyoucontinuetoStep5and spring andsummerwillmakeitpossiblefor entering throughthecrawlspaceventsin crawl spaceisnotworthwhile,sincetheair At thispoint,cleaningupsurfacemoldinthe caused therotinfirstplace. eliminate allthesourcesofliquidwaterthat either case,Step1mustbecompletedto conjunction withcompletionofStep1.In structurally damagedframingorflooringin is ongoing,youmayneedtoreplaceorrepair in thefuture.Ifrothasoccurredpastor Step 1willhelptopreventrotfromoccurring Eliminating allthesourcesofwaterlistedin damage orrot Step 2:Repairstructural outside thecrawlspace. lines andwaterheaterdrainsmustterminate conditioner ordehumidifiercondensatedrain terminate outsidethecrawlspace.Allair ventsmust bathroom, andclothesdryer future movementordamage.Allkitchen, covers allsoilandissecuredtoprevent vapor retarderswithanewretarderthat Replace damagedordirty, incompleteground H OMES indoor temperatures”meansthermostat surfaces wherecondensationcan occur. “Low in thecrawlspace,bycreatingmore cold this problem,especiallywhenthe ductworkis indoor temperaturesinthesummeraccelerates happens.) Notethatoperatingthehouseatlow explanation ofwhythiscondensation retarder. (RefertotheIntroductionforan pockets orlowareasinthegroundvapor other coolsurfaces,dripdown,andcollectin air willcondenseonductwork,waterpipes,or spring andsummer, andthewatervaporinthat outdoor airtoenterthecrawlspacein foundation ventsthatremainopenwillallow intrusion wasfixed?”Atthispoint,the small puddlescomefromafterallthewater Y the crawlspace. negligible amountofwatervapordiffuseinto hole letsliquidwaterdrainoutbutonlya the soil.Thisisacceptablebecauseasmall punctured toallowsmallpuddlesdraininto present, thegroundvaporretardercanbe vapor retarder. Wheregroundwaterisnot puddles ofliquidwateronthetopnew repaired, youmaystillencountersmall Even ifallthewaterproblemswereproperly have occurred. Step 1andtoensurethatnonewproblems problems weresuccessfullyrepairedin crawl spacetoensurethatallliquidwater Periodically inspecttheimprovedwall-vented intrusion Step 3:Monitorforwater ou mightbewondering,“Wherewouldthese I MPROVING • Cleanoutdebris.Removeanymaterials (e.g. 2, withtheseadditionalsteps: implementation guidelinesfromSections1and space canbeclosedusingthedesignand Once steps1and2areaddressed,thecrawl crawl spacetoacloseddesign Step 5:Convertthewall-vented To from thehouse Step 4:Isolatethecrawlspace appendix onductsealing. condensation. Forreference,seethe surface areathatmayexperience periods, whichreducestheamountofcold into thecrawlspaceduringair-conditioning ductwork alsoreducestheleakageofcoldair building performancecontractor. Sealing combustion safetyinthehomebyaqualified with anoverallassessmentofairleakageand materials andsealductworkinconjunction penetrations inthesubfloorwithfire-blocking will impactthelivingspaceabove,seal those foundincoastalenvironments. settings inextremelyhumidconditionslike North Carolina,butcouldincludewarmer Cincentral F/22° settings oflessthan72°

source formold.Ensurethatyou remove any cardboard, paper, etc.)thatprovideafood reduce thechancethatadampcrawlspace W ALL - VENTED C RAWL S P ACES An Introduction for the Southeast 47 ORG . CRAWLSPACES . WWW develop. Advanced Energy has received five Energy has received develop. Advanced ammonia-like odors reports of strong with the drying-outassociated of existing Carolina, which may crawl spaces in North slowly dying or be caused by the mold persisted for going dormant. The odors dissipating. weeks or months without in conjunction Application of a fungicide levels has been with reducing moisture problem. reported to eliminate this or converted crawl monitor in the repaired space to verify that the improvements are effective or to indicate the need for adjustments to the drying mechanism. Wireless sensors that display the crawl space temperature and relative humidity on a receiving unit inside the house make it very easy for the homeowner or occupant to monitor those conditions. Some of these alarm that sensors include a user-adjustable will indicate when conditions exceed the desired levels. See Section 8 for a manufacturer of such monitors. contamination. Once the crawl space is properly closed, cleaning up surface mold in the crawl space can be effective since the improved crawl space conditions should prevent mold growth from recurring. In general, it is not necessary up to clean mold, but there are a variety of reasons why you may want to do so. See “Should I clean up the mold?” in Section 7 for more details. • Be aware that objectionable odors may that objectionable odors • Be aware and relative humidity • Install a temperature • Decide whether or not to clean mold A crawl space with atmospheric or “natural” draft equipment should not be closed. any fuel-fired furnaces or water Ideally, heaters in a closed crawl space should be of a “direct vent” (often called “two-pipe”) design, meaning that all air for combustion is piped directly from outside into the appliance and all combustion exhaust gases are piped directly from the appliance to outside. Induced-draft combustion systems may be able to operate safely in a closed crawl space with the installation of a combustion air injection system by a The professional mechanical contractor. system must ensure adequate combustion air for the appliance, and installation should include pressure testing to verify proper draft in the combustion vent pipe and proper pressure in the combustion appliance zone with reference to outside. liquid water problems. It may not be feasible problems. It may not liquid water gravity grading or install to correct interior the situations, like when drains in retrofit grade is flat or in a crawl space or exterior sump pumps low spot. In these situations, are or liquid water alarm systems alternatives. heaters or boilers. oil-fired furnaces, water the air, Without sufficient combustion carbon monoxide or appliance can produce back draft. • Provide a mechanism to control or detect mechanism to control • Provide a air for gas- or • Provide adequate combustion ACES P S RAWL C VENTED - ALL existing vapor retarder before new material retarder before new existing vapor and to avoid trapping water is installed or will allow obnoxious molds debris that to Remove rubble to grow. other organisms that is less likely provide a smoother surface retarder material. to damage the new vapor contents (e.g. Ensure that any hazardous chemicals, asbestos, gasoline, household and removed. etc.) are properly handled that will interfere Remove any other objects ground vapor retarder. with installation of the and ductwork Abandoned heating equipment everythingare common finds, but from old broken lawn tires and other trash to toys are found in equipment and children’s crawl spaces. insulation. Porous insulation that has been wetted will likely not recover its rated R- Support value, even after it dries thoroughly. sagging batt insulation in the floor structure with tension wires (sometimes referred to as “tiger teeth”) so that the batts are in continuous contact with the subfloor but is not overly compressed. If there is so much damage that you want to replace all the insulation, use either floor or perimeter wall insulation as desired. If you choose perimeter wall insulation, consult with your pest management contractor to ensure that treatments can continue and that the new insulation will not void your insect pest warranty or bond, if applicable. W • Replace damaged or contaminated MPROVING I H 48 Closed Crawl Spaces IGH -P ERFORMANCE • Ensurethatanywaterintrusion,especially • Inspectthecrawlspaceregularlyto: • Ensurethattherearenosolvents,gasoline • Ensurethataccessdoorsareclosed, Property ownersshould: inspector orothercontractortodoitforthem. checks themselvesorhireaprivatehome perform theseinspectionsandbasicmaintenance before theycausedamage.Pr helps toensurethatanyproblemsarecaught but periodicinspectionofanycrawlspace Most peopledon’tliketogointocrawlspaces, Crawl Spaces Basic Maintenancefor ❍ ❍ ❍ of thecrawlspace. flooding, isquicklydrainedorpumpedout the crawlspace. or otherpotentiallyhazardousmaterialsin especially duringwarmweather. sensors oralarms. Check andreplacebatteriesasneededin contractors workinthecrawlspace. Ensure thatnodamageoccurswhenany humidity sensors. crawl spacemaynotbecaughtbyrelative problems. Notethatsmallwaterleaksina Identify vaporretarderdamageorwater H OMES operty ownerscan I MPROVING W ALL - VENTED C RAWL S P ACES An Introduction for the Southeast 49 ORG . CRAWLSPACES . WWW space and surrounding property, and moisture equipment, insulation quality, problems in the crawl space, and viable spore counts, and leakage through the supply ductwork, return The field study has operated since the summer has operated since The field study findings here we are reporting of 2001, but from the setup used from the experimental of 2004, 2003 through the summer summer of design samples in which is the basis for the technical reports that Section 3. The complete are available are the basis for this section online at www.crawlspaces.org. Quantifying Existing Quantifying Crawl Spaces The characterization study examined ten houses, from 2 to 9 years old, with wall-vented crawl spaces in the Piedmont (central) region of North Carolina. A variety of instrumentation and first hand observation were techniques used to describe the moisture, thermal, and indoor air quality performance of each house. These techniques included: • homeowner interviews, • detailed measurements of the home, crawl • surveys of moisture content, mechanical • bioaerosol sampling and analysis of total • detailed air leakage testing to quantify enWolde, U.S. Forest Products Laboratory;enWolde, The project advisory team includes Dr. Achilles advisoryThe project includes Dr. team Oak Ridge National Laboratory;Karagiozis, John Dr. Duke University; Thomann, Wayne Dr. Canada; of Waterloo, Straube, University of Illinois at Architect Bill Rose, University Joe Lstiburek, Urbana-Champaign; Dr. Physicist Anton Building Science Corp.; T Brennan, Terry and Environmental Scientist Vital support has Camroden Associates. in Solar Center, been provided by the N.C. North Carolina in Raleigh, N.C. and Southface Boone, N.C. Advanced Energy is by no means the first group to investigate the moisture performance of wall vented crawl spaces. Rose (1994) wrote a review of crawl space investigation and Rose and TenWolde regulation through history. (1994) wrote a symposium summary paper to review many of the issues associated with wall vented crawl space construction. The above material, along with that of several others, is included in Recommended Practices for Controlling Moisture in Crawl Spaces, Data Bulletin, volume 10, ASHRAE Technical during the first year of number 3. Additionally, the study Rose contributed an update of the historical review of crawl space regulation as part of a technology assessment report (Davis et al. 2002). These articles reference a wide range of the authors and activities over the years that built the understanding of wall vented crawl space moisture problems and solutions. ESEARCH ESULTS ESULTS Overview over wall-vented By the late 1990s, concern across the crawl space moisture failures among southeast had grown significantly homeowners, builders, and building code officials. The need to quantify existing problems and then compare and document the performance of viable alternatives led Advanced Energy to conduct a study of existing homes and a controlled field study of improved homes. This crawl space project was a multi-year effort to document how various crawl space ventilation and insulation strategies affect moisture levels, energy use, and indoor air quality in real-world, occupied 2002). Another houses (Davis and Warren primary goal of the research was to demonstrate practical, understandable closed crawl space construction techniques that can be transferred to mainstream construction practice. Co-funded by the U.S. Department of Energy the project was directed and Advanced Energy, by Bruce Davis of Advanced Energy and managed by Cyrus Dastur of Advanced Energy Energy Services. of Bill Warren and Bill Warren R R Section 6 Section R ESEARCH R H 50 Closed Crawl Spaces IGH -P ERFORMANCE to affectthelivingspace. contaminants fromthecrawlspacearelikely isolated fromthelivingspaceabove,so showed thatthecrawlspacesarenotwell was leakagethroughtheductsystem.This total leakageofthehouse.Ofthat19%,44% crawl spacerepresentedalmost19%ofthe space airfromthehouseair. Leakagefromthe across thefloorsystemthatseparatescrawl significant airleakagepathwaysmeasured climate. Furthermore,alltenhouseshad moisture acceptablyintheNorthCarolina designed andbuiltarenotsufficienttocontrol vented crawlspacesastheyarecurrently thatwall These findingsconfirmedthetheory vapor retarderatall. the woodframing.Threehomeshadnoground ductwork, withvisiblemoldcoveringmostof rainwater intrusionandcondensationonthe retarder, andthesehomessufferedfrom Only twohouseshadacompletegroundvapor duct leakage. insulation performanceandexcessiveshell compromised thermalperformanceduetopoor levels ofrespirable,viablemoldspores,and multiple moistureproblems,unexpectedlyhigh Findings revealedthatalltencrawlspaceshad system pressureeffects. planes; anddetailedloggingofmechanical ductwork, floorplane,andwall-ceiling H OMES Carolina isroughly0.35CFM50per square T CFM50 persquarefootofenvelope area. the studyhousesvariesfrom0.22 to0.27 be 3%orless.Average envelopeleakagefor upwards of15%.Ideally, ductleakagewould leakage forhomesinNorthCarolinais many differentsizesofhome.Typical duct floor arealetsususeaconsistenttargetacross Dividing theductleakagebyconditioned represents ratesof5%to7%floorarea. from 51to68CFM25forthesegroups,which all thegroups.Average ductleakagevaries and houseleakagetocomparablelevelsacross experimental groups.We reducedductleakage of fourhomeseach:onecontrolgroupandtwo The studyhomesarebrokenintothreegroups provide properdrainage. site soilconditions,andthewasgradedto damage. Thisaddedtotheuniformityof and reducethepotentialforfutureflood several feetofcontrolledfillsoiltoelevateit schedule. Thedevelopmentwasbuilton feet, withthesamefloorplanandwindow street. Allarethesamesizeat1,040square are builtside-by-sideoneachsideofone located inthesamedevelopment.Sixhouses located inPrinceville,NorthCarolina,areall the moistureproblems.These12homes, improved crawlspacestoidentifysolutions study, thisprojectstudied12homeswith In additiontothe10-housecharacterization Experimental Setup Field Study ypical houseleakageforhomesin North (Note thattheNorthCarolinacode inplaceat present, all11foundationventswere retained. of wallventingwhenagroundvapor retarderis building codeallowsareduction in theamount covering 100%ofthesoil.Although to thefoundationwallandintermediatepiers, sealed. Thegroundcoverextendscompletely are lappedapproximatelysixinchesbutnot secured tothesoilwithturfstaples.Theseams polyethylene groundcoverthatismechanically foundation vents.Eachhousehasasix-mil vented crawlspaces,witheleven8”x16” The fourcontrolhouseshaveconventionally mechanical system. timing orfan-cyclingcontrolsareusedinthe and thendistributedtothehouse.Nofan- mixed intothereturnairstream,conditioned, operating, 40cfmoffilteredoutsideairis return plenum.WhenevertheHVAC systemis media filterandthenconnectsdirectlytothe outside routsairthroughaone-inchpleated ductwork. Asix-inchinsulatedflexductfrom ventilation intakeintegratedwiththeHVAC houses. Allthehouseshaveanoutsideair measured andcorrectedasneededinall refrigerant chargeandsystemairflowwere 10.0 SEERand6.8HSPF. Heatpump pump is22,000BTU/hr. withefficienciesof heat pump.TheARIratedcapacityofthe the samemakeandmodelofpackaged-unit corrected inallhouses,and12homeshave Floor andceilinginsulationdeficiencieswere leakage target. Advanced Energy’s standardhouse foot envelopearea,whichisthesameas R ESEARCH R ESULTS An Introduction for the Southeast 51 ORG . CRAWLSPACES . WWW recorded outside air temperature and recorded outside air temperature measured wood moisture content on a

Instrumentation and Instrumentation Data Collection We three battery-operatedmoisture content using across the data loggers distributed shielded from rain development in locations type of used the same and direct sun. We inside each house logger to record conditions space. Measurements and inside each crawl intervals.were recorded at 15-minute The placed at the center of house data logger was closet and two return the house in the HVAC loggers (one extra for redundancy) were located together in the center of the crawl space on the support beam for the floor joists. We 60-day intervaleach crawl at ten locations in space, including sill plate, band joist, floor joist, center beam, and subfloor readings. After seeing the potential for energy savings during a billing analysis in early 2003, we outfitted all 12 houses with electricity sub- meters to record exact energy consumption by package-unit heat pump system. each home’s The whole-house meter and sub-meters are read monthly. The crawl space experiment has been monitored for more than three years at the time of this writing. Ongoing measurements clearly indicate that the closed crawl spaces consistently outperform the wall-vented crawl spaces in terms of both moisture control and hinge prevents movement of air from the crawl movement of air from hinge prevents the supply plenum when space into the system is off. spaces are insulated Four of the closed crawl batts in the with R-19 Kraft-faced fiberglass with the with the Kraft facing in contact floor, with and the other four are insulated subfloor, polyisocyanurate 2 inches of R-13 foil-faced wall and on the band foam on the perimeter foam was installed with joist. This closed-cell the top of the foam a three-inch gap between plate to allow for and the bottom of the sill is a and there monitoring of termite activity, second gap at the bottom of the foam insulation to prevent ground contact and wicking of moisture into the foam insulation. This foam meets the ASTM E84 and Factory Mutual FM 4880 requirements of the 2000 International Residential Code for installation without a thermal barrier. The ground vapor retarder is attached to the inside surface of the foam insulation with tape or fiberglass mesh tape and duct mastic. We in specifically did not install the wall insulation the IECC-required form, which specifies wall insulation down to 24 inches below outside grade or horizontally on top of the soil in from the foundation wall for 24 inches. Instead, the bottom edge of the crawl space wall insulation was only 3 to 6 inches below outside soil grade level. ESULTS the time of construction (the 2000 International construction (the 2000 the time of the ground Code) does not require Residential the net since these vents provide vapor retarder to meet the 1:150 ventilation-area free area to The floors of crawl-space-area requirement). insulated with well- the control houses are fiberglass batts. installed R-19 Kraft-faced of the experiment homes The crawl space vents polystyrene foam and were sealed with rigid Each of these duct mastic or spray foam. a sealed, six-mil closed crawl spaces has the floor and polyethylene liner covering wall, stopping extending up the foundation three inches from the top of the masonry to of provide a termite inspection gap. The seams the liner are sealed with fiberglass mesh tape and duct mastic, and the edges are sealed with duct mastic and mesh tape to the foundation wall or intermediate piers. The liner is mechanically secured to the soil with turf staples and to the foundation wall with a furring strip. Mechanical drying spaces in the closed crawl is provided by a 4-inch duct that provides 35 cfm of conditioned air to the crawl space from is the supply plenum whenever the air handler running. As designed, the extra air simply exfiltrates through the crawl space perimeter wall. No fan-timing or fan-cycling controls are used in the mechanical system, and no stand- alone dehumidifiers are used for moisture control. A balancing damper permits and a back-flow adjustment of the flow, butterfly gravity damper with a non-metallic R ESEARCH R H 52 Closed Crawl Spaces IGH -P ERFORMANCE 100% ofthesoilisnotsufficientto control maintained groundvaporretarder covering fact thatevenacarefullyinstalled and mildest conditions. the ventedcrawlspacesdidundereven performance undertheharshestconditionsthan The closedcrawlspacesprovidedfarbetter relative humidityabovethegiventhresholds: different crawlspaceshadadailyaverage percent oftimeineachsummerthatthe drought year. Thetablebelowcomparesthe Carolina, while2002wasarecord-setting inthispartofNorth in recordedhistory As fatewouldhaveit,2003wasthewettestyear access doorclosed. crawl spacesupplyductwasopenedandthe the humid2003summerseasonassoon crawl spacesbeganasteadydeclinethrough Daily averagerelativehumidityintheclosed which aresummarizedinthefiguresbelow. temperature), andwoodmoisturecontent, (presented forconvenienceasdewpoint regard torelativehumidity, absolutemoisture notably betterthantheventedcrawlspaceswith The closedcrawlspacesinthisprojectperform Moisture Performance summer of2004. ranging fromthesummerof2003through section offindingsfromaone-yearperiod energy use,andherewe’llpresentacross- H OMES These resultshighlightthe ground vaporretardermayprevent woodrotin spaces withoutwaterintrusionand witha100% W space, evenwithexcellentexterior drainage. relative humiditylevelsinawall-ventedcrawl ell-constructed, extensivelywall-vented crawl

Relative Humidity (%) 100 RH Threshold u-3Jl0 u-3Ag0 e-3Ot0 o-3Dc0 a-4Fb0 a-4Ar0 a-4Jun-04 May-04 Apr-04 Mar-04 Feb-04 Jan-04 Dec-03 Nov-03 Oct-03 Sep-03 Aug-03 Aug-03 Jul-03 Jun-03 bv 0%7%0 8 %9%0% 13% 100% 0% 0% 100% 92% 100% 70% 64% 100% 7% 5% 100% 100% 0% 0% 98% 100% 0% 86% 100% 23% 0% 94% 0% Above 50% 0% 79% Above 60% 39% 0% Above 70% Above 80% Above 90% 40 50 90 30 60 70 80 20 Summer (June-August)RelativeHumiditySummary Crawl SpaceandOutdoorRelativeHumidity etdCoe etdCoe etdClosed Vented Closed Vented Closed Vented W all Vented 0220 2004 2003 2002 Closed construction. installation andm the usualpoorqualityofgroundvapor retarder even worseintypicalventedcrawl spacesgiven crawl spaces,butwatervaporcontrolwouldbe Outside aintenance in Jul-04 general Aug-04 R ESEARCH R ESULTS An Introduction for the Southeast 53 ORG . CRAWLSPACES . WWW May-04 Jun-04 Jul-04 Aug-04 Closed + 2'' Foam on Wall Outside Feb-04 Mar-04 Apr-04 Closed Closed + R-19 Floor verage Wood Moisture Content verage Wood A all Vented W Sep-03 Oct-03 Nov-03 Dec-03 Jan-04 Crawl Space and Outdoor Dew Point Temperature and Outdoor Dew Crawl Space 03 Aug-03 ented + R-19 Floor V Aug 2003 Oct 2003 Dec 2003 Feb 2004 Apr 2004 Jun 2004 Jun-03 Jul-03 Aug-

35 15 25 65 75 55 45

Dew Point (F) Point Dew 8.0 6.0

16.0 14.0 12.0 10.0 18.0 ood MC (%) MC ood W ESULTS The dew point temperature graph shows that temperature graph The dew point vapor than air contains more water the outside during wall-vented crawl spaces the air in the water vapor actually adding the warm season, instead of providing drying potential. Consider of the outside air at this: the average dew point of 2003 was Princeville during the summer 73° F (23° to conditions C). This corresponds of 88° F (31° humidity. C) and 60% relative the crawl space and When that air goes into than 73°encounters anything cooler the F, at 100% and the water relative humidity peaks on that object. vapor in the air can condense Supply ducts (55-65° 13-18° F, C), water pipes and tanks (55-65° F), and even the floor of the crawl space (65-70° 18-21° F, C) and the wood framing above (70-78° 21-26° F, C) if can experience this condensation, especially the homeowners condition their house to temperatures below 72° F (22° C). Even if conditions aren’t bad enough for condensation, the relative humidity of the air entering the crawl space will still easily reach levels of 90% or higher for prolonged periods of time. the The dew point measurements also highlight fact that the closed crawl spaces stay more humid than the wall-vented crawl spaces in further reducing the moisture swing winter, seen by the house over the course of the year. This can in turn reduce the likelihood of common cosmetic problems like shrinking and or swelling of hardwood floors and wood trim, cracking and “nail pops” in drywall. R ESEARCH R H 54 Closed Crawl Spaces IGH -P ERFORMANCE proper sitewatermanagement. impact ofthe100%groundvaporretarderand existing crawlspaces,showingthebeneficial spaces ismuchlowerthanfoundintypical moisture contentinthewallventedcrawl species ofwood-boringbeetlepests.Wood inhospitabletoSoutheastern termites andvery islessattractiveto because woodthisdry likelihood ofsurfacemoldgrowthbutalso notable, notonlybecauseitreducesthe closed crawlspacesstaysbelow12%is moisture contentintheframinglumber spaces. Thefactthattheaveragewood shows readingsforthethreetypesofcrawl The averagewoodmoisturecontentgraph

Temperature (F) 20.0 30.0 40.0 50.0 60.0 70.0 80.0 u-3Jl0 u-3Sp0 c-3Nv0 e-3Jn0 e-4Mr0 p-4May-04 Apr-04 Mar-04 Feb-04 Jan-04 Dec-03 Nov-03 Oct-03 Sep-03 Aug-03 Jul-03 Jun-03 V ented +R-19Floor H OMES A verage DailyCrawlSpaceandOutsideTemperatures Closed +R-19Floor Date weather, especiallyinwindyconditions. closed crawlspaceduringsub-freezing freeze damagetopipesorappliancesinthe open ventsreducetheriskofintermittent during thewintermonthsandabsenceof Wa T houses. Thisistrueevenforthefourclosed significant energysavingsoverthecontrol crawl spacehomesexhibitedclearand Going beyondinitialexpectations,theclosed Energy Performance emperature Conditions rmer temperaturesinclosedcrawlspaces Closed +2''FoamonWalls Outside small samplesize. groups thatmaybesignificantdue tothe occupant thermostatsettingsamong the variations inbaseloadconsumption and equipment performance,thereremain leakage, ductandmechanical site drainage,architecture,insulation,shell While wecontrolledthevariablesofclimate, Factors AffectingEnergyUse per yearforeachhousehold. approximately 1025kWh(orroughly$103) period, whichrepresentsasavingsof control housesoverthesame12-month used onaverage18%lessenergythanthe The wall-insulatedclosedcrawlspacehouses year foreachhousehold. of approximately870kWh(orroughly$87)per the controlhouses,whichrepresentsasavings 15% lessenergyforspaceconditioningthan closed crawlspacehousesusedanaverageof For the12monthsanalyzed,floor-insulated control housesisreportedintheinsettable. The percentageofsavingsascomparedtothe “Average SeasonalHVAC UseperHouse”chart. average houseineachgroupisshownthe Energy usedforheatingand/orcoolingthe as isrequiredbyenergycodes. or 24”horizontallyontothecrawlspacefloor, have insulationinstalleddown24”belowgrade included atermiteinspectiongapanddidnot crawl spacehouseswithwallinsulationthat R ESEARCH R ESULTS An Introduction for the Southeast 55 ORG . CRAWLSPACES . WWW have not administered a formal survey of

Impact of Moisture Load on Moisture Load Impact of and Energy Use Comfort house data indicated A review of the interior were operated 1°that the control houses to 2° houses in the F cooler than the experiment summer of 2003 and 1°2° to warmer than F in the winter of 2003- the experiment houses account for a portion 04. This behavior could recorded, or it could of the energy savings we the moisture benefits of be another indicator of since humidity levels the closed crawl spaces, comfort and the play a large role in occupant point temperatures in data shows that the dew all the homes were very consistent. We occupant comfort, but had an experience that indicated the impact of crawl space performance on occupant thermostat settings: in June of 2004 we upgraded three of the four wall-vented control crawl spaces to test a new installed a version of closed crawl space. We crawl space supply duct to provide supplemental drying, in the other as was done closed crawl spaces. When we returned to the one resident (who rarely site four days later, adjusts her thermostat) excitedly let us know that the night after we closed her crawl space, she turned up her thermostat because she felt too cold in the house. This anecdotal evidence suggested that the difference in indoor set point temperatures may not be a simple matter of homeowner preference that reduces the measured energy savings, but instead be a result of the improved performance of the closed crawl spaces which deserves more Annual Closed + R-13 Wall Spring (Mar-May '04) (Mar-May ed with 36 % 10 % 28 % 18 % +4 % 13 Wall - - - - R- Clos experiment houses is about the same in both which suggests that the summer and winter, surpluses offset each other in terms of heat pump energy used/saved in the control houses to compensate for the difference. However, there is a greater difference in base load consumption between the control houses and the wall-insulated experiment houses in the which summer than there is in the winter, makes the summertime wall-insulated house performance look better. Winter ed with 22 % 10 % 19 % 15 % -5 % -5 - - - - (Dec '03-Feb '04) 19 Floor R- Clos Closed + R-19 Floor pring Fall Fall avings S Winter Annual Summer S (Sep-Nov '03) verage Seasonal and Annual HVAC Use per House and Annual HVAC verage Seasonal A all-Vented W Summer (Jun-Aug '03) 7 6 5 4 3 2 1 0

did not sub-meter the appliance, lighting,

Thousands kWh ESULTS We water heating or exhaust fan loads, but noted that the total base load use in the control homes was significantly higher (10-20% in any given month) than that of the experiment By luck of the draw, homes over the entire year. the control homes had higher occupancy numbers and greater numbers of children relative to the experiment houses. The extra occupant and base load in the controls would theoretically increase the need for cooling in the summer and decrease the need for heating The difference in base load usage in the winter. between the controls and the floor-insulated R ESEARCH R H 56 Closed Crawl Spaces IGH -P ERFORMANCE summer of2003tothe2004. the crawlspacesandlivingareasfrom exposure, weconductedradonmonitoringin health ofthehomeownerswithregardtoradon designs werenotnegativelyimpactingthe To Radon Measurements closed crawlspacehomes. 2 degreescoolerthantheoccupantsin continued tooperatetheirhouseanaverageof remaining wall-ventedcrawlspacehome homes, whiletheoccupantsoflast temperatures intheotherclosedcrawlspace homes withinanaverageof0.5degreesthe upgraded crawlspacehomesoperatedtheir and Augustof2004,theoccupantsthree detailed investigation.Subsequently, inJuly

ensure thattheseclosedcrawlspace H OMES Radon (pCi/L) 0.5 1.5 2.5 3.5 0 1 2 3 4 Princeville 2003-04RadonLevels os Crawl House V ented Closed All othermeasurementswerebelow1.0pCi/L. spaces, withvaluesof2.0,1.5and1.4pCi/L. measurements alloccurredinclosedcrawl in anyhouse.Thethreehighestcrawlspace 0.5 pCi/lwithamaximumreadingof0.7 type; allhousesaverageapproximately show adifferencecorrelatedwithfoundation radon measurementsinthelivingspacedonot and 1.1pCi/lintheclosedcrawlspaces.The averaging 0.5pCi/lintheventedcrawlspaces in theclosedcrawlspaces,withmeasurements indicate slightlyhigheraverageconcentrations The measured2003-04long-termresults below 2pCi/Lisdifficult. between 2and4pCi/L.Reducingradonlevels consider fixingthehomewhenlevelsare radon levelsareabove4pCi/L.Oneshould Radon” homesshouldberemediatedwhen According totheEPA’s “ACitizen’s Guideto composting facilities. fields,contaminatedrooms,or harvesting largesources–e.g. presence ofvery measured inthisprojectarefound onlyinthe viable andtotalsporecountsashighwere the firstroundofsamplingin2001.Generally, were measuredinallthecrawlspacesduring spaces, butlargenumbersofmoldspores vented crawlspacesthanintheclosed samplers, weresignificantlyhigherinthewall- T spaces werethehighestofgroup. space abovetwoofthewall-ventedcrawl measurements, butmeasurementsintheliving significantly lowerthantheoutside Measurements inthelivingspaceswere in thelivingspaces2001and2002. viable sporesinthecrawlspaces,outside,and Anderson samplerswereusedtomeasure Mold SamplingResults control withabasementorslabfoundation measures usedforradonassessmentand being builtinaradonriskarea,thesame and mitigation.Iftheclosedcrawlspaceis a shortbasementwithregardtoradontesting recommends treatingclosedcrawlspaceslike closed crawlspaces.AdvancedEnergy radon levelsdoappeartocorrelatethe EPA actionthreshold,thehighermeasured While thecrawlspacelevelswereallbelow are applicable. otal sporecounts,measuredwithBurkard R ESEARCH R ESULTS An Introduction for the Southeast 57 ORG . CRAWLSPACES . WWW won’t know with any certainty how well the with any certainty how won’t know

wo of the field study homes were highly We improvements in moisture and energy improvements in other will transfer to houses performance constructed a number are actually climates until Energy has begun a and monitored. Advanced data in multiple new project to gather that the ability of climate zones while demonstrating market to incorporate the production housing into its closed crawl space technology construction processes. energy benefits of Currently we find that the not accurately predicted closed crawl spaces are software, so it may by popular energy analysis be some time before closed crawl spaces get their due respect when builders are choosing house specifications aimed at achieving a certified minimum energy rating. Future research will include a detailed analysis of a variety of software tools, with the goal of identifying improvements needed in the tools and to reinforce the finding that consumers can improve the efficiency of their homes by building or retrofitting a properly closed crawl space. T instrumented and monitored by Oak Ridge National Laboratory the (ORNL) throughout The data collected duration of the field study. from these houses has been used to calibrate hygrothermal and validate a computer-based modeling software tool. This software tool can now predict the hygrothermal performance of different crawl space designs when given basic thermal and moisture characteristics of the materials to be used in the design, along with environmental conditions. . believe the findings of this study will

www.crawlspaces.org shown by the The performance improvement closed crawl spaces is impressive, especially considering that the control houses likely represent the best possible performance of wall-vented crawl spaces. The vast majority of newly built wall-vented crawl spaces are not installed or maintained to the standards used for this project. We Research Implications Research project is field demonstration The Princeville in April of 2005. During scheduled to conclude Advanced Energy will the winter of 2004-05 configuration to assess test a new crawl space 24-inch wide strip of the energy impact of a horizontally on R-10 foam insulation installed closed crawl the ground of the wall-insulated, and additional space houses. Final results on the project website, analysis will be posted transfer well to houses of similar geometry and geography to the study homes. However, additional consideration and study are required for houses in other locations and with different The energy results seem to indicate geometry. that wall-insulated closed crawl spaces will perform best in cooling-biased climates while closed crawl spaces will perform floor-insulated best in heating-biased climates. Of course, these homes have shallow foundations, and we have not tested crawl space foundations with deeper footing depths such as may be found farther north. A wall insulation strategy may also prove to perform best in such houses. ESULTS In the case of these crawl spaces, there were of these crawl spaces, In the case surrounding factors. First, the two contributing before by heavy rains shortly area was deluged in were made. This is reflected the samples outdoor air data. both the crawl space and procedure required the Second, the sampling crawl space, stirring up technician to enter the contributed to the settled dust, and this likely strikingly high as sampled levels being as they were. we inserted the sampler In subsequent testing, a long cantilever so into the crawl spaces on not have to enter and that the technician would stir up settled dust. These readings were in fact much lower than the initial samples. After the the cantilever sample was complete, we verified a impact of entering the crawl space by having technician crawl inside the crawl space and take a followup sample. These followup samples, whether in the closed or wall-vented crawl spaces, showed a large increase in these airborne spores. Most importantly, findings point to the need to wear respiratory protection in all crawl spaces, even if there is no visible mold. See Section 7 for background information on molds and health impacts of mold exposure. R ESEARCH R H 58 Closed Crawl Spaces IGH -P ERFORMANCE H OMES An Introduction for the Southeast 59 ORG . CRAWLSPACES . WWW humidity levels below the 70% threshold humidity levels most molds. required by decompose enzymes that may Hyphae exude nutrient can be organic materials so the mat. That, in fact, is absorbed into the hyphal decompose dead their ecological job – to are essential to the plants and animals. Molds natural world. proper workings of the at digesting Most molds are not good rot, decaying fungi (soft cellulose. Wood are the organisms that white rot, or brown rot) wood, and they actually decompose solid generally require very wet wood with a moisture content of 30% or more. Soft rot requires the continual presence of liquid water. Brown rot usually occurs on wood in contact with damp soil or a continuous water source, but can also be caused by molds that transport moisture from some other location (this latter type is typically referred to as “dry rot”). Crawl spaces with long-term condensation, or exposed soil are vulnerable standing water, to any of these molds, especially at low temperatures caused by air conditioning below 72° F (23° C) or in colder climates with low soil temperatures. Sap stain or blue stain fungi may cause discoloration of cut lumber but are not reported to lead to rot or structural damage and probably do not present an air quality concern. Sap stain fungi can be mistaken for Stachybotrysdark species due to their coloration, but scientists note that the growth of Stachybotrys species on wood is extremely Mold reproduces by sending microscopic Mold reproduces on water. on the air or floating spores sailing of 3 to 40 are typically in the range Mold spores hair is size; for reference, a human microns in A in diameter. typically 100 to 150 microns millions of spores. small colony may release a sample of outdoor When it is above freezing, the United States is likely air almost anywhere in thousands of mold to contain hundreds or almost Consequently, spores per cubic meter. have spores attached all environmental surfaces to avoid them. – it is virtually impossible most grow into a colony, In order to sprout and spores need to be in a location that provides oxygen, liquid water and/or relative humidity greater than 70%, a source of carbon, and temperatures between 45° F (7.2° C) and 100° F (37.8° C). Once most molds have germinated, they do not need liquid water to these continue growing. Unfortunately, conditions are found in nearly every wall- vented crawl space in the southeast for much Because crawl spaces have of the year. numerous air path connections to the house via plumbing penetrations, electrical penetrations, leaky ductwork, and more, we a could say that the crawl space is “MADD” – Mold Amplification and Delivery Device. Because spores, carbon sources, warmth, and dark spaces are found in all houses, the only is realistic strategy for controlling mold growth to control moisture levels. Eliminating liquid water is the first step. Controlling relative humidity is the second step and fortunately, most people are more comfortable at relative OLD M OLD BOUT M A UESTIONS OMMON BOUT Mold, together with mushrooms, bracket fungi, and puffballs are classified as fungi. These strands organisms consist of a mat of hair-like called hyphae that form both the main body and fruiting bodies that make spores. Spores are essentially baby fungi with a lunch box. Mushrooms, puffballs, and bracket fungi have large, easily seen fruiting bodies, while molds have tiny fruiting bodies that are visible as a surface discoloration only when there are many of them. Mold coverage ranges from light spotting to thick blooms that cover large areas. to They can range in color from black to green white, yellow and red and be present as discrete speckles or large fuzzy masses. What is Mold? This section summarizes detailed mold This section summarizes in several of the information that is presented ACGIH, 1999; technical references, specifically Fallah, 2004 and Davis, 2002; Burge, 2004; we offer Brennan, 2005. In addition, recommendations based on Advanced Energy research findings and building investigations. C Q A Section 7 Section UESTIONS Q OMMON C H 60 Closed Crawl Spaces IGH -P ERFORMANCE moisture source. mold growthistoremovethemold’s Whether visibleornot,thekeyto suppressing or aresimplynotvisibletothenaked eye. some cases,moldsarelocatedinhiddenareas moisture problemthatrequiresattention.In Visible mold,regardlessofspecies,indicatesa to getreliablemoldsamplingandanalysis. it isgenerallyexpensiveandtime-consuming identify samplesbyspecies.Asdetailedbelow, testing unlessthereisaspecificneedto Advanced Energydoesnotrecommendmold Should ITestforMold? prevent damage. quicklyto must bedriedandcleanedvery digest theadhesives.Compositematerials degraded bymoldsbecausethemoldcanoften bits ofwoodandadhesivescanbestructurally like engineeredwoodproductsconsistingof cause structuraldamage.Compositematerials generally limitedtothesurfaceanddoesnot ambient relativehumidityabove70%)is conditions (19-30%woodmoisturecontentor Growth ofotherfungionsolidwoodindrier They arenotoftenfoundincrawlspaces. repaired plumbingleaksorstandingwater. levels ofmoistureresultingfromflooding,un- These moldsareassociatedwithconstanthigh fiberboard, gypsumboard,paper, dustorlint. (e.g. S.atraorchartarum)typicallyoccuron species poor andrarelyoccurs.Stachybotrys H OMES mold growthinabuilding(orpart ofthe distinguishing whetherthereisindependent Speciation providesbetterevidence for species ofmoldpresentinthesample. or countedandcategorizedbyindividual Ideally, moldsamplesshouldbe“speciated,” • Bioaerosolsamplingrequirestrained • Insamplesetstakenatafewlocationsover uncertainty: bioaerosol samplingisfraughtwithsourcesof Unfortunately, interpretingtheresultsof is growinginsidethebuilding. indoors thanoutdoors,itisevidencethatmold the speciesmixissignificantlydifferent significantly higherindoorsthanoutdoorsor same time.Ifthesporeconcentrationsare samples withoutdoortakenatthe Hygienists (ACGIH),istocompareindoor Conference ofGovernmentalIndustrial sampling, aslaidoutbytheAmerican The generallyacceptedpracticeforbioaerosol varied byafactoroffive. samples takenwithinhoursofeachother in Section6,outdoorviablesporecount sampling duringthefieldresearchdescribed over shorttimeframes.Incontrolledair significantly even then,measurementsvary technicians withspecializedequipment,and made overextendedtimeperiods. been missed,numeroussamplesmustbe the chancesthatsomethingimportanthas and falsenegativesarecommon.To reduce ofhoursordays,falsepositives an interval health impactsandthereportingof moldby symptoms insusceptibleindividuals. Potential trigger allergies,asthmaevents,or other dries out.However, dormantmoldcanstill space. Moldsgodormantastheirenvironment up aspartofastrategytoimprovecrawl Mold doesnotnecessarilyhavetobecleaned Crawl Space? Existing MoldinMy Should ICleanUp greatly fromindividualtoindividual. condition. Humanreactiontomoldvaries can becomparedtoindicateadangerous on numericalstandardstowhichtestresults in themeasuredresults,thereisnoconsensus comprehensive enoughtoprovideconfidence Finally, evenifsamplingisdetailedand for speciation. trained specialistsanddonotgenerallyallow the mold.Thesetechniquesalsorequire presence ofmoldand,tosomeextent,identify of surfacesareothertechniquestoidentifythe T depending onthelabdoinganalysis. species, andgrowthconditionscanvary spore samplersmaybebiasedtowardssmaller to speciatethantotalsporecounts,butviable surroundings. “Viable”sporecountsareeasier simply reflectsthemoldpresentin building) orwhetherthemoldinbuilding ape liftsanddirectmicroscopicexamination C OMMON Q UESTIONS A BOUT M OLD An Introduction for the Southeast 61 ORG . CRAWLSPACES . WWW utilizes ductwork in the crawl space. utilizes ductwork in the clothes dryers in the living space. air and/or depressurize the crawl space. possible before beginning cleanup. insulation. Porous insulation that has been wetted should be replaced, since it will likely never recover its designed R-value, even when thoroughly dried. materials. Follow all manufacturers’ recommendations for application and safe handling. Swimming goggles can provide eye protection when working overhead. remediation, but simple advice is provided but simple advice is remediation, and References See the Resources below. of mold several published sources section for cleanup procedures. Energy During any cleanup, Advanced steps to help reduce recommends the following materials, mold toxins, the chance of cleaning or other mold spores, mold fragments, from the crawl space contaminants moving to the living space: that off any heating and cooling system • Turn • Reduce or stop the use of exhaust fans and • Pressurize the living area with HEPA-filtered Additional notes on cleaning mold: • Remove as much contaminated material as • Remove contaminated or damaged • Not all fungicides are effective on all contaminants in the crawl space can enter the in the crawl space can contaminants It is of the home by air transport. living area cleaned to help prevent new or also critical For becoming recontaminated. ducts from homeowner can additional protection, the the house with stand- upgrade air filtration in air handler/duct units or HEPA alone HEPA a fungicide over system filters, and/or apply short-term anti- the existing mold to provide level of continued fungal activity and some suppression. several reports Advanced Energy has received odors associated with of strong ammonia-like the drying-out in of existing crawl spaces North Carolina, which may be the result of the mold slowly dying or going dormant. The odors persisted for weeks or months without dissipating. Application of a fungicide in conjunction with reducing moisture levels has been reported to eliminate or prevent this problem. If a property owner does decide to clean up existing mold, work can range from spot cleaning of affected areas to comprehensive cleaning of most, if not all surfaces. Large jobs and time are likely too labor-intensive consuming to do as a home project. In these cases, property owners can contract for professional cleanup services water from damage or mold remediation companies. Building performance or other contractors may also offer this service. This guide is by no means a complete reference for doing safe and effective mold OLD M BOUT A private home inspectors prior to home private home causing more and more purchases is or to consider removing homeowners space. mold from their crawl “remediating” to choice of whether or not The homeowner’s on their level of clean up mold depends health impacts of concern about the potential or the impact on the leaving the mold in place specific benefit is that value of their home. One will make it easier cleaning out existing mold in the future. to detect a recurrence point in cleaning up Of course, there is no the moisture surface mold without improving conditions that allowed the mold to grow in the first place. The mold would simply grow back. Any activity to clean up surface mold should be part of an overall plan to close the crawl space permanently. Mold-contaminated ductwork also presents the question of whether to leave the mold in place, clean the ductwork, or replace the ductwork. Flexible duct and fiberglass-lined ductwork is verythoroughly difficult, if not impossible, to clean. Other options include leaving the duct as is, replacing the ductwork or spraying fungicides or encapsulating materials to isolate the mold in the duct from the air stream. Sheet metal ductwork is generally more feasible to clean and reuse without encapsulation. Advanced Energy recommends that you seal ductwork and seal holes between the house is and the crawl space whether or not the mold work reduces the cleaned up. This air-sealing chance that mold, mold byproducts or other UESTIONS Q OMMON C H 62 Closed Crawl Spaces IGH -P ERFORMANCE • Monitorandcontrolrelativehumidity below • Fungicidescanbeappliedaftercleaningto • Air-sealing andsubfloorrepairsareeasier • Replacethegroundvaporretarderaftera • Applicationofsealants,primers,andpaint • Pressurewashing,sandingorblastingwith • HEPA vacuumscanbeusedtocollect scrapingmay • Liquidcleaningordry • Chlorinebleachisnotalong-term growth recurring. 70% aftercleanuptoreducetherisk ofmold continued moldsuppression. removed andtoprovidesomelevelof encapsulate moldsporesthatwerenot while insulationisremoved. cleanup operation. cover stainsandresistbleed-through. topcoats mayberequiredtocompletely should beremovedafterwards. that mayremovestaining.Residualmaterials icearecleaningoptions baking sodaordry space floor. up debrisonsurfacesorthecrawl recommended insteadofsweepingtoclean surface moldremovedbyscraping,andare surface molds. not removeallstainingcausedby be producedinfatallevels. mix itwithammoniabecausetoxicgascan fungicide. Ifyouusechlorinebleach,never H OMES their immunesystemisnotfunctioning well. people becomecolonizedbymolds onlyif sometimes infectedbymolds,but generally, reacts topungencyandirritation.Peopleare endinginthebackofthroat, which nerve irritate mucousmembranesandthetrigeminal alcohols andsulfurcompounds,whichcan chronic exposures.Mostmoldsrelease more serious,chroniclungdiseasefrom A tinyfractionofallergysufferersmaydevelop eye irritation,sinusitis,anddifficultybreathing. events. Thesymptomscanincluderunnynose, health effectsareallergicreactionsandasthma infection, andtoxicity. Themostcommon exposure areoffourtypes:allergy, irritation, Health effectsgenerallyattributedtomold potential forsuchproblemsarebeneficial. problems, andstrategiesthateliminatethe for humanstoliveinhomeswithmoisture The bottomlineisthatitclearlylesshealthy the symptoms. in thesameconditionsisresponsiblefor or organism(forexample,bacteria)thatexists unclear whethermoldorsomeothersubstance like allergicrhinitisandasthma,howeveritis environments andoccupantmedicalconditions There isanassociationbetweendamphome mold growthinresidencesandhumanillness. documented acausalrelationshipbetween medical researchcommunitieshavenot At thetimeofthiswriting,scientificand People Sick? Does MoldMake are similar in toxicity to nerve gases. are similarintoxicitytonerve however, thetoxinsdoexistandsomeofthem understand therisksfrommycotoxinexposure, There isnotmuchhumandatatohelpus livestock eatmold-contaminatedmaterial. medicinewhen poisoning arefromveterinary best-documented casesofmycotoxin warfare betweenmicroscopiccreatures.The case, peoplearecollateraldamageinchemical with othermoldsorbacteriaforhabitat.Inthis likely toproducetoxinswhenincompetition mold species.Itisthoughtthatmoldsaremost They areproducedonlyoccasionallybysome from respirationandnutrientdecomposition. part oftheactliving,asarecompounds mycotoxins. Mycotoxinsarenotproducedas Some moldsproducetoxinscalled C OMMON Q UESTIONS A BOUT M OLD An Introduction for the Southeast 63 ORG . CRAWLSPACES . WWW oolBase Services (search for “mold” if necessary) U.S. Forest Products Laboratory www.fpl.fs.fed.us (search for “wood handbook”) National Association of Home Builders (NAHB) Research Center – T “Mold in Residential Buildings” http://toolbase.org/index-toolbase.asp ood moisture meters Delmhorst Wagner, Product/ServiceAnemometer/air flow meterBackflow dampersCarbon monoxide monitorsConstant airflow regulatorsDuct masticFlood vents (FEMA/NFIP-compliant)Fire-rated foam insulation TIF Fuel gas leak detectors Manufacturer/Provider High performance vapor retarder CO-Experts Liquid water alarms Smartvent, Inc. American Aldes Famco Mold sample analysisOutside air intake and filter housingRadon test kits and analysis (Thermax brand) Dow Chemical Sump pumps Raven Industries metersWireless Temperature/RH RCD Corp. S-Tech W Indoor Environmental Systems Basement Systems Environmental Microbiology Lab Labs AccuStar Oregon Scientific Systems Basement Products and ServicesProducts of products and services or providers is a list of the manufacturers The following used in discussed in this guide. Advanced Energy projects Florida Solar Energy Center (FSEC) www.fsec.ucf.edu “Florida Home Mold & Mildew Guide for Consumers” www.fsec.ucf.edu/bldg/science/mold Federal Emergency Management Agency (FEMA) www.fema.gov Bulletin 1-93, Openings in “Technical Foundation Walls” EFERENCES R ESOURCES AND EFERENCES Mold information www.cdc.gov/nceh/airpollution/mold Measuring air flow with plastic bags: Search for “garbage bag” Centers for Disease Control and Prevention (CDC) www.cdc.gov www.redcross.org/services/disaster/afterdis/ reptoc.html Canada Mortgage and Housing Corporation www.cmhc-schl.gc.ca/en/index.cfm www.acgih.org American Red Cross www.redcross.org Flooded Home” “Repairing Your Online Resources Online Resources of American Conference Governmental Industrial Hygienists R R Section 8 Section ESOURCES AND R H 64 Closed Crawl Spaces IGH -P ERFORMANCE Field StudyPilotReport: Davis, BruceandWilliamE.Warren. 2002. Environmental MicrobiologyLaboratory, Inc. The EnvironmentalReporterVolume 2,Issue5. Insight onTypes andRolesinWood Decay.” Burge. 2004.“Wood DecayingFungi–An Engineers. Atlanta,GA. Heating, RefrigerationandAir-conditioning 2005.AmericanSociety of Journal, January “Assessing MoldinBuildings”.ASHRAE Brennan, Terry andHarrietBurge.2005. Industrial Hygienists,Cincinnati,Ohio. control.” AmericanConferenceofGovernmental ACGIH, 1999:“Bioaerosols–Assessmentand T www.epa.gov/radon/ Radon information www.epa.gov/iaq/pubs/index.html#homes Indoor airquality www.epa.gov/iaq/molds/mold_remediation.html Commercial Buildings” “Mold RemediationinSchoolsand www.epa.gov/iaq/molds/moldguide.html Home” “A BriefGuidetoMold,MoistureandYour www.epa.gov Agency U.S. EnvironmentalProtection echnical References H OMES A fieldstudy crawl spacedesignandconstruction –a Rose, W. B. andA.TenWolde. 1994.Issuesin and Air-Conditioning Engineers. American SocietyofHeating,Refrigerating T Space MoistureControl.”In and Technical LiteratureRelatedtoCrawl Rose, W. B.1994.“AReviewoftheRegulatory Energy EfficientEconomy. W Energy EfficiencyinBuildings Proceedings ofthe1998SummerStudyon Penalties fromCrawlSpaceVentilation.” Hill, WilliamW. 1998.“MeasuredEnergy Environmental MicrobiologyLaboratory, Inc. Environmental ReporterVolume 2,Issue5. Ceratocystis/Ophiostoma (C/O)group.”The molds– “Fungi oftheMonth(II):Lumberyard Fallah, PayamandKamashRamanathan.2004. south. ventilated versussealedcrawlspacesinthe moisture performancecharacteristicsof A fieldstudycomparisonoftheenergyand Rose. 2002. Davis, Bruce,WilliamE.Warren andWilliamB. Raleigh, N.C.:AdvancedEnergy. versus sealedcrawlspacesinthesouth. performance characteristicsofventilated comparison oftheenergyandmoisture ransactions ashington, D.C.AmericanCouncilforan Raleigh, N.C.:AdvancedEnergy. , Vol. 100Pt.1.Atlanta,Ga. T echnology AssessmentReport: ASHRAE , Vol. 1. In Atlanta, Ga. Refrigerating andAir-Conditioning Engineers, number 3.AmericanSocietyofHeating, ASHRAE Technical DataBulletinvolume10, for ControllingMoistureinCrawlSpaces symposium summary. of Health. Environments and RemediationofFungiinIndoor NYCDOH, 2000. Medicine, NationalAcademiesPress. Indoor SpacesandHealth;Instituteof Spaces andHealth Institute ofMedicine,2004. Restoration Certification,Vancouver, Wash. Institute ofInspection,Cleaningand for ProfessionalMoldRemediationS520 IICRC. 2003. Other Resources Standard andReferenceGuide . NewYork CityDepartment R Guidelines onAssessment SUCSAND ESOURCES . CommitteeonDamp Recommended Practices Damp Indoor . , R EFERENCES An Introduction for the Southeast 65 ORG . ❸ CRAWLSPACES . ❻ WWW ❸ ❼ connections or seams within ten feet of an air handler unit. to register boots and seal the joint with mastic. Mechanically fasten the outer liner to the register the boot. Zip-tie connectors are typically used for mechanically attachments. drywall Seal joints or other paneling they penetrate. or gaps in the boot itself with mastic. filtering systems. condensate line penetrations, and any unused holes in the air handler permanently. ❼ 3. Embed fiberglass mesh tape in the mastic at 3. Mechanically fasten the inner liners of flexible ducts 4. Seal duct register boots with mastic to the subfloor, 5. Gasket or tape access panels for the air handler or 6. Seal permanent panels, electrical, refrigerant and 7. ❻ ❻ ❸ ❸ ❼ duct system with duct mastic connections or seams with gaps larger than 1/8 inch. Sealing ductwork for forced-air heating and cooling improve systems is one of the most effective ways to If energy efficiency and indoor air quality in a home. you have any gas-fired or other fuel-burning building appliances in the home, you should contact a performance professional to assess whether duct It is sealing will cause a combustion safety problem. in ideal to contact a building performance professional any case, so that any necessary to the duct changes so that system can be implemented before sealing, and safety the duct tightness improvement and combustion can be verified after the sealing work is complete. Sealing ducts involves the following steps: Seal all permanent connections or seams in the 1. Embed fiberglass mesh tape in the mastic at 2. ❺ VERVIEW EALING ❶ S ❷ O ❹ ❹ UCT UICK ❹ ❶ D ❶ ❺ ❺ A Q Appendix A Appendix OF PPENDICES A H 66 Closed Crawl Spaces IGH -P ERFORMANCE calculating thedewpointtemperatureofair industries. Itisincludedasatoolfor in therefrigerationandair-conditioning complex psychrometricchartstypicallyused This chartisasimplifiedversionofthe C P S Appendix B HART SYCHROMETRIC IMPLIFIED 20 25 H 30 30 OMES 35 40 Temperature (°F) Dew Point 40 45 Sensible Temperature (°F) 50 50 55 60 60 65 B of thechart. leftside temperature isreadalongthecurved in thecenterofchart.Dewpoint lines Relative humidityisplottedonthecurved would getfromastandardthermometer. of thechartandistemperaturereadingyou bulb” temperature)isreadonthebottomscale Sensible temperature(alsoreferredtoas“dry air temperaturechanges. point temperatureorrelativehumiditywhenthe known, andforpredictingchangestodew when temperatureandrelativehumidityare 70 70 75 C 80 80

90% A 70% 90 50%

30%

100 10% RH the relativehumidityofthisairwouldbe90%. Fsensibletemperature, C indicatesthatat73° temperature. Forexample,goingrighttopoint line upverticallywiththedesiredsensible temperatures, gorighthorizontallyuntilyou relative humidityofthisairatdifferent F. To findoutthe dew pointtemperatureis70° of thechartatpointB,whichindicatesthat the dewpointtemperaturescaleonleftside temperature, golefthorizontallyuntilyoureach determine thecorrespondingdewpoint atpointA.Torelative humiditycurve, until youreachtheintersectionwith60% the bottomofchart,thengoupvertically Fonthesensibletemperaturescaleat Find 85° Fand60%relativehumidity. conditions of85° As aquickexample,saythatyouhaveair A PPENDICES An Introduction for the Southeast 67 ORG . CRAWLSPACES . WWW For example, if you were to measure wood moisture if you were to measure For example, in a 70°content of 18% then you can F crawl space, to relative the wood has been exposed estimate that recent days or approximately 85% over humidity of humidity at the time of your weeks, even if the relative lower due to drier outside measurement is much conditions. space is vented with outside air, Note that when the crawl the crawl space can change relative humidity inside periods of time. In some significantly over short of relative humidity and wood situations, measurements still appear to be contradictorymoisture content may data from the table. The even when using the equilibrium space more controlled conditions in a closed crawl generally make it easier to interpret measurements. aking a single-point measurement of either wood measurement aking a single-point T in a crawl space or relative humidity moisture content of the long-term a complete picture may not provide space. Relative inside the crawl moisture conditions humidity can vary much more quickly than wood wood moisture content readings moisture content, and by the presence of can be dramatically increased on the surface of the wood. intermittent condensation wood moisture content and The table below relates long-term conditions of relative ambient temperature to content and If you can measure wood moisture humidity. can use this table to then ambient temperature, you relative humidity that the wood estimate the long-term content has been exposed to. Note that wood moisture varies only slightly (0.5% to 1.2%) at a particular from 40° relative humidity over the range of temperature F to 90° F. (Source: U.S. Forest Products Laboratory, Wood Handbook, Table 3-4.) Wood Handbook, (Source: U.S. Forest Products Laboratory, Moisture content of wood in equilibrium with stated temperature and relative humidity Moisture content of wood in equilibrium OISTURE M 10 50 7.9 8.7 9.5 10.3 11.2 12.3 13.4 14.8 16.4 18.4 20.9 24.3 °C °F 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 4.4 40 7.9 8.7 9.5 10.4 11.3 12.3 13.5 14.9 16.5 18.5 21 24.3 15.621.1 6026.7 7032.2 80 7.8 90 7.7 8.6 7.4 7.6 8.5 9.4 8.1 8.3 9.2 10.2 8.9 9.1 10.1 11.1 9.7 9.9 11 12.1 10.5 10.8 13.3 12 11.5 11.7 14.6 13.1 12.6 12.9 16.2 14.4 13.9 14.2 18.2 16 15.4 15.7 20.7 17.3 17.9 17.7 24.1 19.8 20.5 20.2 23.3 23.9 23.6 Temperature content (%) at various relative humidity values Moisture OOD UMIDITIES IFFERENT ELATIVE ONTENT AT EMPERATURES AND H D T R W C Appendix C Appendix PPENDICES A H 68 Closed Crawl Spaces IGH -P ERFORMANCE G Appendix D FHA –FederalHousingAdministration FEMA –FederalEmergencyManagementAgency EPDM –Ethylenepropylenedieneterpolymer EPA –U.S.EnvironmentalProtectionAgency DOE –U.S.DepartmentofEnergy CO –carbonmonoxide unit CMU –concretemasonry CDC –CentersforDiseaseControlandPrevention CAR –constantairflowregulator BTU –Britishthermalunit ASTM –AmericanSocietyforTesting andMaterials Conditioning Engineers ASHRAE –AmericanSocietyofHeating,RefrigeratingandAir- ARI –AirConditioningandRefrigerationInstitute AE –AdvancedEnergy ACGIH –AmericanConferenceofGovernmentalIndustrialHygienists ACCA –AirConditioningContractorsofAmerica OSR OF LOSSARY H OMES A RNM AND CRONYMS A BBREVIATIONS TIF –ThermalIndustriesofFlorida, Inc. SFHA –SpecialFloodHazardArea SEER –SeasonalEnergyEfficiencyRatio OSHA –OccupationalSafetyandHealthAdministration ORNL –OakRidgeNationalLaboratory NFIP –NationalFloodInsuranceProgram NBS –NationalBureauofStandards NAHB –NationalAssociationofHomeBuilders Device MADD –MoldAmplificationandDelivery IRC –InternationalResidentialCode Code IECC –InternationalEnergyConservation ICC NER–InternationalCodeCouncilNationalEvaluationReport HVAC –Heating,Ventilation andAirConditioning HSPF –HeatingSystemPerformanceFactor HEPA –High-EfficiencyParticulateArrestance FSEC –FloridaSolarEnergyCenter A PPENDICES An Introduction for the Southeast 69 ORG . CRAWLSPACES . WWW systems 41–42; code officials and, 20; combustion safety, 15; components of, 2, 7; construction sequence, 23; converting 36–38; contracts and pricing for, wall-vented spaces to, 45–48; defined, 1; designs 16 42; humidity 2, 19–20, 25, 28–35; fire safety, for, (See control, 25–27; installing, 2, 19, 40; insulation insulation); job-site logistics, 20–22; maintenance, 22, 48; moisture management, 7–13; pest control, 13–14; Princeville research project, 49–57; quality 17, 43, 56, 63; assurance, 22–23; radon safety, 20 unregulated specifications, 42-43; training labor, blown insulation, 16 blown insulation, 59–60 blue stain fungi, symbol, 36 blue water drop 47 boilers, 15, 49 Brennan, Terry, builders, 2, 40 building codes, 19, 39–42 building scientists, 40 Burkard samplers, 56 51 butterfly dampers, 25, 45 cabinetry, callbacks, 23 capillary See wicking action. capillary28–35 breaks in specifications, carbon monoxide, 15, 47, 63 conditioning central air conditioning, 25, 26. See also air 20, 38 certificates of occupancy, check valves, 12 chemical storage, 47 chlorine bleach, 62 cleaning mold, 47, 60–62 climate, 4–5, 57 closed crawl space installers, 2, 19, 40 39–43, closed crawl spaces: building code changes, "closed with a sealed liner" crawl spaces, 1 Conditioning Engineers (ASHRAE), 49 Engineers (ASHRAE), Conditioning 42, 47; in air supply, backdrafts, 43, 47; combustion 28–35; direct-vent fuel- crawl space specifications, 43, 47; discharge piping burning appliances, 15, oil-fired, 15, 15; gas- or and drains, 13; drafts for, appliances, 15, 47; sealing 42, 43, 47; natural draft ducts, 65 Moisture in Crawl Spaces, 49 American Society for Testing and Materials (ASTM), 42, 51 and Materials (ASTM), for Testing American Society and Air- of Heating, Refrigerating American Society ammonia, 62 61 ammonia-like odors, 47, Anderson samples, 56 anemometers, 25, 63 draft appliances, 15, 47; appliances: atmospheric asbestos, 43, 47 ASHRAE Recommended Practices for Controlling asthma, 60, 62 ASTM E 84 standard, 51 ASTM E 152 standard, 42 atmospheric draft appliances, 15, 47 backdraft dampers, 25, 42 backdrafts, 43, 47 backflow dampers, 25, 63 backflow valves, 12, 36 baking soda treatments, 62 balancing dampers, 25, 51 band joists, 9, 14, 16, 42, 51 basements, 40 bathroom vents, 13, 28–35, 37, 46 batt insulation, 14, 16, 47, 51 batteries, 22, 48 63–64 bibliography, Energy Services,Bill Warren 49 bioaerosol sampling, 49, 60 bleach, 62 blocking sources of moisture, 8–12 40; building codes, 41; closing during construction, 40; building codes, 41; spaces, 38; in crawl space 37; in converted crawl 65; inspecting designs, 28–35; to ductwork, 8 22, 48; protecting from runoff, annually, retarders recommendations, 1, 49–57; sealed vapor 7 12; symbols in recommendations, 41; humid air, combustion air supply); house air, preventing, 9–10; mold spore content, 49, 56–57, 66; 59, 60; properties of, 4; psychrometric charts, temperature, 51–52, 66 41; combustion air (See combustion air supply); 41; humidity control in crawl spaces, 13, house air, 25–26, 28–31; in research houses, 51 Hygienists (ACGIH), 60 abbreviations, 68 abbreviations, See also dew point absolute moisture, 52–54. to basements or other structures, access doors or panels: acronyms, 68 research, 3; Princeville project, Advanced Energy: future supply); combustion air (See air: air supply (See air Air Conditioning Contractors of America, 4 55 air conditioning systems, 25–26, 28–31, 46, air filtration, 61, 63 42 air flow, air flow meters, 25, 63 air flow regulators, 25, 26, 63 air intake housings, 63 air leakage, 10, 49 air pressure, 26, 42, 50, 61 walls, 2 air-sealed codes, 39, air supply: air intake housings, 63; in building alarms. See monitors and alarms allergies, 60, 62 ambient temperature, 67 American Conference of Governmental Industrial Index NDEX I H 70 Closed Crawl Spaces IGH -P ERFORMANCE customizing crawlspacedesign,19–20 crawl spaces,1;buildingcodechanges,39–43; costs ofclosedcrawlspaces,20,23 cosmetic problemsfromdampness,45,53 coordinating schedules,20–21 cooling equipment.SeeHVAC equipment conversions toclosedcrawlspaces,21,45–48,50–51 conventional wisdom,crawlspacesand,20 contracts forcrawlspaceinstallation,23 contractor damagetovaporretarders,22,48 construction process,21–22,36–38 constant airflowregulators,25,26,63 conditioned spaces,41–42 conditioned crawlspaces,1 conditioned air:inbuildingcodes,39,41;humidity condensation: incrawlspaces,2,4,46,50; condensate drainpans,13,28–35,37,40,46 composite materials,60 complex homedesigns,3,21,36 comfort levels,55-56 combustion airsupply, 15,42,43,45,47,65.Seealso code officials,2,20,39–40 exhaustvents,13,28–35,37,40,46,61 clothes dryer closed-cell foaminsulation,16 also closedcrawlspaces;wall-vented crawlspaces raising abovegrade,8;websiteinformation,1.See Princeville researchproject,49–57;problemsin,2; 26; firehazardsin,16;maintenance,22,48; conventional wisdomand,20;ductworkschematics, systems research houses,51.Seealsoairconditioning control incrawlspaces,13,25–26,28–31; research studies,53;watervaporand,4 dehumidifiers and,27,32–35;inPrinceville air supply H OMES ductwork: conditionedairfrom,13, 25–26,28–31; duct mastic.Seemastic 45,53 drywall, systems,13 drying outcrawlspaces,4,45,47, 51, 53,61 drying exhaustvents vents.Seeclothesdryer dryer rot,59 dry icetreatments,62 dry bulbtemperature,66 dry air,dry 25–26 dried-in phaseofconstruction,22,37 drawings forcrawlspaces,25,28–35 drains anddrainage:forappliances,13;inclosedcrawl drafts forcombustionappliances,15,47 dormant mold,60–61 doors. Seeaccessdoorsorpanels direct-vent appliances,15,28–35,43,47 dew point,4–5,52–54,55,66 detectors. Seemonitorsandalarms designs forclosedcrawlspaces,19–20,25,28–35 depressurization systems,17 dehumidifiers: advantagesanddisadvantages,27;in decks, 9 debris, 40,46–47 Davis, Bruce,49 data collectioninresearch,51–52 Dastur, Cyrus,49 darkness, moldgrowthand,59 damp-proofing foundations,8,28–35,40 leakage in,50;mold-contaminated, 61;reducing spaces, 45 drain pipes,8;forsurfacewater, 8;inwall-vented 8, 28–35;inspecting,22;sizing,42;sub-surface spaces, 2,12,13,28–35,36,40;foundationdrains, construction installation,21,37 inspecting, 22;installing,13;temporary building code,41;crawlspacedesignsfor, 32–35; flow hoods,25 floor platformphaseinconstruction, 37 floor joists,28–35 floor insulation,2,28–29,32–33, 54,57 flooding, 9,10 flood vents,9,10,28–35,40,63 float-kill switches,13 flashing, 8 fireblocking, 16 fire ratings,14,16,42,63 fire hazards,16 filtering air, 61,63 field studies.SeePrincevilleresearchproject fiberglass meshtape,11,38,51,65 fiberglass insulation,16,40 Federal HousingAdministration,39 Federal EmergencyManagementAgency(FEMA),9,10 fans, 41,43,61 false positiveornegativetests,60 Mutual4880standard,42,51 Factory faced battinsulation,14 exterior watermanagement:inclosedcrawlspaces,2; exhaust fans,41,43,61 evaporation, 10–12,48 Environmental ProtectionAgency(EPA), 17 envelope leakage,50 energy savings,1,20,51,54–55,57,65 elevation certificates,10 electricity submeters,51 electrical outlets,32–35,37 dust, moldcountsand,57 40, 45;surfacewater, 8 roof runoff,8,28–35,37,40;sitegrading,20, 40, 46,65;testing,49 leakage, 50;schematics,26,65;sealing,9,28–35, I NDEX An Introduction for the Southeast 71 ORG . CRAWLSPACES . WWW building codes, 39, 42; climate and, 57; in closed 39, 42; climate and, building codes, crawl spaces, 1; crawl spaces, 16; in conditioned 10; 16, 42; on flood vents, fire ratings and safety, 32–33, 54, 57; installing floor insulation, 28–29, L-shaped method, 39; during construction, 37; and, 61; pest moisture in, 2; mold cleanup Princeville research project, inspection and, 14; in houses, 51; sample 54; replacing, 47; in research construction, 21; installations, 28–35; scheduling 34–35, 42, 54, 57; in wall- wall insulation, 30–31, vented crawl spaces, 41 (ICC NER), 16 48 59; removing, 12–13; standing water, inspection gaps, 28–35, 39, 51 inspection gaps, 51–52 in research project, instrumentation joists, 14; in attachments, 42; on band insulation: insulation contractors, 19 Report International Code Council National Evaluation International Energy Conservation Code, 20, 39 39 International Residential Code (IRC), 16, 17, interviews with property owners, 49 irrigation systems, 8, 21, 45 irritation, from mold, 62 isolating crawl spaces, 46 job-site logistics, 20–22 joints, 9, 11 Karagiozis, Achilles, 49 kitchen vents, 13, 28–35, 37, 46 L-shaped method of insulating, 39 training, 20 labor, landscaping, 8, 21 lapping seams, 11 leakage, 45, 49, 50 liquid water: alarms, 13, 22, 47, 63; mold growth and, 61 61 closed crawl spaces and downsizing, 12, 25; heating- or cooling-based climates, 57; in research houses, 50; sealing, 65 27; hidden or obstructed areas, 13–14; by pest management professionals (See pest management); wall-vent conversion projects, 46 38; post-occupancy, hardwood floors, 45, 53 hardwood floors, 22, 47, 48 hazardous materials, of mold, 60-61, 62 health impacts 50 heat pumps, equipment HVAC heating equipment. See 57 heating-based climates, Particulate Arrestance), 20, filters (High-Efficiency HEPA and, 13–14 hidden areas, pest inspections 17 High Radon Potential counties, filters, 20, Arrestance (HEPA) High-Efficiency Particulate retarders, 63 high-performance vapor 10 hollow block foundations, home inspectors, 3 home performance contractors, 19 41 house air, house exhaust fans, 43 house leakage, 50 9–10, 25–27, 55. See also relative humidity humidity, contractors, 19 HVAC equipment: activating, 38; average use, 54–55; HVAC hygrothermal modeling, 57 ignition barriers, 16, 42 50–51 improving wall-vented crawl spaces, 45–48, induced-draft combustion systems, 47 infection, from mold, 62 initial costs, 23 insect pests. See pest management inspection: closed crawl spaces, 22, 48; dehumidifiers, 40; pitch of, 42; site grading, 8, 28–35, 36, 40, 45 40; pitch of, 42; site grading, 8, 28–35, 36, 40, existing crawl spaces, 50; installing during construction, 37–38; mold cleanup and, 62; 50, preventing evaporation, 10; in research houses, 51; securing, 12, 42; in wall-vented crawl spaces, 46, 52 8; drain systems, 8, 28–35, 40, 45; hollow block, 8; drain systems, 8, 28–35, in construction, 36–37; 10; moisture management 19; scheduling repair/waterproofing contractors, gaps, 9; waterproofing, 8, construction, 20; sealing 28–35, 45 gravel beds, 8 12 ground: evaporation from, 10–12; gases in soil, 41; in ground vapor retarders: in building codes, 39, 8 groundwater, guarantees (warrantees), 14, 20, 21, 22, 23, 38, 47 gutters, 8, 21, 40 garages, 40 gases in soil, 12 65 gas-fired appliances, 15, 28–35, 42, 43, 47, gaskets, 9, 37, 65 gasoline, 16, 22, 47, 48 general contractors, 19 GFCI-protected outlets, 32–35, 37 28–35, 36, grading: costs and, 23; in crawl spaces, 12, flow rates, specifying, 42 flow rates, specifying, 42, 51 FM 4880 standard, 14, 16, 42, 51, 63 foam insulation, 65 forced-air heating, design and, 2; damp-proofing, foundations: crawl space freezing pipes, 54 15, 28–35, 42, 43, 47, 65 fuel-burning appliances, 15, 63 fuel-gas leak detectors/alarms, fungi, 59, 60 fungicides, 47, 61, 62 furnaces, 15, 28–35, 42 NDEX I H 72 Closed Crawl Spaces IGH -P ERFORMANCE mold: cleaningup,47,60–62;incrawlspaces,4,20,50; moisture management:blockingsourcesofmoisture,2, moisture levels:comfortand,55-56;moldgrowth Model EnergyCode,20 systems,2,13 mechanical drying mechanical contractors,19,21 mechanical attachmentofvaporretarders,10,11,42,51 measuring crawlspaces,49 mastic: inbuildingcodes,40;constructionphase,38; masonry, 16,20 manufacturers, 63 make-up air, 43 maintenance: closedcrawlspaces,22,38,48; main constructionphase,37 Lstiburek, Joe,49 low-volume construction,3,36 low indoortemperatures,46 long constructionschedules,21,36 logistics ofcrawlspacejobs,20–22 local codeofficials,20 counts, 49,56–57,59,60;stirring upsettleddust, research studies,54,56–57;speciating, 60;spore odors and,47;photographs,5;in Princeville and, 43;growthof,2,59;healthimpacts, 60-61,62; debris and,46–47;dormancy, 60–61;exhaustair moisture, 12–13 construction, 21–22,36–38;overview, 7;removing spaces, 7–13;compromising,17;during 8–12; inbuildingcodes,41–42;closedcrawl spaces, 45 research project,1,52–54;inwall-ventedcrawl 59; passiveventilationand,4;inPrinceville sealing vaporretarders,11 63; inresearchhouses,51;sealingductwork,65; in crawlspacespecifications,28–35;manufacturers, dehumidifiers, 27;reductionsin,23 H OMES packaged unitequipment,9 p-traps, 12 outside sourcesofmoisture,8–12 outside air, 4,26 organic material,40 oil-fired appliances,15,28–35,42,43,47,65 odors, 47,61 occupant requirements,20,54–55 obstructed areas,inspectionsand,13–14 Oak RidgeNationalLaboratory, 57 North CarolinaSolarCenter, 49 North CarolinaResidentialCode,1–2,7,16,39–43, North CarolinaMechanicalCode,15 North CarolinaDepartmentofInsurance,40 North CarolinaBuildingCodeCouncil,40 North Carolina,climateof,4–5 non-porous insulation,16 negative airpressures,26 natural gasalarms,15 natural draftappliances,15,47 National FloodInsuranceProgram,10 National BureauofStandards,39 mycotoxins, 62 movement ofvaporretarders,11,12 monitors andalarms:aftermoldcleanup,62;annual mold sampleanalysis,63 50–51 for temperature,47 Princeville researchproject,51–52;forradon,56; during construction,22;manufacturers,63;in for humidityandmoisture,13,22,46,47;installing 22;forcarbonmonoxide,15; monitoring services, against, 23 57; tests,21,60;typesof,59–60;warranties Princeville researchproject,1;dew pointconditions,5; primers, 62 pricing installationofcrawlspaces,23 pre-treatment forpests,14,21 pressure washing,62 pressure reliefvents,42 pressure reliefpipes,28–35,37,40 pressure effects:moldcleanupand,61;negative post-occupancy maintenance.Seemaintenance porous insulation,47 porches, 9,40 pony walls,16 polyisocyanurate foam,51 polyethylene vaporretarders,10,40.Seealso plumbing leaks,45 pitch ofgrade,42 pipes: appliancedischarge,13;freezing,54;sub-surface piers, 23,37 Piedmont region,NorthCarolina,49–50 pest management:buildingcodesand,40;closedcrawl perimeter walls:costsofcrawlspacesand,23; penetrations: firesafetyand,16;insampledesigns, passive ventilation,2,4 paint topcoats,62 setup, 50–51;implicationsof,57; instrumentation energy performance,54–55;field studyexperiment pressures, 26;testing,50 retarders drains, 8;temperature/pressurerelief,28–35,37,40 scheduling, 21;warranties,20,47 hidden areas,13–14;professionals,19,20,40,47; inspection gaps,28–35,39,51;liabilitiesand spaces and,13–14;crawlspacedesigns13; pest inspectionand,14 evaporation from,10–12;insulation,16,39,51; 36 28–35; sealing,9,36,40,46;water-tightness and, I NDEX An Introduction for the Southeast 73 ORG . CRAWLSPACES . WWW spaces, 45; in closed crawl spaces, 12, 40; in crawl spaces, 45; in closed crawl spaces, 12, 40; in 13; space specifications, 28–35; discharge drainage, 37; inspecting, 22; manufacturers, 63; pits for, ratings, 42; in retrofits, 47 dew point); low indoor temperature, 46; monitors, 47, 63; in Princeville research project, 54; sensible temperature, 66; wood moisture levels and, 67 enWolde, Anton, 49 Anton, enWolde, supply air. See air supply; combustion air supply supply air. supply plenums, 42 surface mold, 61 8 surface water, symbols in recommendations, 7, 36 62 symptoms of mold-related illnesses, 60-61, tape joints, 11 tears in vapor retarders, 11 point (See temperature: air temperature, 4–5, 51–52; dew 40 temperature/pressure relief pipes, 28–35, 37, temporary vapor retarders, 37 tension wires, 47 T sprinkler systems, 8, 45 sprinkler systems, Stachybotrys species, 59-60 43 stack effect, 62 stains, mold, 20, 40 stamped letters of approval, spaces, 19 standards for closed crawl standby air leakage, 10 See liquid water standing water. Straube, John, 49 structural damage, 46 37, 62 subfloors, 9, 16, 21–22, systems, 17 sub-membrane depressurization systems, 17 sub-slab depressurization 8 sub-surface drain pipes, summer temperatures, 4–5 sump pumps: activating, 38; adding to wall-vented 16, 42; radon safety, 17, 43, 56, 63; symbols in 17, 43, 56, 63; symbols 16, 42; radon safety, recommendations, 7 gaps in foundations, 9; vapor retarders, 11, 12 return plenums, 42 return plenums, 12 reverse flow, 14 rigid foam insulation, 16, 40 rock wool insulation, 37, 40 roof runoff, 8, 28–35, Rose, William, 39, 49 rot, 2, 5, 46, 59 37, 40 runoff systems, 8, 28–35, 15; fire safety, combustion safety, safety considerations: sanding, 62 sap stain fungi, 59–60 scheduling projects, 20–22, 36 sealants, 9, 37, 62 sealed crawl spaces, 1 65; sealing: details in specifications, 28–35; ductwork, seams, 11, 38 seasonal climate changes, 26, 27, 53, 54–55 sensible temperature, 66 SFHA (Special Flood Hazard Area), 9, 10 signs, 22, 38 sill plates, 9, 14, 28–35, 37 site conditions, 19–20 site grading, 8, 20, 40, 45 equipment, 12, 25 sizing: drains, 42; HVAC software, 20, 57 solvents, 16, 22, 48 sources of moisture, blocking, 8–12, 45–46 southeastern United States climate, 2 Southface North Carolina, 49 Special Flood Hazard Area (SFHA), 9, 10 spore counts, 49, 56–57, 60 spores, 59 spot cleaning mold, 61 Crawl Spaces, 49 growth and, 59; monitors, 13, 47, 63; psychrometric charts, 66; spring and fall seasons, 26; 2, understanding, 4–5; in wall-vented crawl spaces, 52–54; wood moisture levels, 67 and data collection, 51–52; moisture performance, 51–52; moisture and data collection, 3; sampling, 56–57; photographs, 52–54; mold 49–50; radon existing crawl spaces, quantifying 5, 54 56; temperature conditions, measurements, condensate, 27; sump spaces, 2; for dehumidifier pumps (See sump pumps) references and resources, 63–64 52–54; mold relative humidity: in closed crawl spaces, 1, removing moisture, 12–13 repair kits, 22 repairing structural damage, 46 replacing insulation, 47 49–57 research implications of Princeville project, 1, resources and references, 63–64 respiratory hazards, 20, 57, 62 retrofits. See conversions return air ducts, 41 radon safety, 17, 43, 56 radon safety, radon test kits, 63 rain, 4, 21, 45, 50 in Recommended Practices for Controlling Moisture private home inspectors, 3 private home inspectors, 40, 63 product manufacturers, 19 professional engineers, propane alarms, 15 38, 48, 49 property owners, 3, 19, 11, 38, 41 protecting vapor retarders, 4, 5, 66 psychrometric charts, 13; in closed crawl pumps: for appliance drainage, quality assurance, 22–23 NDEX I H 74 Closed Crawl Spaces IGH -P ERFORMANCE wall insulation:attachments,42;climate and,57;in wall evaporation,10–12 volunteer-built homes,21 visible mold,60 viable sporecounts,60 vents, 42,45.Seealsofloodvents;wall-ventedcrawl ventilation openings,41 ventilation fans,5 vent dams,41 vapor retarders:inbuildingcodes,40,41;closed vacuums, 62 U.S. DepartmentofEnergy, 49 unvented crawlspaces,1,39 LaboratoriesUL1715standard,42 Underwriters LaboratoriesUL1040standard,42 Underwriters two-pipe fuel-burningappliances,15,28–35,43,47 training needs,20 toxicity ofmold,62 tiger teeth,47 Thomann, Wayne, 49 thermostat settings,54,55-56 thermal performance,50 thermal insulation,16,42 thermal barriers,16,42 testing: crawlspacedesigns,3;mold,60;vapor woodand,54; termites: crawlspacedesigns,13;dry spaces installation, 37 construction sealing, 12,28–35;temporary inspection and,14;protecting,11;repairkits,22; inspecting, 22,48;manufacturers,63;pest crawl spaces,2;groundandwall,10–12; retarders, 12 inspection gaps,14,28–35,51 H OMES wood moisturemeters,63 wood moisturelevels,2,4,51,52–54,67 wood: cabinetry, 45;perimeterwalls,16;rotincrawl wireless meters,63 wicking, 8,12,14,30–31 wet bulbtemperature,66 web sites:resources,63–64;www.crawlspaces.org, 1,40 weather strips,10 waterproofing foundations,8,28–35,45 water vapor, 4,12–13 water heaters,15,28–35,37,42,47 water dropsymbolinspecifications,36 water alarms,22 water. Seeliquidwater;watervapor Wa warranties, 14,20,21,22,23,38,47 wall-vented crawlspaces:inbuildingcodes,40,41; wall vaporretarders,10,11,36,37,42 rren, Bill,49 space framing,2,4,5,46,59;trimcarpentry, 45,53 relative humidityin,2 with moisture,2;quantifyingforresearch,49–50; Princeville researchproject,1,49–57;problems 46; moldin,56,59;passiveventilationand,4; converting toclosed,45–48;isolatingfromhouse, project, 54 during construction,37;inPrincevilleresearch crawl spacespecifications,30–31,34–35;installing I NDEX

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