Executive Summary ...... 2 Position Statement for the Wallcoverings Association and the Chemical Fabrics & Film Association Regarding the Relationship Between Mold and Mildew and Wallcoverings ...... 3 Introduction ...... 4 Section 1. Who, What, Where, When, Why’s of Mold ...... 5 1.1. Mold Growth and Health Effects: It’s Not That Simple ...... 5 1.2. Overview of Mold in Building and Home Interiors ...... 6 1.3. Wallcoverings and Mold: A Function of Moisture Levels and Permeability ...... 11 1.4. Mold, Mildew, Fungi – What’s The Difference ...... 16 1.5. Different Types of Indoor Molds ...... 18 1.6. Are Molds Really Toxic? ...... 19 Section 2. How to Tell if a Mold Problem Exists ...... 23 2.1. Finding a Qualified Expert ...... 23 2.2. What the Expert Will Do to Assess the Problem ...... 23 2.3. Testing Criteria and Results...... 28 Section 3. How to Get Rid of Mold ...... 31 3.1. Cleaning, Removing Building Materials ...... 31 3.2. Specific Personal Protection and Containment Guidelines...... 34 3.3. Verifying Successful Remediation...... 35 Section 4. How to Keep Mold From Growing ...... 36 4.1. Eliminate Sources of Moisture ...... 36 4.2. Select Materials and Finishes to Prevent Mold ...... 40 4.3. Proper Surface Preparation...... 41 4.4. Good Practices – Keep Materials and Work Area Clean ...... 43 4.5. Design and Build It Right in the First Place ...... 45 Appendix A. List of Guidelines and Resources for Assessment and Remediation of Mold Contamination ...... 48 Appendix B. Description of Wallcoverings ...... 50 Appendix C. MOIST Personal Computer Model ...... 53 Appendix D. Standard Test Method and Calculation of Permeability as Prescribed in ASTM E 96-95, Standard Test Methods for Water Vapor Transmission of Materials...... 56 Appendix E. Frequently Asked Questions ...... 58 Appendix F. Glossary...... 63 References ...... 66 Index...... 70 Executive Summary

In response to concerns about mold growth in building The Chemical Fabrics & Film Association is an internation- and home interiors, the Wallcoverings Association (WA) al trade association representing manufacturers of poly- and the Chemical Fabrics & Film Association (CFFA) offer mer-based fabric and film products used in building and this review of a variety of scientific, technical, and med- construction, automotive, fashion and many other indus- ical resources to answer questions and to educate read- tries. Chemical fabrics and films can be found in hun- ers about the complex and often controversial issues dreds of applications, including commercial and residen- surrounding mold growth in homes and buildings, partic- tial wallcoverings; automotive upholstery, instrument and ularly with respect to wallcoverings. The publication also door panels, and convertible tops; upholstery for furniture; discusses various strategies for minimizing or eliminating and home décor. the potential for mold growth, by abolishing the moisture source, by carefully selecting wallcoverings, by taking Please see the next page for the WA’s and CFFA’s position into account the climate and design features of homes statement on the relationship between mold, mildew and and buildings, and by adhering to good practices in wallcoverings. An overview of mold and mildew as it preparing wall surfaces and installing wallcoverings. relates to chemical and film products also is available It concludes with a discussion of why homes and build- from CFFA. ings fail and a summary of a model of how to prevent and solve problems, such as mold and mildew growth, To obtain additional copies of this publication or to learn at each stage of the design and construction process. more about the Wallcoverings Association, please contact:

Although they are often cited in connection with mold Wallcoverings Association and mildew growth in building interiors, wallcoverings do 401 N. Michigan Avenue; Chicago, Illinois 60611 not cause mold to grow. In virtually all cases, the mold Phone (312) 644-6610 Fax (312) 527-6705 and mildew is due to excessive moisture. To prevent or www.wallcoverings.org eliminate mold, the source of the moisture must be identified and eliminated. If the moisture source is not found To obtain a copy of this publication, CFFA’s Mold & and corrected, mold will continue to grow. Mildew: An Overview/Wallcovering or learn more about the Chemical Fabrics & Film Association, please contact: This publication is intended for the wallcoverings industry, including manufacturers, distributors, professional Chemical Fabrics & Film Association installers, interior designers, building owners and man- 1300 Sumner Avenue; Cleveland, Ohio 44115-2851 agers, homeowners, and end users. It is not intended to Phone (216) 241-7333 Fax (216) 241-0105 provide design guidance or to serve as a training manual www.chemicalfabricsandfilm.com for mold assessment and remediation. The goal is to provide readers with an understanding of the state of the Also, please visit the WA or the CFFA’s websites science so they can be better equipped to prevent mold for updates/errata to this document. problems, handle mold complaints when they do occur. Every effort has been made to equally represent com- The Wallcoverings Association and the Chemical Fabrics mercial and residential wallcovering products. & Film Association gratefully acknowledge the generous contribution to this publication by the Foundation of the The Wallcoverings Association is an industry organization Wall and Ceiling Industry (FWCI), whose publication, dedicated to promoting the best interests of the industry Mold: Cause, Effect and Response, was used as source and its end users and serving as a conduit for ongoing material in the development of this publication. To communications for and between all business segments. obtain a copy of this publication or learn more about To that end, the WA stays abreast of current topics of FWCI, please contact: concerns impacting the wallcoverings industry and provides sound information on products, services and Foundation of the Wall and Ceiling Industry issues to architects, designers and end users to support 803 West Broad Street, Suite 600; Falls Church, VA 22046 the choice of wallcoverings as a viable, cost-effective Phone (703) 534-8300 Fax (703) 534-8307 decorating option. www.awci.org

2 Position Statement for the WA and CFFA Regarding the Relationship Between Mold and Mildew and Wallcoverings

The Wallcoverings Association (WA) and the caused by mold is an indication of a moisture Chemical Fabrics & Film Association (CFFA) rec- problem. The WA and CFFA recommend that the ognize that issues concerning mold and mildew source of the water or excessive moisture should are gaining increased attention from both residen- be found immediately and eliminated. The control tial and commercial property owners as well as of moisture vapor and its relationship to different the public at large. Although wallcoverings are types of wallcovering construction must be com- often cited in connection with mold and mildew municated to specifiers, installers, architects and growth, it must be understood that wallcoverings property owners. do not cause mold and mildew. In virtually all cases, the mold and mildew growth is due to For preventive measures, the WA and CFFA excessive moisture. In order to prevent or elimi- stresses that it is important that any wallcovering nate mold and mildew one must identify and elim- professional (specifier, architect, designer, inate the source of the excessive moisture. In installer or user), homeowner or commercial prop- unusual cases, where moisture or moisture infil- erty owner should conduct ongoing evaluation tration from the wall cavity cannot be eliminated and be aware of any potential construction prob- or sufficiently reduced, use of wallcoverings with lems that may cause excessive moisture. higher permeability ratings should be considered.

This statement serves to communicate the WA The Wallcoverings Association and the Chemical and CFFA’s position regarding the relationship of Fabrics & Film Association’s members agree that mold and mildew to our industry’s products. it is necessary to educate and inform wallcovering It is intended to provide one industry voice and professionals about the prevention and detection to aid in presenting fact and structure in our of mold, proper removal, wall surface treatment response to this growing issue. Additional materi- and product selection, and the proper process for als will serve to support our position statement wallcovering installation. The Wallcoverings and further detail our efforts to provide education- Association and the Chemical Fabrics & Film al and corrective procedures in relation to mold in Association will make every effort to communi- residential and commercial properties. For sim- cate corrective measures and provide educational plicity, all the issues are referred to as mold. tools to guard against mold as it relates to wall- Wallcovering discoloration or wall deterioration covering products.

This position statement is intended to provide one

industry voice and to aid in presenting fact and

structure to the WA and CFFA response to this

growing issue.

3 Introduction

FACT OR FICTION – commercial, institutional and residential buildings RECENT MEDIA HEADLINES and fears of adverse health effects. Seventy-five percent of Americans are concerned that the quality of air in their homes and workplaces could Ridding Hilton of mold may cost have an adverse impact on health, with mold, $20 million dust mites, allergens and particles in the air top- ping their list of concerns.2 Mold plagues school

How household mold gets a grip Are these concerns justified? Who is at most risk for having health problems as a result of mold? A growing problem: Toxic mold is Are all molds toxic? What species of mold are eating away at homes and considered toxic? Where and when does mold homeowners insurers’ profits grow in buildings, what role do wallcoverings play, and why does it seem there is more mold growing Tales of rampant toxic mold get in buildings today as compared with 20 or 30 plenty of attention but science years ago? What can be done to clean up mold, tells a less dramatic story prevent it from coming back and reduce liability in Is your office killing you? case of mold infestation?

Are toxic molds giving you The wallcoverings industry sold more than $940 headaches, asthma — or worse? million of wallcovering products in the U.S. market in 2000, with approximately one-half of the total volume being for commercial buildings.3 With this These recent news headlines reflect increasing large annual customer base, the incidence of interest and concern about how mold affects mold-related complaints has been low, but is still indoor environments and building occupants. of concern as it is rising. Are these media reports based on fact or fiction? In response to this concern, this publication offers Mold as a potentially major building maintenance a review of a variety of scientific, technical, and issue, particularly in hotels and motels in hot and medical resources to answer these questions and humid climates, is nothing new. According to a to educate readers about the complex and often 1990 survey of the hotel and motel industry, mold controversial issues surrounding mold growth in cost American Hotel and Motel Association mem- buildings, particularly with respect to wallcover- bers approximately $68 million each year in lost ings. As noted in the executive summary, the revenues and damage repair. In a follow-up sur- goal is to provide readers with an understanding vey, 70 percent of respondents said that their of the state of the science so they can be better rooms smelled stale, a condition often created or equipped to prevent mold problems, handle mold 1 aggravated by odors emitted by mold. issues when they do occur and practice good risk management. Every effort has been made to A more recent development is the prolific growth equally address both commercial and residential of mold in single-family homes and in other wallcovering products.

4 Section 1. Who, What, Where, When, Why’s of Mold

The first step in answering the questions posed 3. Mold may or may not grow. Whether mold in the Introduction is to realize that mold growth grows and which species may grow depends in homes and buildings and its relationship to on several factors, such as whether the mois- health effects is not as simple as presented in ture dries, lingers or there is repeated water news reports and litigation. It also requires look- damage; the amount of water content or activi- ing at why mold is becoming a more prevalent ty in or on the surface of the building compo- problem, where mold grows and why, and what is nent(s) or material(s) for long enough to sup- it about mold that has prompted so many con- port mold growth; and the nutrition source cerns. “Mold”, “mildew” and “fungi” are used available in or on the component or material’s interchangeably throughout this publication. surface. Some mold species such as They are different names for the same thing. Stachybotrys chartarum, for example, will grow on carpet backings and materials containing 1.1. Mold Growth and Health cellulose, including gypsum wallboard. Other Effects: It’s Not That Simple species such as Penicillium chrysogenum, P. By and large, news reports and litigation tend to exapnsuum or Scopulariopsis sp. grow behind treat problems associated with mold as a three- wallcoverings, whereas Wallemia sp. grows pri- step process: marily on textiles, and Phoma sp., another 1. Water and/or moisture get(s) into or occur(s) common mold found indoors, grows on paint- in a home or building. ed walls. Acremonium sp. and Aspergillus ver- 2. Mold grows. sicolor seem to favor growing on ceramic 3. People get sick. products, paints and wallcovering adhesives. This is an over-simplified approach. The actual Other species that may grow behind wallcover- process is more complicated and has variables ings include Aspergillus niger, Penicillium funi- that are not yet well understood: colosum, Chaetomium globosum, Trichoderma 1. Water and/or moisture get(s) into or occur(s) in sp. and Aureobasidium pullulans. It is also a home or building. possible to have more than one species of 2. Building component(s) and material(s) can be mold growing in the same area. affected to more or lesser degrees. Often the 4. Exposure to mold may cause health effects to term “substrate” is used when referring to the greater or lesser degrees. The state of the sci- surface on which mold can grow. This occurs ence in this area is incomplete, and exposure because in the construction industry, the term standards for molds and mycotoxins as yet do “substrate” means a surface that sits beneath not exist. As a result, the topic of health or underneath a building material. In the wall- effects associated with mold is controversial. coverings industry, however, the term specifi- A byproduct of this controversy is news cally refers to the backing of a wallcovering. reports and litigation that often make assump- To avoid confusion in this publication, the term tions about mold exposure and health effects “substrate” will be used exclusively to describe that are not supported in the medical and sci- the backing of a wallcovering. entific literature.

5 The medical and scientific literature does support In order to grow, mold needs four things: the following positions: 1. A nutrient source. • If mold grows, there is no direct evidence as 2. Appropriate temperature. yet that building occupants will automatically 3. Moisture. be exposed at sufficient levels to cause health 4. Source of mold spores. effects. • Just because mold is visible or there is invisi- A “Mildew Square” developed by James ble mold growth does not mean that allergens, Kimbrough, Ph.D., and Virginia Peart, Ph.D., of the irritants, microbial volatile organic compounds University of Florida, provides an effective illustra- (MVOCs) or other potentially toxigenic compo- tion of these requirements. Stopping mold growth nents, such as mycotoxins that can produce requires eliminating one or more of these essen- adverse health symptoms, are being produced. tial elements. Unfortunately, in a normal comfort- • Some people may develop an adverse health able human environment – homes or commercial, reaction when exposed to mold and some peo- educational or institutional buildings – eliminating ple may not. Also some people may be more spores, warmth and a food source is almost prone to having worse health reactions than impossible. The one element that can be others. removed, however, is moisture.1 • It is quite likely that purported health effects are not attributable to mold exposure or may be attributable only in extreme cases. See Figure 1.1. Mildew Square. Section 1.6, Are Molds Really Toxic?, for more details. Spores

1.2. Overview of Mold in Building and Home Interiors The Essential Homes and buildings are dynamic environments, affected by geographic location; climate; heating, Requirements ventilating and air-conditioning (HVAC) system for Mold design and operation; types of materials used in

construction, finishing and interior design; mois- and Mildew Food ture intrusion; pest colonization; and human activities. Mold and mildew are a form of fungi, which Moisture are ubiquitous – in other words – they are everywhere and exist as a natural part of indoor and outdoor environments. They also are one of the Warmth basic mechanisms of the earth’s ecosystem for recycling plant material.1

6 This section takes a closer look at these elements Typically, antimicrobials are added to these prod- and their relationship to supporting mold growth ucts during the manufacturing process to make throughout a home or building. Section 1.3, them resistant to mold growth. Wallcoverings and Mold: A Function of Moisture Levels and Permeability, focuses specifically on Also important is keeping the area and building why mold potentially grows on or behind wallcov- and finishing materials such as wallcoverings erings, and Section 1.4, Mold, Mildew, Fungi – clean during and after installation as dirt, dust and What’s the Difference?, concentrates on sources other organic materials can become trapped of mold spores. Section 4.1, Eliminate Sources of behind the wallcovering and/or in the wall cavity Moisture, discusses in detail how to control and provide a food source for mold. See Section and/or eliminate moisture sources. 4.4, Good Practices – Keep Materials and Work Area Clean, for more details. NUTRIENT SOURCES. There are numerous sources in today’s homes and buildings to satisfy TEMPERATURE. Homes and buildings are typi- the nutritional needs of mold, including materials cally maintained at a temperature of 65 degrees F containing cellulose, such as found in some wall- to 75 degrees F (18 degrees C to 24 degrees C), coverings, gypsum wallboard, paint, wood panel- which is hospitable to many species of mold, ing, plywood, oriented strand board (OSB), pre- some of which can survive at temperatures below cast panels and ceiling tiles, fabrics, carpets, 50 degrees F (10 degrees C) or above 122 upholstered furniture, fiberglass-lined air ducts, degrees F (50 degrees C). At relatively low tem- and other porous materials where fungi break peratures (50 degrees F to 60 degrees F), spores down the material itself or use organic debris that take longer to germinate and growth is slower. has collected. While wallcoverings and adhesives/primers contain biocides (also called MOISTURE. For mold to grow in homes and mildewcides), some adhesives may also contain buildings requires sufficient moisture for a long starch, which may provide a potential food source enough period of time to support growth. There for mold. are primarily four factors that influence the amount of moisture available for mold growth: Some traditional construction and finishing mate- 1. Building tightness, which does not allow mois- rials contain natural chemicals that retard biode- ture to escape to the outside or to be removed terioration; for example, the heartwood of some from the inside air through dehumidification. tree species contains terpenes and other sub- 2. Liquid water infiltration from the outside as a stances that inhibit fungal growth. Man-made result of a leaky building envelope or structural products such as ceiling tiles, wallcoverings, fab- failure. rics, carpets, draperies, upholstered furniture, 3. Moisture condensation on or near mold-sus- fiberglass insulation, gypsum wallboard covered ceptible building materials or components, in paper with cellulose, and pressed wood prod- which originates from water vapor inside or ucts with added binders and resins are suscepti- outside the home or building. ble to mold growth as they lack natural antimicro- 4. Moisture generation within the home or building bial compounds and provide a nutrient source.4 by the occupant and the occupant’s activities.

7 The following is a more detailed discussion of products for building furnishings, finishings, wall- these factors and why they contribute to high coverings, flooring and cleaning.5 moisture levels in buildings. WATER INFILTRATION. Any opening in the build- BUILDING TIGHTNESS. By and large, homes ing envelope (whether a residential or other type and buildings are built much tighter than their of structure) may permit liquid water and water counterparts in the first half of the 20th century. vapor to penetrate the home or building and A typical home and building today is almost twice accumulate on mold-susceptible materials or as tight as those built a few decades ago. This components. These sources include: increase in tightness can be attributed to an intro- • Leaky windows and door openings. duction of new materials and production tech- • Roof leaks. niques, thermal insulation and elimination of • Missing, inadequate or poorly designed flashing. active chimneys in residential construction, and • Lack of gutters. the advent of mechanical HVAC systems.5 In • Foundation leaks. response to the energy crises in the 1970s, tight- • Plumbing leaks. ening up homes and buildings to save energy • Tuckpointing, particularly where the cement became the mantra of all commercial, institutional between bricks has worn thin. and residential building construction. • A myriad of other causes.

Efforts to save energy have been successful. For Surprisingly large quantities of water can pass example, even though the number of commercial through very small cracks/openings if they are buildings and the amount of commercial floor located at critical junctures in the drainage path space has increased since 1979, total energy con- of the envelope. Liquid water also can travel sumption has remained flat.6 One significant along beams and piping and show up as a leak in unanticipated byproduct of these efforts, however, another part of the home or building. Since such is increased moisture levels, in terms of relative junctures typically occur at the base of window humidity in interior spaces and moisture content openings and where roofs intersect walls, gener- and water activity in building materials. ally tiny cracks develop exactly where they can do the most harm. This is why seemingly minor details with missing or poorly designed flashing In addition, the amount of air exchanged between can have such a pronounced impact. conditioned indoor (HVAC) spaces and the outdoors diminished as buildings became tighter, Moisture also can enter the building envelope resulting in significantly less dilution of moisture through capillary action; that is, a natural wicking and indoor pollutants, such as formaldehyde, force that will draw water from one source into volatile organic compounds (VOCs) and carbon the building envelope cavity. This primarily dioxide. This trend occurred concurrently with occurs at the base of exterior walls.7 Capillary the introduction of metal and plastic window action also can occur when building components frames, glass wall systems that do not permit nat- that transmit water are exposed to drenching con- ural ventilation, and new synthetic materials and ditions, such as excessive rainfall.

8 The fundamental principle of rain and ground In addition, thicker insulation in the exterior wall water control is to shed water by layering materi- cavities creates lower drying potentials for als in such a way that water is directed downward materials making up the wall structure.5 out of or away from the structure. In short, drainage is the key. Drainage applies to every- The urea formaldehyde foam insulation used in thing – building foundation, walls, roofs, doors, Canadian homes until the early 1980s provides a windows, skylights, balconies, decks, railings and useful example of how new construction materials dormers to name a few.8 Regardless of the can contribute to creating suitable conditions for cause, entry of liquid water into any building mold growth. Extensive growth of Penicillium sp., structure must be prevented See Section 4.1, Trichoderma harzianum and Paecilomyces variotii Eliminate Sources of Moisture, for more information. were frequently found in external walls of affected homes.9 In addition to condensation and leakage In addition, water and moisture present in building problems, moisture responsible for the mold growth materials or at the construction site can provide may have originated from water released in the wall ideal conditions for mold growth once the materi- cavity during the curing of the foam insulation.4 als are installed; for example, oriented strand board (OSB) and other press-wood products, ceil- Condensation occurs when warm air, which holds ing tiles and gypsum wallboard that are allowed higher amounts of moisture than cold air, travels to get wet from rain and/or other sources.7 through a wall to the colder side. As the warm air Improper storage of building materials also can begins to cool, it is forced to release moisture. result in the materials getting and staying wet This is referred to as the dew point. When there is while waiting installation. a significant temperature drop across the wall cavity, the dew point will occur somewhere within Water also may enter a structure through porous that cavity. materials such as wood and concrete or as a result of leakage and structural faults. Inadequate In cold climates, moisture can collect in and on drainage around the foundation also allows con- internal surfaces of exterior walls. When the inter- siderable moisture to enter a basement.4 nal surface of these walls becomes too cold, the surface relative humidity may exceed 65 percent or WATER CONDENSATION: A MATTER OF DEW condensation may occur when the temperature at POINTS, HUMIDITY. Mechanical HVAC systems the inner surface of the external wall is at or below became popular in the mid-1960s and really the dew point temperature of the room air. Both gained momentum in the 1970s. In a cooling (hot instances provide a ripe environment for mold and humid) climate, as the building envelope growth. Hidden mold growth also can occur at the becomes tighter, any depressurization of condi- first condensing surface, which may be the OSB or tioned spaces (the indoor environment is at a plywood on the internal surfaces of the external negative pressures as compared with the outdoor sheeting. Internal humidity sources in pressurized environment) may increase infiltration of water homes and buildings, envelope vapor barriers vapor from the outside. Similarly, in a heating placed on the cold side of insulation or placed on (mixed or cold) climate a pressurized building can both the warm or cold side of insulation, and base- cause warm moisture-laden air from inside the ments insulated on the inside all can contribute to building to exfiltrate into wall and roof cavities. envelope moisture problems.4

9 In warm climates, air conditioning plays a key • Wind effect from the pressure of wind and varies role. The accumulation of moisture on or in the with wind direction.1 building envelope is strongly influenced by indoor temperature, outdoor humidity and building pres- Water requirements for mold vary over a broad surization. Mold growth typically occurs on inter- range, and in the scientific and technical literature nal surfaces of external walls, because the sur- they are usually referred to in terms of the water faces are cooled by air conditioning to below or activity (aw) at which the fungi can grow. Harriett near the dew point of the humid air infiltrating into A. Burge, Ph.D., a recognized expert in mycology, the envelope. defines water activity as “the equilibrium relative humidity in the immediate vicinity of the substrate [building] material [or building component] and is Moisture also can enter a building as a result of expressed as a decimal. For example, animal air leakage, such as through or around windows cells require aw near 0.99 or 1.00, which is essen- or roof flashing, movement of humid air into the tially saturation.”10 In other words, water activity interior through cracks or loose construction of is a measure of a building material’s ability to con- the building envelope, and diffusion of water tain water to support mold growth at its surface vapor from the outside toward the cooler interior. and not the ambient relative humidity in the room. In structures with either crawl space or attic, air The ambient relative humidity expresses an aver- leakage in the HVAC duct system into these areas age of these various levels. This is not necessari- may cause a negative pressure in the occupied ly representative of the relative humidity at a areas. Any air that has leaked from the duct sys- building material’s surface.11 Rooms can have tem would have to be made up from outside air. hot and cold spaces and thus different relative As noted, the diffusion or infiltration of air is humidity levels. What this means is surface con- caused by the home or building’s interior being at densation is not always necessary for mold a negative pressure with respect to the outdoor growth to occur.12 environment.1,4 High amounts of air infiltration, Some fungi can grow and reproduce at a as low which can bring in high amounts of moisture, w as 0.69, although optimal growth probably occurs can result in mold growth on all interior walls. at somewhat higher levels. Many fungi have an optimal a of 0.80 to 0.90, which means that if The Hospitality Lodging & Travel Research w the humidity at a surface reaches 80 percent, pro- Foundation’s landmark report on mold and mildew viding the building material contains the appropri- in hotel and motel guestrooms in hot and humid ate nutrients and no inhibitors, some fungi will be climates cited three primary causes for water able to grow and possibly reproduce. Humidity vapor infiltration due to negative pressure in many levels at the surface of the building material must hotel and motel properties: be maintained long enough for fungi to become established, usually about 48 hours. For example, • Fan effect from air being exhausted from bathroom if 80 percent relative humidity is present more fans without sufficient make-up air being added. than half the time, mold risk increases rapidly. • Stack effect from the pressure of warm air rising in The more water that is available, the more fungi a building. there are that can colonize a surface.4, 11, 12

10 MOISTURE GENERATION. As noted, building ings, an effective line of defense is to first and occupants and their activities are a significant foremost eliminate the source(s) of moisture and source of moisture in home and building interiors. air infiltration, and second is to ensure that water Activities that can add moisture include operating vapor in the wall cavity can escape to the build- showers without bathroom ventilation to the exte- ing’s interior through the wall surface. In new rior, cooking without ventilation of steam to the homes and buildings, the key is to design and exterior and drying clothes without venting the build the structure to prevent favorable conditions unit to the exterior, or using kerosene heaters or for mold growth in the first place. In both cases, ventless gas appliances. Ventless gas appliances choosing the right wallcovering in terms of its are a significant source of indoor moisture. They permeability is vital. See Appendix C, NIST add 1 oz. of moisture for every 1,000 BTU rating Personal Computer Model (MOIST) for information per hour. For example, unvented gas stoves or on a computer model developed by the National ovens can generate 8 oz. to 75 oz. (one cup to Institute of Standards and Technology (NIST) for more than one-half gallon) of moisture per hour.13 evaluating moisture content of different building In hotel and motel rooms in hot and humid cli- materials in different settings as a function of mates, up to 28% of interior moisture can come time. from building occupants and their activities.14 Figure 1.2 illustrates the relationship of moisture SPORES. As discussed, mold is found every- level, room temperature and wallcovering perme- where in the indoor and outdoor environment. ability along with the level of associated risk for Section 1.4, Mold, Mildew, Fungi – What’s The mold growth. For example, if a home or building Difference?, provides a comprehensive discussion has a high level of moisture intrusion into the wall on how mold grows and the various sources of cavity and an impermeable wallcovering is used, mold spores in indoor environments. the risk for mold growth is very high as was the case for the buildings cited in The Hospitality 1.3. Wallcoverings and Mold: Lodging & Travel Research Foundation’s report on A Function of Moisture Levels mold in hotel and motel guestrooms in hot and humid climates.11 On the other hand, if there is a and Permeability low level of moisture intrusion into the wall cavity As noted in the previous section, warm humid air and a permeable wallcovering is used, then the infiltrating into a wall cavity condenses when the risk for mold growth is very low. Selecting a per- dew point is reached inside the wall cavity as a meable wallcovering can lower the risk for mold result of the warm moist air coming into contact growth in a building with a high level of moisture with the cool temperature of the wall surface. and low indoor room temperature from air condi- When this condition prevails, the backside of the tioning. See also Sections 4.1, Eliminate Sources wallcoverings and the wallboard to which the of Moisture; Section 4.2, Select Materials and wallcovering is attached become an ideal place Finishes to Prevent Mold; and Section 4.3, Build It for mold growth.1, 4 In existing homes and build- Right in the First Place, for more details.

11 Figure 1.2. Risk of Mold Growth as a Function Description of Wallcoverings, for more detailed of Moisture Level in the Wall Cavity, Room descriptions of wallcoverings products and federal Temperature and Wallcovering Permeability – specifications for wallcovering physical properties. Cooling Climate* DECORATIVE LAYER. In Level of Risk Impermeable Semi-permeable Permeable most cases, this layer is the Wallcoverings Wallcoverings Wallcoverings thinnest and consists of the inks applied to the top of the Higher Risk High Level of Moisture; intermediate layer. The deco- Low Room Temperature rative layer provides the design and color and is usual- Medium Level of Moisture; Overall Effect ly the major reason a wallcov- Medium Room Temperature ering is chosen. The design is printed using various methods Low Level of Moisture; such as gravure, flexography, High Room Temperature Lower Risk surface and screen. Also, tex- turing of the surface may * See Figure 4.1, in Section 4.1, Eliminate Sources of increase the wallcovering’s permeability. This Moisture, for a map of areas in the U.S. that layer may also have a protective polymer coating the U.S. Department of Housing and Urban Development to provide added performance characteristics. has designated as a cooling climate. For residential wallcoverings, the decorative layer may be thicker than the balance of the wallcovering’s construction for some special products, The previous section provided an overview of how such as expanded patterned PVC, paintables and moisture can enter a building and become high gravure. This thicker decorative layer typical- trapped in the wall cavity and condenses. The ly does not interfere with permeability because following discussion looks at the other essential the designs are discrete areas and do not fully factor in this equation: the permeability of wallcover the surface. coverings. In short, how permeable a particular type of wallcovering is depends on its composi- INTERMEDIATE LAYER. This layer, also called tion and the porosity of the materials used in its the ground, provides the surface on which the construction. decorative layer is printed. It also provides the background color, which is often white but can WALLCOVERINGS CONSTRUCTION. The majority be any color depending on the design. The inter- of wallcoverings have three layers, which can be mediate layer can range in thickness from less made of a variety of materials depending on the than 1 mil to as much as 20 mils as in the heavier design and desired effect. See Appendix B, solid vinyl products.

12 SUBSTRATE OR BACKING. This is the layer MATERIALS. Vinyl is used in many types of com- that is adhered to the wall. The substrate, which mercial and residential wallcoverings, because it is important in determining which wallcovering is more durable, stronger and easier to clean than product will be used in a particular application, other wallcovering materials such as papers, can be made of a wide variety of materials, linens, foils or grass cloth. While vinyl is the most including: widely used material for commercial and residen- • Paper backings, which are used on paper- tial wallcoverings, other natural and synthetic backed vinyls, vinyl-coated papers and spe- materials are used to achieve a particular appear- cialty products. Strippable residential paper ance, texture or performance characteristic. backings, which offer wet strength to allow These materials include strippable paper, string activation of prepaste by immersing the prod- effects, natural and synthetic textiles, polyester uct in water, are wood-free bleached cellulose and olefin, cork and cork veneer and wood pulp that is saturated with acrylic latex and veneer. See Appendix B, Description of then groundcoated on the print surface for Wallcoverings, for details about the materials improved print and scrubbability. used in wallcoverings. • Coated woven fabric backings, which are commonly referred to as scrim or osnaburg. Scrim PERMEABILITY RATINGS. Building materials can is used primarily in light construction and be separated into three general classes depend- osnaburg in medium to heavy usage areas ing on their permeability as shown in Table 1.1. such as commercial building corridors. While there are no standard industry permeability • Coated non-woven fabric backings, which ratings for wallcoverings, Table 1.1 also shows often improve wallcovering-printing techniques results from internal vapor transmission testing compared with woven fabrics while maintaining conducted by a major wallcovering manufacturer, physical strength qualities necessary for com- which is suggestive of what these ratings might mercial installations. be. These values, along with the following dis- • Latex acrylic backings, which are used on tex- cussion, offer a helpful comparison with other tile-faced wallcoverings to make them more building materials. stable and improve hanging qualities.15

The substrate or backing also may provide a food The substrate, which is source for mold as paper contains cellulose and woven fabrics may trap dust, allergens and important in determining organic materials in their weaves. In addition, which wallcovering product pre-mixed adhesives used to adhere the wallcovering to the wall may contain starch, which is a will be used in a particular nutritional source for mold. For this reason, these adhesives contain a mildewcide to prevent mold application, can be made of growth on the backside of wallcoverings. See a wide variety of materials. Section 4.2, Select Materials and Finishes to Prevent Mold, for more details.

13 As there are several recognized test methods for The permeability of a particular type of wallcover- water vapor transmission, disclosing which ing varies depending on the weight and porosity method was used when discussing permeability of the materials used. For example, a Type I vinyl of wallcoverings and building materials is impor- wallcovering weighing 12 oz to 19 oz may have a tant to avoid confusion about the testing results. perm rating of 1 (semi-permeable), whereas a The values in Table 1.1 were derived using ASTM Type II vinyl wallcovering weighing 20 oz and E96-95, Standard Test Methods for Water Vapor higher has a perm rating of less than 1 (imperme- Transmission of Materials, wet cup method at 73.4 able). Some manufacturers have introduced degrees F (23 degrees C) and 50 percent relative “microvented” wallcoverings that feature approxi- humidity outside the dish. mately 135 very tiny holes per square inch in the vinyl wallcovering. These holes allow water vapor It is important to note that other test methods to escape. Even though most wallcoverings can are commonly used. Also of note is a U.S. be “microvented,” care should be taken, as Department of Housing and Urban Development “microventing” is not recommended for vinyl- (HUD) standard for manufactured housing that coated paper, paper backed vinyl wallcoverings or has proposed a waiver on permeability for the vinyl wallcoverings with a non-woven substrate. wall composite from 1 to 5 perms to achieve mold “Microvented” wallcoverings have a permeability resistant exterior wall construction in all climates rating of between 8 and 12, which qualifies them without the use of vapor barriers. The values in as permeable.17, 18 the HUD proposed waiver were derived using the dry cup method.16

As there are several recognized test

methods for water vapor transmission,

disclosing which method was used when

discussing permeability of wallcoverings

and building materials is important to

avoid confusion about test results.

14 Table 1.1. Building Materials, Wallcoverings Permeability

General Classes19 Wallcoverings

Classification Building Materials Type Estimated Perm Rating

Vapor impermeable – Rubber membranes, Type II vinyl Less than 1* referred to as vapor polyethylene film, glass, Mylar or Foil, barriers aluminum foil, sheet PET laminated to metal, oil-based paints Non-woven and foil-faced insulating sheathings

Vapor semi-permeable Plywood, OSB, unfaced Untextured vinyl 1 - 3 – referred to as vapor expanded polystyrene retarders (EPS), fiberfaced isocya- Textured vinyl 2 - 10 nurate, heavy asphalt impregnated building PVC Liquid- coated 2 - 15 papers, some latex non-woven paints and bitumen fac- ing on most fiberglass batt insulation

Vapor permeable – Unpainted gypsum “Microvented” vinyl 8 - 2* referred to as board and plaster, wallcovering breathable unfaced fiberglass insulation, cellulose insula- Non-woven 4 - 100* tion, unpainted stucco, (Composition variation) lightweight asphalt impregnated building Woven fiberglass ~10 or higher papers, asphalt impregnated fiberboard, exteri- Paintable paper 8 - 20* or gypsum sheathings, Residential cement sheathings, and Simplex & Duplex “housewraps” wallpaper (non-vinyl coated)

Prepasted paper 2 -30

Saturated paper 2 -30** Strippable Paper

Textiles ~10 - 100

Paintable residential 10 or higher*** paper

Natural products 15 - ~100

* Testing conducted in accordance with CFFA 19 Procedure B (ASTM E96-95, Standard Test Methods for Water Vapor Transmission of Materials, wet cup method at 73.4 degrees F (23 degrees C) and 50 percent relative humidity outside the dish). Other methods can be used. ** Prepasted wallcovering should be tested with prepaste removed or not added to the paper. Various constructions of wallcoverings will give a wide variation in perm values. *** The type of paint and number of coats of paint can cause significant variation in perm values. 15 Typically, non-woven wallcoverings are made of would tend to make the wallcovering less porous. polyester and wood cellulose, which allows for Paper or non-woven wallcoverings may have fill- transmission of moisture. Perm ratings for non- ing agents, which are used to get better quality of woven wallcoverings may range as low as 4 to as print and to create a more even appearance. high as 100. This wide range depends on how Coatings made from clays and calcium carbon- tightly the wallcovering is compressed. Plain ates are used to achieve printing performance wallcovering papers, on the other hand, are less characteristics similar to vinyl. Acrylic and other porous and may have a perm rating of about 8 to emulsion polymers can be formulated to make a 20. Saturated paper is comprised of a latex wallcovering coating that is porous. The effect is binder that holds wood-free pulp of cellulose and similar to “microvented” wallcoverings. Wall-cov- polyester fibers together, which gives the wallcoverings with this type of coating have the advan- ering strength. The advantage is it can look like a tage of being more permeable but are less vinyl wallcovering, but unlike vinyl wallcoverings it durable than vinyl. has a higher perm rating of 2 to 30. Added treat- ments to the decorative layer tend to make this 1.4. Mold, Mildew, Fungi – type of wallcovering less permeable. What’s The Difference? Textiles also known as woven wallcoverings typical- Fungi are naturally occurring organisms that ly are made from synthetic fibers such as poly- make up approximately 25 percent of the earth’s propylene (generic term is polyolefin). Because biomass and play an essential role in the process- there is more space between the fibers, this type of ing of decaying organic matter into substances wallcovering would likely have a relatively high perm that are necessary for sustaining plant and animal rating of about 10 to 100 or higher. life.20 Mold and mildew are generic terms that are used to describe essentially the same fungi, with Woven fiberglass wallcoverings are made of fiber- mold used to describe fungi growing on surfaces glass that appears to be woven. Usually, this type and mildew to describe fungi growing on fabrics. of wallcovering is white and, once applied to wall, is painted. The perm rating varies depending on type of paint used and number of coatings applied to the Although mentioned earlier in this publication, it surface; for example, enamels or epoxy coatings. bears repeating that mold is found everywhere in In general, the rating is 10 or higher. both indoor and outdoor environments. And as described in Section 1.2, Overview of Mold in Natural products, such as grass cloth, are not often Building and Home Interiors, in order for mold to used in commercial applications in the US as they grow it needs a nutrient source, appropriate tem- lack the durability and strength needed to withstand perature, moisture and a source of mold spores. day-to-day abuse. Because they have a very loose To keep mold from growing indoors requires elimi- composition, these products have very high perm nating one of these four elements, which is not ratings. In general, the rating is 15 to 100. easily done. The key is moisture. By eliminating moisture, mold growth can be prevented. See Permeability also depends on whether a protec- Section 4.1, Eliminate Sources of Moisture, for tive coating is applied to the design layer, which more information.

16 Not all species of mold are destructive to building Fungal spores germinate to produce hyphae, materials or may cause adverse health effects. A which grow and branch within or on the building number of varieties are essential to every day life materials or components, typically producing a and are beneficial to health. Fungi, for example, colony that eventually forms a new generation of can be commonly found on grocery store shelves, spores.25 Fungi also can spread if a fragment of such as button mushrooms or more exotic vari- broken hyphae is transplanted to an area with eties for the gourmets at heart. Fungi are used in adequate warmth, moisture and nutrient source.15 the making of common foods; for example, relat- Spores contain one to many cells and differ great- ed species and strains of Saccharomyces cere- ly in size, shape, color and method of formation; visiae (yeast) are commonly used in baking and however, they are always microscopic, ranging for some types of fermentation, including alco- from fewer than 2 micrometers to more than 100 holic beverages. Yeast also is often taken as a micrometers. Under adverse environment condi- vitamin supplement because it is 50 percent pro- tions, some fungi are able to form chlamy- tein and is a rich source of B vitamins, niacin and dospores, which are thick-walled dormant spores folic acid.21 Different strains of Penicillium are that develop from transformed vegetative used in making Stilton, Buxton and blue cheese hyphae.25 Fungi spores also can survive for many to name a few.22 years in dry or hot environments, requiring only moisture and available organic matter in order to In addition, fungi are a valuable resource for com- germinate.26 monly used medicines; for example, cyclosporine, an important immune suppressant drug used with Fungi are resilient and adaptable and can colo- organ transplant surgery, is made from the fungus nize dead and decaying matter, such as textiles, Tylipocladium inflatum. Isopenicillin N. is the fun- leather, wood and paper, and even damp inorgan- gus from which penicillin antibiotics are derived. ic matter, such as glass, painted surfaces, metal In fact, fungi are the second largest microbial and bare concrete, if organic nutrients, such as producers of antibiotics behind a specific type dust and soil particles, are present. Some fungi of bacteria.23 can germinate in as little as 4 to 12 hours, and, if left undisturbed, fungi can grow and spread in 24 Unlike bacteria and algae, fungi cells are eukary- to 72 hours.20, 26 otes; that is, they have a nuclear envelope.24 The majority of species, including those most abundant in the environment are saprobes, which obtain nutrients from nonliving organic matter. Not all species of Structurally, fungi exist as single cells such as mold are destructive yeast, or far more commonly, as threadlike hyphae. The collective mass of interwoven to building materials hyphal filaments is referred to as mycelium. or may cause adverse While individual hyphae are microscopic, the mycelium is often visible to the naked eye.25 health effects.

17 1.5. Different Types Phoma sp. is common mold found indoors. It is of Indoor Molds similar to the early stages of growth of Chae- tomium sp., and produces pink and purple spots Approximately 69,000 species of fungi have been on painted walls. It also will grow on butter, described in the scientific literature and estimates cement and rubber. Rhodotorula sp. is a reddish for the total number exceed 1.5 million.25 Fungi yeast typically found in moist environments such are divided into groups based on spore shape as cooling coils and drain pans. In some coun- and method of formation. Only members of three tries, Rhodotorula sp. is the most common yeast of these groups commonly grow on building genus in indoor air. materials, including wallcoverings. Zygomycetes are relatively common in building and house dust, Stachybotrys atra, Stachybotrys alternans and and require relatively simple carbon sources and Stachybotrys chartarum are considered to be the very wet conditions. Basidiomycetes include all same organism. Stachybotrys is a slow-growing mushrooms and shelf fungi, including those that fungus and does not compete well with other degrade wood products, and a few yeasts found rapidly growing fungi. This dark colored fungus in buildings. By far, the largest of the groups that grows on building materials with high cellulose con- can colonize building materials are Ascomycetes. tent and low nitrogen content and areas with What is typically known as mold and mildew fall a relative humidity above 55 percent. Until very within this group.10 recently, researchers believed that Stachybotrys was rarely found in outdoor air samples, and was usually The University of Minnesota Department of difficult to find in indoor air samples unless it is Environmental Health and Safety’s website fea- physically disturbed or there is a drop in the relative tures a fungal glossary on its indoor fungal humidity. The spores are in a gelatinous mass and resources page, including species-specific infor- will die readily after release, but the dead spores can mation derived from an extensive review of avail- still be allergenic and toxigenic. able scientific literature. The following discussion Aureobasidium pullulans is one of several genera of Cladosporium sp, Phoma sp., Rhodotorula sp. of “black yeasts”, characterized by mostly slow- and Stachybotris is from that glossary.27 growing, black, pasty colonies. This yeast-like fungus is commonly found on caulk or damp Cladosporium sp. is the most commonly identified window frames in bathrooms. outdoor fungus. The outdoor numbers are lower in A more recent study of indoor/outdoor mold the winter and often higher in summer. It is also ratios across the US, however, identified found often indoors but in lower levels than out- Stachybotrys chartarum in 6 percent of indoor doors. Indoor Cladosporium sp. may be different air and 1 percent of outdoor air of the buildings from the species identified outdoors. A wide num- studied. These researchers concluded that ber of organisms have been placed in the Stachybotrys is a normal component of airborne Pencillium genera. Identification to the species fungi and detection of this mold species is not as level is difficult. It is often found in aerosol sam- rare as was previously thought.28 ples, soil, food, cellulose, grains, paint and compost piles. It also is commonly found in carpet, Table 1.2 lists some of the common molds and wallpaper and in interior fiberglass duct insulation. locations found in indoor environments.20, 27

18 1.6. Are Molds Really Toxic? there is little scientific or medical evidence that Although much as been made in news reports and demonstrates that some molds are indeed toxic. in recent litigation about health effects from expo- But at the same time there is consensus that some sure to mold, especially with regard to Stachybotrys species of fungi can produce mycotoxins, which are chartarum, this topic is somewhat controversial as considered to be toxic to humans and animals.

Table 1.2. Common Indoor Molds

Fungal Species Indoor Materials

Alternaria alternata Window sills, walls, carpets, textiles

Aspergillus versicolor Wood, wallcovering adhesives

Aspergillus fumigatus House dust, potting soil

Aspergillus fumigatus Textiles, soil, fruit, grains, vegetables Paper, materials containing cellulose, Chaetomium sp plant compost, drywall paper Window sills, wood, textiles, fiberglass Cladosporium herbarum duct liners Cladosporium sphaerospermum Paint, textiles, plants, food, soil

Epicoccum sp. Plants, soil, textiles, paper products

Fusarium sp. Soil, humidifiers

Geotrichum sp Paper, soil, water

Paecilomyces sp. Soil, dust, less frequently in air

Papulospora sp. Soil, textiles, paper

Penicillium sp. Wallpaper, behind paint Wallpapers covered with Paris green, Scopulariopsis sp. house dust Stachybotrys chartarum (aka Stachybotris atra, Stachybotrys alternans) Carpet, materials containing cellulose Other fungi, materials containing cellulose, Trichoderma sp. unglazed ceramics Dead plants, materials containing Ulocladium sp. cellulose, textiles Wallemia sp. Textiles

19 Specifically, data are lacking to support threshold In addition, whether or not symptoms develop limit or dose-response relationship for exposure. depends on the nature of the species involved, As of this writing, the Occupational Safety and the metabolic products being produced by the Health Administration (OSHA), the National species, the amount and duration of exposure Institute for Occupational Safety and Health and the specific susceptibility of those exposed. (NIOSH) and the American Conference of It also depends on whether the spores, hyphae Governmental Industrial Hygienists (ACGIH) fragments and metabolites such as MVOCs are have not established permissible exposure limits released into the air and inhaled, physically con- (PELs), recommended exposure limits (RELs) tacted (dermal exposure) or ingested.31 or threshold limit values (TLVs) for bioaerosols associated with mold. VOLATILE ORGANIC COMPOUNDS. Volatile organic compounds, also called microbial volatile organic compounds (MVOCs), are responsible for Systemic infections, which are also caused by the musty odors characteristic of mold growth. In mold, are not common, although opportunistic the process of degrading building materials and fungal pathogens, such as Aspergillus sp., are components as nutrients, fungi produce many common in indoor air. Those at most risk for metabolic products, primarily carbon dioxide and these infections include people who have severely water. Under some circumstances, most fungi compromised immune systems, such as those can also produce ethanol and ergosterol, which undergoing chemotherapy, people with HIV/AIDS are useful compounds for determining if there is or those who have had organ or bone marrow active mold growth, and a variety of volatile and transplants.20, 30 A rare, but much more serious non-volatile organic compounds.32 Exposure to immune-related condition, hypersensitivity pneu- high levels of VOCs, from any source – not just monitis, may follow exposure (usually occupation- mold – can irritate mucous membranes and cause al) to very high concentrations of fungal and other headaches, attention deficiencies, inability to con- microbial proteins.29 centrate and dizziness.20

In its position statement on Opinions differ, however, adverse human health effects whether exposure to these associated with molds in the mycotoxins produces indoor environment, the American disease. Harriet A. Burge, College of Occupational and Ph.D., a recognized expert Environmental Medicine reaffirms in mycology, said that such that “current scientific evidence reports “are anecdotal and does not support the proposition lacking sufficient data to that human health has been document a clear connection adversely affected by inhaled between exposure and mycotoxins in home, school or disease.”10 office environments.”29

20 ALLERGENS. Allergic reactions are the most mode of human exposure to mycotoxins is inhalation common response to molds. People who are of spores and mold-contaminated materials. Molds atopic; that is, who are genetically capable of that are important potential producers of mycotoxins producing an allergic response, may develop indoors include certain species of Fusarium, symptoms when their respiratory system or skin Penicillium, Aspergillus versicolor and Stachybotrys is exposed to mold or mold byproducts to which chartarum. There is a great deal of information they have become sensitized. Sensitization can about the effects of ingesting certain mycotoxins in occur in atopic individuals with sufficient expo- humans and animals, but investigators have only sure. Researchers estimate that 10 percent of just begun to study health implications of inhaling the population has allergic antibodies to fungal these substances.20 antigens and only one-half of these 10 percent, or 5 percent, are expected to show clinical illness. Among the health effects attributed to mycotoxins Symptoms can range from mild to transitory are mucous membrane irritations, including eye, responses such as watery eyes, runny nose, nose and throat, from exposures at high levels.20, 33 throat irritation, coughing and sneezing to chronic When mycotoxins or particles carrying mycotox- illnesses such as sinusitis and asthma. An impor- ins are inhaled, they may reach the lung alveoli tant note is that indoor mold allergens probably and induce an inflammatory reaction, creating affect fewer people than do allergens from cats, toxic pneumonitis. Severe toxic pneumonitis mites and cockroaches or outdoor molds. Also can cause fever, flu-like symptoms and fatigue. of note is a significant proportion of people with Inhaling large concentrations of dust with mold asthma (10 percent to 32 percent) are sensitive spores may cause hypersensitivity pneumonitis. to mold.20, 29 This condition is generally an occupational hazard in agriculture, but has been reported in individuals MYCOTOXINS. A wide variety of molds can pro- in residences.20, 30 Other symptoms attributed to duce mycotoxins, and some of these compounds mold mycotoxins include headache, dizziness, are toxic to humans and animals.24 While some dermatitis, diarrhea and impaired or altered mycotoxins are associated with hyphae, the primary immune function.34

Allergic reactions are the most

common responses to mold.

Indoor mold allergies probably

affect fewer people than do

allergies from cats, mites and

cockroaches or outdoor molds.

21 Researchers do not yet fully understand the specific MOLD AND SICK BUILDING SYNDROME. conditions needed for mycotoxin production, but Although not attributed exclusively to mold, sick studies are under way. The U.S. Environmental building syndrome is ascribed to inadequate ven- Protection Agency (EPA), for example, is presently tilation, chemical contaminants from indoor and conducting research on Stachybotrys chartarum to outdoor sources, and biological contaminants determine “the environmental conditions required for such as molds, bacteria, pollens and viruses. A sporulation, emission, aerosolization, dissemination 1998 survey on indoor air quality, ventilation and and transport of [Stachybotrys] into the air.”35 A health symptoms in schools by Lawrence complicating factor to determining these conditions Berkeley National Laboratory revealed that micro- is a single species of mold may produce several dif- biological pollutants, along with VOCs, carbon ferent mycotoxins, while different mold species may monoxide and carbon dioxide, were some of the produce the same mycotoxin.36, 37 Mycotoxin pro- most commonly measured air pollutants in duction for a given species is highly dependent on schools. The survey cites water damage leading growth conditions, such as nutrient availability, tem- to mold contamination as the second most fre- perature and humidity. Ronald E. Gotts, M.D., Ph.D, quently reported building-related problem, with states, “Just because a toxigenic mold is found in an the root cause of many of the problems being indoor environment, it does not necessarily mean inadequate and/or deferred maintenance of that the mold is producing mycotoxins.”38 school buildings and HVAC systems.39

“Just because a toxigenic mold is

found in an indoor environment, it

does not necessarily mean that the

mold is producing mycotoxins,”

said Ronald E. Gotts, M.D., Ph.D.

22 Section 2. How to Tell if a Mold Problem Exists

The presence of mold, water damage or musty very high, the cost of hiring a less competent odors in a building should be addressed immedi- firm usually turns out to be higher, with more ately. Assessing complaints about mold infesta- testing costs, more remediation costs and tion in buildings is critical to not only confirming more legal entanglements being the likely out- that a problem exists, but also to identifying the come. Here are some questions to ask, fol- source of the problem, what type of mold is pres- lowed by tips about what to look for in the ent, recommending a remediation plan and devel- answers: oping a strategy to prevent the problem from • Find out how long a firm has been doing indoor recurring. Only specially trained personnel who air quality–related work. understand how buildings work and how to • Review the credentials of the team and sup- find sources of moisture should assess mold porting experts available through the firm. problems and recommend a remediation plan. • Ask the prospective expert: For these reasons, the wisest course of action is √ How many mold-related jobs has your firm to call an expert! done and when was the first one? Look for experience prior to 1997. 2.1. Finding a Qualified Expert √ How many and what kind of samples do you typically take on your first inspection? LET THE BUYER BEWARE. Finding a qualified As a starting point, good firms rely on visible expert is a challenging problem as there are relative- inspections and use surface and source ly few real experts in the field of assessing, remedi- sampling only to identify visible molds. ating and controlling mold in buildings. In response √ What certifications does your firm bring? to news reports and litigation, many firms, staffed Certifications such as a professional engi- with former asbestos experts, have suddenly neer (PE), a certified industrial hygienist appeared claiming they have expertise. Many of (CIH), a certified indoor air quality profes- these firms can be found in the Yellow Pages or on sional (CIAQP), a certified indoor environ- the Internet. The follow-ing are several starting mentalist (CIE) and a certified mold remedia- points for finding a qualified expert: tor (CMR) are helpful if they have experi- • Referrals from people who have successfully ence, useless if not. addressed mold problems. • Authors of articles and booklets. 2.2. What the Expert Will Do • Bibliographies of scientific and medical litera- to Assess the Problem ture on mold. The works of leading experts are typically published, and many of them work in Assessing a potential mold problem at the mini- firms with good reputations. mum requires a visual inspection, source sam- • Industrial hygienists or your state health pling and when indicated, air sampling. The fol- department. lowing discussion focuses on situations other than water damage caused by floods and other YOU GET WHAT YOU PAY FOR. Although the catastrophic events. It applies to commercial, cost of a high-level expert in mold may seem institutional and residential construction.

23 While there is no national standard governing fun- Visible stains (red, pink, yellow and black) on the gal assessment and remediation, several organi- front side of the wallcovering can be indication zations and government agencies have developed that mold is growing behind the wallcovering. guidelines (see Appendix A, List of Guidelines and Some species of mold can produce by-products Resources for Assessment and Remediation of as a part of their digestive process, which can Fungal Contamination). The scope of the assess- migrate or diffuse to the front surface of wall cov- ment will vary depending on whether there is erings and produce these colored stains.77 already visible mold growth, if a musty smell is detectable and if building occupants have com- In most cases, the discovery of visible mold plained about health effects. The following out- growth warrants immediate cleanup and identifi- lines the steps usually taken during a mold con- cation of the underlying reasons for the growth. tamination assessment. Generally, if visible mold is present, additional air sampling is not necessary.31 BUILDING OCCUPANT INTERVIEWS. Often the site of the water damage is not obvious as it may Carpeting and other flooring, textiles, ceiling tiles, be hidden behind walls. Most mold problems, gypsum wallboard and ceilings, cardboard, press- however, occur on either the interior of the out- wood products, paper and other cellulosic sur- side wall or the adjacent wall that connects to the faces are also inspected. The inspector will look outside wall.1 Talking with building occupants both inside and outside the building for signs of and the building owner or manager can provide mold growth and water penetration, condensation valuable clues before a visual inspection of the and damage, for example: entire building and mechanical systems is done.40 • Landscaping appropriate for limiting water These interviews can also help establish a intrusion and dampness. hypothesis or several hypotheses, which provides • Roof condition and design (flat or pitched). a focus for the investigation.41 • Water stains near skylights, around ceiling fans, on ceiling tiles, in carpeting and on walls. VISUAL AND OLFACTORY INSPECTION. The • Leaking pipes. visual and olfactory inspection of building sys- • Loose or leaking toilet flanges. tems, components and materials for mold growth • Leaks at windowsills, wall penetrations and and water damage is the cornerstone of the diag- deck attachments. nostic process, particularly in seeking to identify • Missing, improper or improperly installed flashings. pathways of water or moisture entry and the loca- • Breaches in the roof, fascias,chimneys, and skylights. tion and number of sites within the building that • Windows and doors not properly flashed. have mold growth.42 Such inspections must be • Building cladding or trim not properly installed. thorough, consistent and based on experience • Wood touching the ground, allowing it to wick and knowledge of where mold grows, what condi- up moisture. tions lead to mold growth, and what mold growth • Negative drainage around the foundation. looks like and smells like.43 • Negatively pressurized building.

24 FIBEROPTIC EQUIPMENT. Fiberoptic equip- building material or component, for example, ment, such as a boroscope, which has a high plywood, studs or gypsum wallboard.46 Other intensity light, may be used to view spaces meters feature multiple scales. The Delmhorst behind ductwork or behind walls. If there is BD-2100, for example, includes a scale for gyp- active mold growth, often the inspector will be sum wallboard in addition to a wood scale and a able to detect the characteristic musty smell. The reference scale: HVAC system also is checked for damp filters and • Wood Scale – 6 percent to 40 percent moisture conditions as well as overall cleanliness.42, 43, 44 range. Useful for flooring and building material such as wood studs, floor joists and subfloors. MOISTURE METERS. Moisture meters that • Reference Scale – reads from of 0 to 100 on a detect, measure and locate moisture in buildings relative basis. Used on non-wood materials materials are rapidly becoming an important diag- such as concrete, plaster, and insulation. nostic tool for mold remediation and prevention.31 • Gypsum Scale – 0.2 percent to 6 percent Basically, there are two-types of moisture meters: moisture range. Used on gypsum wallboard.41 pin-type resistance meters and impedance, pinless or pad-type meters. Both measure the way Visit www.delmhorst.com for more information. moisture affects the electrical properties of the material being tested.45 The impedance, pinless and pad meters operate on the principle of electrical impedance, in which The most accurate results may be obtained from the electrical impedance of a material varies in the use of the pin-type moisture meters. The pins proportion to its moisture content. Pinless meters read only at their uninsulated pin tips, which allow use radio frequency signals to penetrate the the investigator to drive the pins into material at material being tested rather than pins. To meas- various depths and note readings at each level of ure and detect moisture, the two co-planar con- penetration. They also can detect if there is a ductive rubber electrodes mounted on the base of loss of adhesion of the loose wallcovering.46 As the instrument case are pressed onto the material the pins are removed the wallcovering will bulge being tested. The instrument measures the elec- or puff out to follow the pins being removed. trical impedance of this material by creating a low frequency alternating electric field between the The pin-type resistance meters work on the principle electrodes. The very small alternating current of direct current (DC) resistance measurement. For flowing through the field is proportional to the most porous materials, an increase in moisture con- impedance of the material. The instrument tent will result in a decrease in electrical resistance. detects this current, determines its amplitude and The resistance measurement meter has pin elec- displays the computed moisture value on the trodes connected to it. When the pins are inserted moving coil pointer meter or LCD display material. into the material being tested, the DC current passes The field penetrates the material being tested to a in a single line from one pin to the other, measuring depth of up to approximately 1 1/4 inch (30 mm) the decrease in the resistance. The higher the mois- for the pocket size instrument and up to 3 inch ture content, the lower the resistance. This change (75 mm) for larger impedance meter.45, 46 is translated into a moisture-related reading and dis- played on a moving coil or digital or diode display.45 As there is a wide variation in the nominal electri- These meters must be calibrated for each type of cal impedance of different material types, a good

25 quality moisture meter of this type should provide hypotheses and plan should be achieved prior to at least three selectable scales that are optimal sampling and is usually part of developing a for testing materials such as wood, timber; dry- scope of work for the remediation process (see wall, roofing; and plaster, brick. In addition to Section 3, How to Get Rid of Mold Once It’s these materials, one of these sensitivity scales Found). Sampling is done to confirm the following: should be suitable for the detection and location of • The identity of visible fungal growth elevated moisture in or behind a range of covering • Release of aerosols materials such as wall, floor, and ceiling tiles, sid- • Active mold growth ing, carpet tiles and laminated floor coverings.45 • Success of remediation procedures43

The impedance, pinless and pad meters are not One word of caution with respect to sampling: always accurate, but they can be useful for quick, Nearly all indoor air quality experts in the U.S. qualitative surveys to identify wet versus dry recommend spending only a minimal effort in col- spots in walls and floors over a large area. lecting and analyzing mold samples. One reason They also can help determine if further testing is that mold is everywhere in the environment and s required in certain spots. These meters are relying on sampling results alone to clarify the particularly susceptible to misinterpretation when problem rarely helps. Further, air sampling is working with laminated composites.40, 46 notoriously susceptible to “false negative results,” meaning that non-detection does not indicate that A recent study explored the association of mois- mold does not exist. In short, if mold is visible, ture measurements and microbial levels. The there is a problem that needs to be promptly results showed that when water damage was addressed.48 With that being said, the following ongoing during the investigation, moisture meas- further details source and air sampling, the two urements are sufficient to estimate the risk of fun- primary methods used to evaluate mold problems. gal contamination and growth. However, if drying of moisture damaged-materials has begun, or SOURCE SAMPLING. Source sampling is useful moisture conditions in the materials are varying to document that discoloration or deposits on in a wide range over time, then direct-counting surfaces actually represent fungal growth or spore methods for spores are most appropriate for accumulation and is done to confirm olfactory assessing the level of biocontamination.47 indications of mold growth. These samples are usually collected from visibly moldy surfaces by OTHER TYPES OF METERS. Some investigators scraping and cutting materials with a clean tool also use sound meters and infrared sensors to and putting them into a clean plastic bag. measure air leakage, on the assumption that Surface samples are usually collected by wiping a where air is free to enter a building so is water measured area with a sterile swab or by stripping or moisture.40, 46 the suspect surface with clear tape.31 These samples are analyzed under a microscope. SAMPLING. The strategy for collecting samples Surface sampling is less destructive than bulk involves developing hypotheses (as noted above) sampling, which requires removing a piece of the and then designing a plan that will allow testing building material or component on which the of the hypotheses.31, 32 Agreement on the mold is growing.

26 AIR SAMPLING. Air sampling often is employed other mold and bacteria may result in its being to document what type(s) and amount(s) of mold killed off by other organisms in the sample.30, 49 spores or hyphae are in the air, to assess the cause of symptoms reported by building occu- SAMPLE ANALYSES. The primary methods of pants or to gauge the level of contamination evaluating the samples of fungi are to isolate the throughout the building if there is evidence from fungi in a laboratory culture and examine the cul- the visual inspection or bulk sampling that the ture by microscope. Other approaches also are HVAC system has been contaminated.31, 40 Air used, such as analysis of mold metabolites sampling for fungi particles is complicated by their ethanol, ergosterol50 or glucan concentrations as diversity in size, shape, density and surface features. estimates of fungal biomass. In addition, This form of sampling also is prone to false posi- immunoassays are under development for meas- tives. The ACGIH emphasizes the importance of a uring some specific fungal allergens.32 well-designed sampling protocol, reliance on carefully collected baseline data for comparison, and Conventional testing and analysis methodologies collecting a sufficient number of samples to ensure rely heavily on human evaluation and are depend- results are not due to random chance.32 ent on the degree of the analyst’s expertise and experience. In addition, techniques such as culti- Most common airborne mold spores are collected vation are time-consuming, while others such as using impaction into agar or an adhesive-coating microscopy are labor-intensive and subjective. transparent surface (spore trapping). Culture- Polymerase Chain Reaction (PCR) is a new tech- based analyses tend to underestimate actual fun- nology that holds great promise for speeding up gal concentration because many spores are either and increasing the accuracy of identifying micro- not viable or are unable to grow on the culture bial organisms by keying in on the organisms’ medium. Spore trapping allows accurate count- DNA.51 A recent study demonstrated that PCR is ing of total fungal spores and identification of useful for directly detecting Stachybotrys char- some spores, but many spores such as tarum on gypsum wallboard without intermediate Penicillium sp. and Aspergillus sp. cannot be cultivation, and that it might be possible to distin- identified by microscope.32 Stachybotrys char- guish between toxin and non-toxin producing tarum also is not easily captured in air samples, strains.52 As of this writing, the test kit for as its spores when wet are sticky and not easily Stachybotrys chartarum is just making its way to aerosolized. Further, its inability to compete with the commercial market.53

Conventional testing and analysis

methodologies rely heavily on

human evaluation and are

dependant on the degree of the

analyst’s expertise and experience.

27 SEASONAL VARIATIONS. When assessing a mold others non-viable (dead spores, toxins and submi- problem, the inspector also should be aware of the cron particulate antigens); and susceptibility to potential effects of seasonal variations on the build- microbial agents varies widely among humans.54 ing. For example, inspection and testing may find a Analysis and microscopic identification of mold great deal of moisture in the drywall or wall cavity spores and colonies requires considerable expert- during the cooling months but may find the oppo- ise and should be done only by a qualified micro- site is true during the heating months. If the bial laboratory with specific expertise and experi- assessment is done during the heating months, ence in identifying fungi. The American Industrial there is a temptation to assume that moisture intru- Hygiene Association (AIHA) offers accreditation to sion is no longer a problem and all that needs to be microbial laboratories. The AIHA’s list of accredit- done is cleaning up any visible mold. Do not be ed labs is available at www.aiha.org. fooled! Even though testing may not demonstrate high moisture levels at that exact moment, evidence The presence of a few or trace amounts of fungal of mold is sufficient proof that at some point during spores in bulk/surface sampling should be consid- the year there is enough moisture for a long enough ered background. Air samples in particular are eval- period of time to support mold growth. The source uated by looking at the indoor/outdoor ratios of of that moisture must be found and corrected in mold levels and types, and the presences of indica- order for any remediation efforts to be successful. tor species in the indoor environment. Keep in mind See Section 1.2, Overview of Mold in Building and that even with excellent assessment and consulting Home Interiors, for details on sources of moisture with epidemiological and medical experts, the rela- condensation. tionships between sampling data and adverse health effects are difficult to determine.54 2.3. Testing Criteria and INDOOR/OUTDOOR RATIOS. A comparison of Results concentrations and species composition of the Also as of this writing, there are no government collected samples is used to assess indoor/out- standards or guidelines for interpreting microbial door ratios. In indoor environments without a testing results so there is no way to deem defi- mold problem, the number and types of mold nitely that a building is either “safe” or “unsafe” found in the indoor air are similar to the outdoor for building occupants.48 The reasons include the environment. This means that the source of mold absence of exposure baseline data for various inside the building is the outdoor environment. If types of mold and other microorganisms in indoor fungal concentrations indoors are consistently environments; the absence of epidemiological and significantly higher than outdoors, or if there data relating bioaerosol exposure to adverse is significant evidence of species in the indoor health effects; the sheer number of microbial samples that are not found in the outdoor sam- agents in the air, with some being viable and ples, then an indoor source is indicated.40

If the assessment is done during the

heating months, there is a temptation

to assume moisture intrusion is no

longer a problem.

Don’t be fooled! 28 Indoor fungal growth may also be present where the component of airborne fungi and detection of this indoor concentrations are less than or equal to the mold species is not as rare as previously thought. outdoors. Thus it is important to look at the compo- This study also offers comparative information on sition of the sample, that is, what species of mold common culturable airborne fungi in the US that are found in the samples. Proper identification can be used to better interpret bioaerosol sam- requires identifying the type of mold to the species ples. It is the largest study of airborne indoor and level. For example, limiting a report of Clado-spori- outdoor fungal species and concentrations con- um sp. to the genus level may lead investigators to ducted with a standardized protocol to date.28 assume the levels indoors are the similar to outdoors, with no particular indoor problem present. INDICATOR ORGANISMS. Fungi whose presence If the samples were identified to the species level, is indicative of excessive moisture and a potential the investigators would have found Cladosporium health hazard – for example, a species with known herbarum to be dominant outdoors and Clado-spori- allergenic, irritant or toxigenic properties that is um sphaerospermum indoors, with the latter indicat- uncommon in outdoor environments – are called ing an indoor source.32 indicator organisms. The mere presence of a few spores should be interpreted with caution, but it According to a recent study, the most common does not necessarily indicate that the building culturable airborne fungi, both outdoors and occupants are exposed to sufficient levels to cause indoors, and in all seasons and regions in the US, health effects. Further, indicator species are not were Cladosporium, Penicillium, nonsporulating the only fungi that can cause problems for building fungi and Aspergillus. As noted in Section 1.5, occupants, so investigators should consider these Different Types of Indoor Molds, the researchers findings as only an indication that there may be conclude that Stachybotrys chartarum is a normal mold growth in the indoor environment.32

Researchers have concluded

the Stachybotrys chartarum is a

normal component of airborne

fungi and detection of this mold

species is not as rare as

previously thought.

29 Section 3. How to Get Rid of Mold

Successful remediation and restoration of a build- Before a remediation effort is started, proper ing or home with mold can be accomplished with- assessment should be completed and a clear out taking drastic steps as reported by some scope for the remediation work developed. news media. See Section 2, How to Tell if a Remediation procedures depend on the extent of Mold Problem Exists, and Section 4.1, Eliminate the mold growth, including the following: Sources of • Amount of water to be removed and extent of Moisture, First and foremost, drying (if needed) in the case of structural leak- for more age, water pipe breakage or failure of septic information. the source of and other building systems. • Type of materials on which the fungi is growing. moisture must be Even though it • Size of the area impacted. is tempting to found and eliminated. • Degree to which the fungi have degraded the clean up mold materials for use as a food source. without the help of an expert – don’t, especially if the area is larger than 10 sq. ft. Mold can look Only specially trained personnel should undertake dead, but in actuality the spores are still very remediation, especially with mold infestation capable of spreading and colonizing other build- affecting areas larger than 10 sq. ft. (see Section ing materials. Without proper containment and 2.1, Finding a Qualified Expert).31, 55 Remediation removal, the risk of spreading mold spores also requires a great deal of professional judg- throughout the building is very high, not to men- ment. Essentially, the process is accomplished in tion an increased risk to the workers cleaning three steps: up the mold infested area of inhaling sufficient 1. Find the underlying cause of water intrusion number of mold spores that may possibly cause and/or the moisture and eliminate or control it. health problems. See Section 4.1, Eliminating Sources of Moisture, for more information. While there are no set standards, a number of 2. Remove porous materials on which the mold is organizations have provided guidelines (see growing, especially if the growth is extensive or Appendix A, List of Guidelines and Resources for the materials cannot be adequately cleaned. the Assessment and Remediation of Fungal 3. Clean the surfaces of non-porous and semi- Contamination). According to the New York City porous materials on which mold is growing as Department of Health Guidelines for Assessment long as they are structurally sound. and Remediation of Fungi in Indoor Environments, the goal of a mold remediation is “to remove or As in Section 2.2, What the Expert Will Do to clean any contaminated materials in a way that Assess the Problem, the following discussion prevents emission of fungi and dust contaminated focuses on situations other than water damage with fungi from leaving a work area and entering caused by floods and other catastrophic events. an occupied or non-abatement area, while pro- One note about water damage caused by these tecting the health of workers performing the events, however, is that any water infiltration abatement.”31 should be addressed as soon as possible.

30 Section 1. Who, What, Where, When, Why’s of Mold

3.1. Cleaning, Removing Fungi in Indoor Environments identify five levels Building Materials of contamination: • Level 1: Small isolated areas (10 sq. ft. or less), such as ceiling tiles and small areas on walls. Decisions about cleaning and removing building • Level 2: Mid-sized isolated areas (10 to 30 sq. materials depend on the type and condition of the ft.), such as individual gypsum wallboard panels. material (amount of degradation) on which the • Level 3: Large isolated areas (30 to 100 sq. ft.), mold is growing and the extent of mold growth. such as several gypsum wallboard panels. Except where noted, the following discussion is a • Level 4: Extensive contamination (greater than consensus of the steps outlined in the guidelines 100 contiguous sq. ft.). and resources listed in Appendix A, List of • Level 5: HVAC system. Guidelines and Resources for Assessment and Remediation of Fungal Contamination. POROUS MATERIALS. Porous materials, such as gypsum wallboard, ceiling tiles, insulation, carpet- An immediate response ing and textiles that have extensive mold growth must be removed. Contaminated wallcovering, (within 24 to 48 hours) by a whether porous or not, should be removed, firm specializing in water bagged, and taken to the landfill. If the mold growth is not extensive – that is, less than 10 sq. remediation and a thorough ft. of the wall surface is affected, and the mold has not infiltrated or degraded the wall surface – cleanup, drying and/or then the wall surface may be thoroughly cleaned removal of water-damaged by washing them with a dilute solution of biocide and detergent or vacuumed with equipment fitted materials will prevent or limit with high efficiency particle air (HEPA) filters. mold growth. Another recommended cleaning solution is comprised of two cups of household bleach per one gallon of water. A diluted bleach solution, howev- Wallcoverings per se are not specifically er, is not recommended for the initial wash of wall addressed in these guidelines. The safest or wall surface, because the spores may be course is to follow guidelines for removing mold bleached and become difficult to see, and as a from porous materials. result they may not be removed. Wash the wall area with a detergent solution first, then, wash The New York City Department of Health with the bleach solution. Once cleaned, the area Guidelines on Assessment and Remediation of should then be monitored for mold growth.

An important reminder: If the

moisture source is not eliminated,

mold growth will reoccur.

31 Caution: Do not mix cleaning solutions as hazardous gases NON-POROUS AND SEMI-POROUS MATERIALS. Non-porous materials (metal ductwork, metal studs, may be generated. Also, vinyl flooring, glass, fiberglass and plastics) can be diluted bleach or other readily cleaned. Slightly porous or semi-porous materials (wood and wood-pressed products, stone cleaning solutions may and concrete) that have visible mold growth may be reusable depending on the depth the mold growth discolor flooring or carpeting; has penetrated the building material or component. therefore, care should be Cleaning is accomplished by vacuuming using equipment with HEPA filters or direct air exhaust to taken to protect adjacent the outdoors, washing with a dilute solution of bio- surfaces. cide and detergent, or cleaning, thorough drying and repainting. Mold growth on furniture may be removed by refinishing.55

If the walls are wet or extremely damp, will not HVAC SYSTEM. By and large, the procedure for dry or have become soft from water damage, the remediation is the same for HVAC systems as for wallboard with the wallcoverings attached should the rest of the home or building. Application of be removed to limit mold spore exposure. In biocides as a substitute for removing microbial severe cases, studs and insulation may have to be growth and settled biological materials is not replaced. Replacement of drywall will eliminate acceptable. Contaminated porous materials in the need to wash and bleach the wall. It also the HVAC system must be removed down to the will provide a new, sound surface for reinstalla- bare (underlying) metal and appropriately discard- tion. A respirator or protective facemask should ed. Full containment procedures should be be worn during wallcovering and/or drywall implemented when removing extensive areas of removal. See Section 3.2, Specific Personal porous materials.55 Protection and Containment Guidelines, for 56 additional details. BIOCIDES AND ANTIMICROBIAL AGENTS. Biocides are chemical or physical agents that kill In addition, porous materials not supporting or inactivate microorganisms, and antimicrobial active mold growth can still harbor mold spores agents are compounds used to suppress micro- and particles from other sources. Where appro- bial growth.35 Although they may be useful in priate, these materials also should be thoroughly removing and preventing fungal contamination, cleaned and monitored. If porous materials have their use should be carefully considered; for absorbed odors, removal may be necessary to example: complete the restoration of the building. • The use of gaseous ozone or chlorine dioxide Carpeting and drapes that can be removed for for remedial purposes is not recommended, as thorough cleaning and drying may be salvage- both compounds are highly toxic, contamina- able. Valuable books and papers sometimes can tion of occupied spaces may pose a health be rescued by fumigation, followed by freeze- threat and the effectiveness of these treat- drying and vacuuming the residual particles.55 ments is not certain.31

32 • Some agents are designed to treat certain polymers to bind to the calcium hydroxide to groups of microorganisms and not others. keep it from rapidly degrading when the com- Suppression of one species may give others an pound is exposed to ambient air. When applied advantage.57 to hard surfaces in a building, such as walls, ceil- • Most disinfectants and sanitizers are approved ings and floors, or incorporated as a part of for use on previously cleaned rather than solid these building products during the manufacturing surfaces, but for thoroughly cleaned surfaces, process, this new technology has the proven a biocide may not be needed, as killing mold ability to kill infectious agents and fungi on con- does not necessarily destroy their antigenic or tact and inhibit their spread for many years, while toxic properties.57 being safe for building occupants.58 While the cost of this new technology is very expensive, it BIOCIDES, ANTIMICROBIAL AGENTS AND is being reviewed by wallcovering manufacturers. WALLCOVERINGS. Manufacturers of wallcover- Vinyl wallcovering manufacturers incorporate a ing adhesives and primers typically incorporate biocide (mildewcide) into the vinyl formulation of biocides and antimicrobial agents into their for- their wallcovering. mulas to protect walls and the wallcoverings from mold growth. These biocide systems, also called Another strategy being offered by primer manu- fungicides or fungistats, are designed to prevent facturers is a primer that creates a barrier microbial contamination and mold infestation between the wall and wallcovering backing, which “in-the-can” and/or in the dried adhesives. the mold cannot overcome. Primers also help to protect the drywall face when wallcoverings are One new technology of note that is just making its removed. Regardless of the type of wallcovering, way to market is a preventive and remedial sys- proper wall preparation and application of a tem that uses calcium hydroxide, a naturally primer is essential not only for quality wallcover- occurring biocidal agent. This in itself is not ing installation but also for preventing mold unique, as calcium hydroxide has been used for growth. See Section 4.2, Select Materials and years in this capacity. What is unique is this tech- Finishes to Prevent Mold, for more about prepar- nology uses selected microencapsulating ing the wall for a wallcovering.

An important note: Any use of biocides

(mildewcides) and antimicrobial agents, whether

they be stand-alone products or incorporated into

wallcovering adhesives and primers, should

complement proper water and moisture control

and regular cleaning and maintenance, not

replace them.57 If the moisture source is not

eliminated, mold will grow.

33 3.2. Specific Personal • Source containment for minimal contamination Protection and Containment requires no special isolation of the area. Guidelines Removal is straightforward and relatively simple, such as placing a moldy ceiling tile into a Before any remediation work is begun, appropri- plastic bag, sealing the bag and removing the ate personal protection and containment proto- bag from the building. As wallcoverings are cols should be established. The larger the area removed from the wall, carefully roll inward of fungal contamination, the more stringent per- (mold area inside) so that the mold-infested sonal protection and containment requirements area is contained and worker exposure is mini- should become. mized. Removed wallcoverings can then be bagged and taken from the building. These Personal protective equipment (PPE) may include products can then be added to a landfill.56 gloves, eye protection, protective clothing cover- • Local containment involves constructing an ing both head and shoes, and respiratory protec- enclosure with two layers of polyethylene film tion in accordance with OSHA’s respiratory pro- supported on a wood-stud frame. A HEPA tection standard (29 CFR 1910.134). Many states vacuum nozzle is used to create sufficient neg- also have their own respiratory protection stan- ative pressure within the enclosure to ensure dards under state-operated OSHA plans. For containment of bioaerosols. example, California, Oregon and Washington • Full-scale containment is commensurate with each have requirements that exceed those of an asbestos abatement program and consists OSHA, but only apply to work in those states. of a critical barrier to isolate the contaminated Respiratory protection may range from disposable area from the clean or occupied area of the respirators to full-face respirators with HEPA building; negative pressure created with a cartridges. Few data are available on exposures HEPA air filtration device, such as a negative 59, 60, 61 occurring during remediation. Decisions air machine; and a decontamination unit for on what PPE will adequately protect workers entry and exit of the remediation area. requires experience and professional judgment Contaminated debris is double-bagged and and may be obtained from occupational passed through this area for HEPA vacuuming physicians, toxicologists, respiratory protection before being disposed. experts, and health and safety professionals.55 Bagged debris, even from extensive fungal con- One of the most important goals is to minimize in tamination, can be disposed of in a landfill as if the case of minimal contamination and, in the the contents were moldy compost. Also, dust case of moderate and extensive contamination, that may have settled outside the containment prevent the dispersal of dust and mold spores. area should be removed with HEPA vacuuming The ACGIH identifies three levels of containment: and damp wiping followed by thorough drying.

34 3.3. Verifying Successful • Confirmed by sampling, including Remediation outdoor/indoor ratios. Results of surface sampling should be similar to other well-main- Success of the remediation process can be tained buildings or on construction and finish- judged by the following: ing materials in the same geographic area. • Visual inspection to ensure all of the contami- • Ability of people to re-occupy the space with- nated building material or component is out complaining of adverse health effects or removed. physical discomfort.

If mold should begin to grow again, then

likely the source of water or moisture

has not been found or adequately controlled

or eliminated. These sources must be

addressed to keep mold from

re-establishing colonies.

35 Section 4. How To Keep Mold From Growing

In order for mold to grow, it needs optimal temper- 1. Building tightness, which does not allow mois- atures, usually between 40 degrees F and 100 ture to escape to the outdoors. degrees F (4 degrees C and 38 degrees C), nutri- 2. Liquid water infiltration from outside as a result of ents in or on the building material or component, a leaky building envelope or structural failure. fungal spores that settle on the building material or 3. Moisture condensation on cold surfaces of component, and moisture, usually 70 percent rela- building materials or components, which origi- tive humidity or higher at the surface of the build- nates from water vapor inside or outside the ing material or component. For all practical pur- building. poses, all of these conditions, except moisture lev- 4. Moisture generated within the building by the els, are met in nearly every home and building.62, 63 occupant and the occupant’s activity.

In existing homes and buildings, an effective line These factors do not act independently of one of defense is first and foremost to eliminate the another. In fact, there is a great deal of interac- source(s) of moisture and air infiltration, and section. The keys to eliminating moisture sources ond is to ensure that water vapor in the wall cavi- include the following: ty can escape to the building’s interior through • Designing and constructing the building enve- the wall surface. In new homes and buildings, the lope and wall systems to prevent water and/or key is to design and build the structures to pre- moisture from entering the building while at the vent favorable conditions for mold growth in the same time providing a way for any accumulat- first place. In both cases, choosing the right walled water and/or moisture in a wall system(s) to covering in terms of its permeability and properly either drain to the exterior of the building or preparing the wall surface can strengthen these evaporate. lines of defense in cooling climates. • Knowing how and when to use vapor barriers • Properly managing air pressures and airflow 4.1. Eliminate Sources of inside the building. Moisture • Positive pressure is preferred to negative pressure. Trying to clean up a mold problem without first • Maintaining indoor relative humidity below 60 solving the fundamental cause of the moisture percent. problem will prove to be both futile and costly. The primary places to look for the cause of mois- BUILDING TIGHTNESS. The most critical areas of ture intrusion is the building’s HVAC and envelope the building envelope are gaps around the win- (roof and wall) systems. Insurance company dows and doors, joint openings at roof, ceiling or records clearly show that these two building floor lines, and soffit or wall vent systems. These systems comprise the majority of all post-con- areas are the most likely openings and are construction litigation claims against design teams, venient pathways for air leakage and moisture especially those related to moisture intrusion intrusion into a building. Although good positive problems.48 pressurization within the home or building can As described in Section 1.2, Overview of Mold in typically overcome leakage, these areas should Building and Home Interiors, the following are the be sealed. A tightly sealed home or building will four primary factors that influence moisture levels minimize air leakage and reduce the amount of air in buildings: required by the HVAC system to maintain positive

36 pressures, which saves energy.7 There are less ment techniques to determine aw. Many investiga- common conditions where positive building pres- tors try to use moisture content as a direct indica- surization would not be desirable, such as homes tor, but this is related indirectly to aw. Moisture or buildings with a high internal moisture load, but content is the weight of water in the material divid- that is not typical. This publication addresses ed by the weight of the material in a dry condition. only typical homes and buildings. It is expressed as a percentage. For example, water activity of 0.80, which is prime for mold

WATER INFILTRATION. Water infiltration from any growth, corresponds to the moisture contents of of the many possible sources must be prevented. the following building products: brick (0.1 percent Here are some steps: to 0.9 percent), gypsum wallboard (0.7 percent), • Seal leaks in the building envelope and repair cement (1 percent), wallcoverings (11 percent) and improperly installed and water-damaged build- soft wood (17 percent).64, 66 ing components. As a result of these difficulties, many advisory • Install proper flashing where required (particu- groups recommend using relative humidity to indi- larly roof penetrations, roof junctions, window cate microbial growth potential. The key, howev- and door assemblies, chimneys and deck er, is to measure the relative humidity adjacent to attachments) in order to direct water away the surface of the building material or component from the building and manage the flow of water not the ambient relative humidity in the room. near critical building elements. Although room relative humidity may keep most • Install an effective rainwater barrier and drainage building materials fairly dry, it does not eliminate plain on the exterior side of the stud cavity, which the possibility of microbial growth as cold spots can take a wide variety of forms and can be a or water intrusion may allow the relative humidity part of the cladding system or a separate element of air adjacent to the building material or compo- of the wall assembly, depending upon design and nent to exceed 70 percent.66 building components. • Improve the drainage around the foundation to Relying on relative humidity has some limitations prevent groundwater, including capillary water as well. There is only limited information available movement through the building materials, from on the influence of fluctuating humidity on micro- entering the building. 64,65 bial growth in building materials. According to • Use building code compliant components that recent studies, durations of the wet and dry peri- effectively refuse water and moisture entry ods are critical for fungal growth in fluctuating • Ensure that good building practices are fol- conditions, because the time need for prolifera- lowed and that all building envelope systems tion at high relative humidity is longer and the are properly installed in accordance with code growth rate lower than on the constant favorable and manufacturer’s recommendations. circumstances.67 Seasonal variations and day-today variations, in some cases, can cause fluctuat- CONTROLLING CONDENSATION. Although mois- ing growth periods for the mold. The best guid- ture activity is the best indicator of potential mold ance is to maintain indoor relative humidity con- growth, there are presently no direct field measure sistently below 60 percent.

37 VAPOR AND AIR BARRIERS. Effectively con- discussion below) positioned between the air trolling condensation within wall systems requires barrier and the insulation on the external portion understanding how condensation occurs in differ- of the building envelope. Other considerations ent climates and in different seasons. Effective and strategies follow: control also requires designing the wall system • Install appropriate insulation to prevent large and implementing appropriate strategies to temperature differences between the air and accommodate the climate and change of sea- surfaces. sons. It is suggested that a current moisture con- • Whether or not to install a vapor barrier has trol handbook be consulted to inform the reader been a point of confusion and debate not just of the latest ideas for moisture control. Typically, among designers and builders but also among wall systems consist of the exterior wall, metal or the various building codes. After considering wood stud framing, air barrier, vapor barrier (if the various opinions, the most effective used), insulation, gypsum sheathing, gypsum approach appears to be not installing a sepa- wallboard and a wallcovering or paint. The pri- rate vapor barrier. See Appendix D, Standard mary variances in this structure that are depend- Test Method and Calculation of Permeability, ent on the climate include the following: for a discussion of computer modeling of wall • Location of the air barrier, which should be construction. Moisture trapped between two located on the warm side of the building enve- materials that act as vapor barriers cannot lope; that is, adjacent to the exterior wall in escape and thus condenses inside the ceiling warm, humid climates and adjacent to the inte- or wall at the cold surface. If a vapor barrier is rior wall in cold climates. used, extreme care should be taken in deter- • Whether a vapor barrier is used and its location mining which method to use. between the air barrier and insulation. • Use a permeable wallcovering or permeable • Type of wallcovering or paint. See Section 4.2, paint on internal surfaces. Select Materials and Finishes to Prevent Mold, • The HVAC system must maintain a net positive for more information. pressure with respect to the outdoors to keep unconditioned outdoor air out of the home or building. HOT, HUMID CLIMATES. The goal is to keep • Avoid excessive cooling of interior spaces moisture in the outdoor air from reaching the first below the average, monthly, outdoor dew point cool surface inside the building envelope (referred for the area in which the home or building is to as the first plane of condensation). If the mois- located. This may not be possible in some ture is allowed to further enter the wall system, locations, especially in summer. At these it will condense. In this climate, the air barrier times, proper insulation, correct location of air should be located immediately adjacent to the and vapor barriers (if used) and maintenance of exterior wall with the vapor barrier (if used, see pressure relationships are vital.7, 63, 65, 68, 69

38 COLD CLIMATES. The goal is to keep warm, protection against condensation during the heat- moist air in the indoor environment from flowing ing season by reducing the vapor diffusion into outward through cracks and holes in the building the wall assembly to an acceptable minimum. envelope. As the air nears the outer boundary of But in the cooling season, the low vapor the home or building it cools, the relative humidity permeability of the vapor barrier reduces drying rises because cooler air has a lower moisture- potential and as a result may trap moisture in the holding capacity. The result is moisture conden- wall assembly. sation in the wall cavity. In this climate, the air barrier is located adjacent to the interior wall with This dilemma has resulted in the development of the vapor barrier positioned between the air barri- innovative vapor barriers or retarders, which are er and the insulation. Other considerations and now just emerging and may not yet be commer- strategies include: cially available. These barriers and retarders may • Install appropriate insulation to prevent large provide more flexible water vapor control than tra- temperature differences between the air and ditional materials. For example, the “smart” surfaces. Make certain that insulation in exte- retarder (a nylon film 50 µm or 2 mil in thickness) rior walls is adequate to prevent thermal bridg- takes advantage of the inversion of temperature ing and to minimize the development of cold and humidity levels from winter to summer. In spots on internal surfaces. winter, the air is warmer and more humid inside • A vapor barrier should be installed in cold cli- the building and in summer, the air is warmer and mates, but make sure it is installed on the more humid outside. When the ambient humidity warm side of the wall between the drywall and rises outside, the “smart” retarder adapts its the studs. Carefully consider the materials vapor permeability by opening its pores when used to make sure the vapor barrier has the good drying conditions prevail. It accomplishes proper resistance or moisture permeability to this by absorbing water from the air, which then control moisture flow through the wall system. opens its molecular pores.70 • Use source control and dilution ventilation to reduce indoor moisture levels below those that The “smart” vapor retarder does have limitations, allow condensation to occur. Provide good air however, and may not be as effective in hot, circulation to keep interior surfaces at an even, humid climates where high outdoor humidity lev- warm temperature.65, 68, 69 els prevail. The higher humidity may increase the “smart” vapor retarder’s permeability to such an MIXED CLIMATES. Many parts of the U.S. may extent that it may not be able to reduce vapor dif- be categorized as being in a mixed climate: cold fusion sufficiently. The same may be true in all and dry in the winter and hot and humid in the climates for buildings with exceptionally high summer. Placement of the vapor barrier follows indoor humidity levels, such as an indoor swim- the advice for cold climates; that is, on the warm, ming pool. Short peaks of high indoor relative winter side of the wall assembly.13 humidity, such as may occur in kitchens and bathrooms, do not affect the “smart” retarders Conventional vapor barriers may provide effective performance.70

39 Figure 4.1 shows a map of the areas in the U.S. • Design the system to supply sufficient pre-condi- that the U.S. Department of Housing and Urban tioned and filtered air to remove excess humidity Development has designated as a cooling (humid and contaminants such as mold spores from and fringe) climate. make-up air and to prevent intrusion of outside air through the building envelope. Figure 4.1 Humid and Fringe Climate Map16 • Design the system to properly manage moisture loads. • Design the system to properly to maintain the building at a slightly higher pressure relative to the outside, which will force air to flow out of the building through joints and cracks rather than allowing outside air to flow into the building.7, 71

4.2. Select Materials and Finishes to Prevent Mold Although much of the recent attention has been Fringe Climates focused on how molds possibly can harm people, Humid Climates mold also can cause building materials, furnishings and the building structure itself to premature- Hawaii ly degrade and/or corrode. Premature failure or Puerto irreversible damage of the building envelope, inte- Rico rior walls, ceilings, floors, carpets, wallcoverings, HVAC system components and furnishings can lead to increased maintenance and operation costs.64 HVAC SYSTEM. As described in Section 1.2, Overview of Mold in Building and Home Interiors, Today, an effective strategy for controlling con- improper interaction between the HVAC system and densation and preventing mold growth is to the building envelope can be a major player in cre- design wall systems and select materials and fin- ating favorable conditions for mold growth. While ishes that allow air and moisture to move freely the HVAC system itself is not a source of moisture, through the wall system. Using highly permeable its design and how well it is operated and main- materials on the cold side and low permeability tained has a direct bearing on its effectiveness in materials on the warm side of the wall system preventing moisture intrusion and condensation. maximizes vapor pressure diffusion from the wall, The following are some general guidelines: meaning that water vapor inside the wall system • Design the room air conditioning supply air grille will migrate from the wall cavity into the interior or outlet so cool air does not blow directly on the space. Recall that operating a building with wall or ceiling, thereby maintaining the tempera- slightly positive pressure relative to the outdoors ture of the wall surface as high as possible and and using an external air barrier encourages dry minimizing the possibility of moisture condensa- indoor air to flow through the wall structure tion on or behind the wallcovering. toward the outdoors. This has the advantage of

40 lowering the relative humidity inside the wall materials provide a nutrient source. Structural prop- structure. So, by combining these strategies, erties of a building material’s surface can be a factor moisture is forced from the walls while dry air is as they have a tendency to change during the serv- encouraged to travel into the wall system toward ice life due to environmental factors, such as ultravi- the outside.63 olet radiation and moisture. These changes make building materials more susceptible to mold growth, A key component of this strategy is selecting the because as they degrade, their organic components proper wallcovering that balances performance become available as a nutrient source.72 characteristics and permeability. Here are some guidelines: A recent study looking at the response of different • Any wallcovering covering can be installed in a building materials to mold contamination at vari- dry building. ous relative humidity levels found that stone- • Questionable walls should use a permeable based materials, including cement screed, gyp- (breathable) wallcovering or perforated sum wallboard and concrete, required longer (“microvented”) wallcovering. exposure time at higher relative humidity for initial fungal growth than wood-based materials, including particleboard, fiberboard and plywood made As a compromise, the interior of softwoods. Concrete was less susceptible to surface of the exterior walls in fungal growth, probably due to high alkaline properties in the material. The investigators also found cooling climates should be installed that all building materials tested, which also included insulation products, were susceptible to with permeable (breathable) or mold growth at or above 90 percent relative microvented vinyl and interior walls humidity and temperatures at or above 59 degrees F (15 degrees C).72 with any variety of wallcoverings.

See Section 4.1, Eliminate Sources 4.3. Proper Surface of Moisture, for more information. Preparation Proper surface preparation is not only essential Also, using high-quality materials and finishes are for quality wallcovering installation but also for important, because they generally will not degrade preventing mold growth regardless of whether the as quickly as lower quality products. Different build- building is new or existing. The wall surface ing materials have different levels of susceptibility to should be clean, dry, structurally sound and free fungal growth, depending on the amount of water of mold, grease and other stains. In new con- activity the material can support (see Section 1.2, struction, ideally sufficient time should be allowed Overview of Mold in Building and Home Interiors), for the building to dry out before drywall and wall- the amount of organic matter contained in or on the coverings are installed. The actual moisture of the surface of the product, other structural properties, drywall may vary with relative humidity in the and the rate of degradation in the presence of mois- area. Moisture content of a new drywall may be ture. Organic materials, such as binding agents and as high as 15 to 18 percent as measured by a auxiliary substances, that are added to the inorganic moisture meter in a hot and humid climate during

41 the cooling season.56 In other areas of the coun- Each type of surface needs to be treated accordingly: try, normal moisture content is typically under six percent. Care should be to ensure that high NEW DRYWALL. Make sure the drywall is free of moisture content in the wallboard is due to rela- contaminants such as dust, dirt and mildew and tive humidity and not a leaky building or improp- has had enough time to dry out. Joints and erly stored building material. spackled areas should be thoroughly cured and sanded smooth. Best results are obtained when In existing buildings, careful inspection of the wall the moisture content of the drywall is minimized. surface should be made and any mold should be Apply a good quality wallcovering primer. cleaned or removed in accordance with mold removal guidelines. If the area is less than 10 sq. NEW PLASTER. Allow at least 60 to 90 days for ft., then the area may be thoroughly cleaned. If new plaster to completely cure. Best results are the area is obtained when the moisture content of the plaster greater than 10 in minimized. If waiting for total curing is not pos- Wallcoverings should sq. ft., proper sible, the newly plastered walls should be washed removal proto- never be installed on with a zinc sulfate solution to neutralize the lime cols should be (two to four pounds of zinc sulfate per gallon of a wet wall. followed. See water) then prime the wall. Best results will be Section 3.1, obtained if a pigmented, acrylic wallcovering Cleaning, Removing Building Materials, for primer is used to decrease the porosity of the details. Also, if the walls are wet or extremely plaster and form a good surface to bond the wall- damp, will not dry or, have become soft from paper to the wall. water damage, then the wallboard should be removed and new drywall installed.56 After the PAINT. Test painted surfaces for moisture sensi- wall surface has been cleaned, any mold stains tivity. Hold a wet sponge or cloth to the paint sur- should be sealed with a good quality stain killer face for 15 seconds and then rub the surface vig- primer/sealer. orously with a cloth. If little or slight amount of paint is removed, the paint should be sound. If Any mold stains should be sealed with a good all or a large quantity is removed, the surface is quality stain killer primer/sealer. If the area is moisture sensitive, which may result in failure. greater than 10 sq. ft., proper removal protocols If the wall is found to be moisture-sensitive, it should be followed. Again, see Section 3.1, should be sanded or washed with ammonia to Cleaning, Removing Building Materials, for remove the paint. All painted walls should be details. primed with a good quality wallcovering primer.

MASONRY. Wall surfaces should not exceed 5.5 Any mold stains percent moisture as measured by a moisture meter. It is best to seal the concrete with a water- should be sealed with proof sealer before applying a wallcovering primer a good quality stain and hanging the wallcovering. Surfaces should be sanded smooth and irregular surfaces smoothed killer primer/sealer. with drywall compound, plaster or other materials. Liner paper may be required.

42 OLD WALLCOVERING HAS BEEN REMOVED. 4.4. Good Practices – Keep Old adhesives can act as a food source for mold Materials and Work Area and make bonding to the wall surface uneven and Clean difficult. They should be removed by sanding or by use of an adhesive remover. Rinse the wall Keeping the work area and the wallcoverings and allow it to dry. If the wall shows any signs of clean is vitally important for preventing mold existing mold, it should be washed with a growth. For example, the water used to install water/detergent solution, rinsed with a wallcoverings should be potable water; that is, water/household bleach solution and then water that is clean enough to drink. Only water allowed to dry as described in Section 3.1, that is brought onsite by installers or obtained Cleaning, Removing Building Materials. As noted, from a secure source should be used. if the area in question is larger than 10 sq. ft., then proper removal protocols should be fol- Bringing water onsite or obtaining it from a secure lowed. Repair the wall as necessary, and prime source may at first blush appear to be very with a good quality wallcovering primer. demanding; however, invisible fungi and bacteria are everywhere. As described in Section 1.2, Wallcoverings can then be reinstalled using con- Overview of Mold in Building and Home Interiors, ventional methods and the recommendations and Section 1.4, Mold, Mildew, Fungi – What’s the noted above under New Drywall. Since, the dry- Difference?, mold can grow and multiply in moist wall may have been wet, the surface may have a and warm environments that provide organic greater tendency to peel or release some of the nutrients. paper when a double cut is made. Dry hanging, cutting the seam shortly after the wallcoverings Because spores are invisible, installers should has been applied to the wall or both seem to help take extra precautions to avoid using contaminat- with this problem. In addition, a thin coating of ed tools, water or materials. Even experienced adhesive in the peeled area seems to provide sat- installers have been known to keep water con- isfactory results.56 taminated with traces of adhesive from application rollers that have been soaking overnight or even over a weekend. This contaminated water PANELING. Sand or chemically remove all surface contaminants. Follow this step with a good quality becomes a good culture broth and a warm room adhesion promoting primer. Grooves should be becomes an incubator. Application rollers can filled then primed and/or an appropriate wall liner become grossly contaminated, and if these rollers should be used. Most wallcoverings will require are used, or if contaminated water is used to additional priming of the wall liner before installa- dilute adhesives, problems may occur. tion. See wall liner instructions for priming, installation and adhesive recommendations.17 In most jobs, being unaware of potential problems with the wall or wall surface or being careless will Specific installation instructions for any type of not cause damage to the wall from mold growth surface may be obtained from the wallcoverings since the adhesive dries quickly. The same han- manufacturer. dling, however, will contribute to problems with

43 walls that do not allow water or moisture to dissi- • Use a good quality wallcovering adhesive that pate and with wall surfaces that prevent fast dry- contains biocides. ing of adhesives. The difference is the walls’ • Apply the adhesive from factory-sealed contain- ability to absorb and retain moisture (see Section ers, and use new rollers. Alternatively, a pasting 1.2, Overview of Mold in Building and Home machine may be used instead of rollers. Interiors, and Section 4.3 Proper Surface • Do not soak rollers in water. Leave the rollers Preparation). Any source of excess moisture in the primer or adhesive or use a new roller should be corrected before installing or rein- each day. stalling wallcoverings (see Section 4.1, Eliminate • Use new sponges. Wash them completely in Sources of Moisture). running water and leave them to dry overnight. • Change the wash water frequently to limit possible contamination. The following suggestions will minimize or elimi- • Use dry sponges and clean, dry pails for fresh nate problems: water each morning. (Caution: Bleach may • Remove any old wallcovering and any residual cause natural sponges to deteriorate). adhesive. Wash any areas with visible mold with • Paper expands when it is immersed in water. a water and detergent solution. Wash again with Consequently, residential paper-backed prod- a water/household bleach solution. See Section ucts require booking; that is, folding the wall- 3.1, Cleaning, Removing Building Materials, for covering such that wet side is against wet side, details and wall surface limitations. Allow the in order to allow the paper to expand and washed wall to dry. Before installing the wallcov- reach a steady state. If the wallcovering is not ering, the wall surface should be dry, free of allowed to expand then seam overlapping will grease, staining markers and mold. Also, the occur. The best way to determine if a wallcov- wall should be structurally sound with no exces- ering should be booked, or not, is to follow the sive moisture or condensation. installation instructions. • If any wall area is not dry or structurally sound • Use the minimum quantity of adhesive that can for installation, then do not install the wallcov- do the job. Do not book non-woven and fab- ering. Alert the drywall contractor, general ric-backed products, unless stated otherwise contractor, building owner or homeowner as in the manufacturers directions, and leave the appropriate, and wait until the problems in the pasted wallcoverings open to evaporate water. area have been corrected before either starting Since mold can grow on the wet adhesive, the or continuing with the wallcovering installation. less adhesive and water on the wallcovering • Any dark stained areas should be treated with and the faster it dries, the better. a stain killing/blocking primer to prevent • Pasting the wall with adhesive for vinyl wall- stains from coming through the wallcovering covering and non-wovens may be an option. at a later time. Pasting the wall for paper products is not rec- • Use a primer with a biocide. Follow the manu- ommended. facturer’s instructions for application. Note • Pasting machines are routinely left “loaded” that some manufacturers require two coats of overnight. Ideally, they should be cleaned at a primer for mold protection. the end of the workday to limit contamination • Apply the primer from factory-sealed contain- or spoilage, especially if there is a high risk for ers, and use new rollers and trays. contamination at the installation site.

44 Buildings and homes, especially in

hot and humid climates, fail because 4.5. Design and Build It Right in the First Place satisfying building codes alone does The focus of this publication has been to provide not ensure that the combination an overview of what is involved in taking care of of design features selected for a a mold problem once it has occurred and to prevent problems in existing homes and buildings. particular structure and past Going forward, the ultimate prevention of mold strategies work together to prevent contamination is to design and build homes and buildings right in the first place. moisture and mold problems. Often

As emphasized through this publication, control- more design features than are ling moisture is the key to preventing mold prob- specified in building codes and new lems. The key to controlling moisture is understanding how building systems interact, and strategies are needed. designing and constructing homes and buildings to utilize that interaction to prevent water and moisture intrusion from the outdoor environment • Contradiction among fundamental forces, such while maintaining a comfortable indoor environ- as cost, schedule and quality, which influences ment with a constant relative humidity below decision makers throughout the design and 60 percent. construction process. During the design phase, cost is typically the biggest concern. Looking at why homes and buildings fail may Very often, the design team has little or no prove useful in determining what is required to input into developing the budget, yet the team design and build a successful building. Failures may be contractually obligated to redesign the can be attributed to following three factors: project at the team members’ expense if their • Building and home owners’ unrealistic expec- design exceeds the construction budget. tations of success and reliance on the con- During the construction phase, the primary tracting process and building codes to protect concern is scheduling, since controlling the their buildings from failure. In addition, many schedule is directly linked to controlling the building designers and contractors believe that project’s final cost. The general contractor is following established building codes and using often contractually obligated to finish a project strategies they have used before is enough to by a specific date or face assessment of dam- guarantee success. ages. Only at the punch list phase does quali- • Complexity of the building construction ty become a consideration and by then process and the failure of the design and con- changes become too costly or require too struction team to recognize the interrelation- much time to complete. Consequently, prob- ships between various technical disciplines. lems may not be corrected.5

45 To be successful, the building and home owner present different problems, and buildings should be and all members of the design and building team, designed and operated accordingly.73 including interior designers, drywall contractors During the design phase, the architect, the interior and wallcovering installers, must be aware of designer, the drywall contractor and the mechani- these factors and work together to mitigate them, cal engineer should collaborate closely to identify by being involved in the planning, design, con- and address critical design issues that will impact struction, finishing and commissioning of the not only energy usage but also control of mois- building. David Odom and his colleagues at ture intrusion and humidity within the building, CH2M Hill and Disney Development Company especially within the wall systems. Issues such developed a model to address and resolve indoor as exterior and interior wall finish permeability, air quality problems at each project stage, which vapor retarder (if used) type and location, air bar- can be summarized as follows: rier type and location, and weather barrier type • Establish specific design and construction and location must be balanced with the method guidelines at project inception. of maintaining positive building pressurization, • Use periodic peer reviews throughout the conditioning and controls for the interior space, design and construction process to compare ventilation methods, and the effects of energy results against original construction guidelines. management systems.7 • Implement proper startup technique for the HVAC system to verify correct operation of the Appendix C, NIST Personal Computer Model building before it is occupied. 7 (MOIST), describes a computer model developed by the National Institute of Standards and Technology (NIST) for predicting the moisture DESIGN. Regardless of what some design and content of the various construction materials as a building professionals might say, design practices function of time. In this model, the type and and principles are not the same for all parts of the placement of building materials can be varied. It U.S. For example, when design principles that are also can be used to evaluate the effect of various appropriate for a mixed climate are applied to a paints and wallcoverings on moisture accumula- building in a hot, humid climate, the results can be tion. By comparing predicted results with and disastrous. A case in point is the HVAC system. without a vapor barrier, the model can be used to Good design practice dictates providing certain lev- determine whether a vapor retarder is needed els of outside air into occupied spaces based largely and, if so, where it should be placed. In addition, on occupant density and space usage. However, in the model allows users to electronically “move” a hot and humid climates, the highest priority is to wall or ceiling to different U.S. and Canadian maintain proper humidity at all times both during cities to investigate the effect of climate on mois- occupied and unoccupied periods.7 The American ture accumulation. Hourly weather data for six Society of Heating, Refrigerating and Air U.S. cities are provided with the model. Weather Conditioning Engineers (ASHRAE) in its Handbook data for 40 other U.S. and five Canadian cities are Fundamentals cautions that different climates available from ASHRAE.

46 CONSTRUCTION. The critical elements during the the drywall and wallcoverings prior to the building construction phase are sequencing of construc- being dried in, while cement or sprayed on fire tion and quality of assembly. Building materials proofing in other parts of the building are still and components that are susceptible to water curing/drying, and/or before the water piping has and moisture damage must be protected from the been tested. weather during transport to the job site, while waiting installation and after installation. In addi- Also critical is the quality of construction or tion, a preconstruction conference should be held assembly building components. Many quality- between the general contractor, supervisors and related issues can be dealt with through open subcontractors to ensure everyone is clear and to communication through interactive, informed and address any scheduling issues, such as installing cooperative inspections.74

47 Appendix A. List of Guidelines and Resources for Assessment and Remediation of Mold Contamination

Organization Title or Resource Web Site

American Conference of Governmental Bioaersols Assessment and Control www.acgih.org Industrial Hygienists.

American Industrial Hygiene Association Report of the Microbial Growth Taskforce www.aiha.org

American Society of Heating, Refrigerating Standard 62-2001, Ventilation for Acceptable www.ashrae.org and Air-Conditioning Engineers (ASHRAE) Indoor Air Quality ANSI/ASHRAE

California Department of Health Services California Indoor Air Quality Program Information www.cal-iaq.org//iaqsheet.htm Sheets and Links

California Research Bureau Reports Molds, Toxic Molds and Indoor Air Quality www.library.ca.gov/crb/01/notes/v8n1.pdf

Indoor Air Quality in Office Buildings: A Technical www.hc-sc.gcca/ehp/ehd/catalogue/bch_pubs/ Health Canada Guide 93ehd166.htm

Indoor Air Quality Association Mold Resources and Links www.iaqa.com/mold_resources.htm

Indoor Environmental Standards Organization Standards of Practice for the Assessment of Indoor www.iestandards.org Environmental Quality, Volume I: Mold Sampling and Assessment of Mold Contamination

International Society of Indoor Air Quality and Control of Moisture Problems Affecting Biological www.ie.dtu.dk/isiaq Climate Indoor Air Quality. ISIAQ Guideline TFI-1996

International Society of Indoor Air Quality and Guidelines for IAQ in Schools (task force) www.isiaq.org Climate

Minnesota Department of Health Indoor Mold: Health Hazard Identification and www.health.state.mn.us/divs/eh/indoorair/mold/haz Control ardid.html

National Institute of Science and Technology A Computer Analysis of Wall Construction in the http://fire.nist.gov/bfrlpubs/build95/PDF/b95011.pdf Moisture Control Handbook

48 Organization Title or Resource Web Site

New York City Department of Health Guidelines on Assessment and Remediation of nycdoitt.ci.nyc.ny.us/html/doh/ Fungi in Indoor Environments html/epi/moldrpt1.html

Sheet Metal and Air-Conditioning Contractors Duct Cleanliness for New Construction Guidelines www.smacna.org National Association (SMACNA)

University of Minnesota, Department of Fungi in Buildings www.dehs.umn.edu/iaq/fungus/ Environmental Health and Safety Fungal Abatement Safe Operating Procedure www.dehs.umn.edu/iaq/sop.html

Managing Water Infiltration Into Buildings www.dehs.umn.edu/iaq/flood.html

US Centers for Disease Control and Molds in the Environment www.cdc.gov/nceh/airpollution/mold/moldfacts.htm Prevention Questions and Answers About Stachybotrys www.cdc.gov/nceh/airpollution/mold/stachy.htm chartarum and other molds

US Environmental Protection Agency Indoor Air Quality Tools for Schools www.epa.gov/iaq/schools/tools4s2.html

Building Air Quality Handbook www.epa.gov/iaq/iaqinfo.html

Mold Remediation in Schools and Commercial Buildings

Mold Resources www.epa.gov/iaq/pubs/moldresources.html

Washington State Department of Health Got Mold? Frequently Asked Questions www.doh.wa.gov/ehp/ts/IAQ/Got_Mold.html

Is Indoor Mold Contamination a Threat to Health? www.doh.wa.gov/ehp/oehas/mold.html

49 Appendix B. Description of Wallcoverings

Commercial wallcoverings are produced in a wide bable and peelable and can be used in most variety of designs specifically for use in homes, areas of a residence or business as it resists hotels, apartment buildings, office buildings, moisture, stains and grease. It will not with- schools and hospitals. They are manufactured to stand hard physical abuse, however. meet or surpass minimum physical and perform- • Fabric backed vinyl (FBV) (residential and ance characteristics as set forth in federal guide- commercial wallcovering) features a solid vinyl lines such as Federal Specification CCC-W408-D. intermediate layer that is laminated to woven Residential wallcoverings meet or surpass specifi- or non-woven fabric substrate. The vinyl layer cation set forth in ASTM F793. The guidelines can vary from 2 mils to 35 mils in thickness. contain requirements for flammability, tear The woven fabric substrate may be either a strength, abrasion resistance, washability, scrub- scrim fabric with a weight range of 0.75 oz. per bability and stain resistance. Following these sq, yd. up to 1.3 oz. per sq. yd. for Type I or an product descriptions is a chart (Table B-1) that osnaburg fabric with a weight range of 1.75 oz. lists wallcovering product specifications for per sq. yd. to 2.6 oz. per sq. yd. for Type II. both commercial and residential wallcoverings. Non-woven fabric may vary in weight from 1.5 It is a composite of specifications found in the oz. per sq. yd. to 3.0 oz per sq. yd. Lighter CFFA-W-101-D and ASTM F793 documents. weight fabric is typically used for Type I and a higher weight for Type II. Type I (light duty commercial or heavy duty residential) can be VINYL WALLCOVERINGS. Vinyl wallcoverings used in homes, offices, hospital patient rooms consist of one or more layers of vinyl plastic with and hotel rooms, and Type II (medium duty) a polyester, polyester-and-cotton blend woven can be for used in all other areas including foy- fabric, non-woven fabric or paper backing. There ers, lounges, corridors and classrooms. are several categories of vinyl wallcoverings, each Typically, commercial vinyl wallcovering must with specific performance characteristics: meet the specification for wallcovering as stat- • Vinyl coated paper (residential wallcovering) ed in one of the wallcovering specification doc- has a paper substrate on which the decorative uments: Federal Specification Wallcovering, surface has been sprayed or coated with an Vinyl Coated CCC-408 A-D, ASTM Designation acrylic type vinyl or polyvinyl chloride (PVC). F 793-93, Standard Classification of Although more resistant to grease and mois- Wallcovering By Durability Characteristic; or ture than plain paper and suited for residential CFFA-W-101-D, CFFA Quality Standard for kitchens and bathrooms, it does not resist Vinyl Coated Fabric Wallcovering. See the excessive or prolonged exposure to grease, chart following these descriptions for a more moisture or abuse. Thus, it is not suitable for complete breakdown of properties and con- commercial applications. struction of commercial wallcoverings. • Paper backed vinyl/solid sheet vinyl (PBV) • Rigid vinyl sheet (commercial wallcovering) is (residential and commercial wallcovering) has a solid sheet wallcovering that is used in com- a paper (pulp) substrate laminated to a solid mercial applications where there is a potential decorative surface. This type of wallcovering for high-impact damage. This type of wallcov- is very durable as the decorative surface is a ering does not usually have a backing and is solid sheet of vinyl. It is classified as scrub- installed with special contact adhesive.

50 NON-VINYL WALLCOVERINGS. The following meeting rooms, offices, theaters, auditoriums, are examples of wallcoverings that are not made restaurants, corridors and elevator lobbies. with vinyl. All of these wallcoverings can be used They are predominately made of man-made as residential or as commercial wallcovering. polyester and olefin fibers and are tested for • String effects have very fine vertical threads special sound absorption rating known as a laminated to a paper substrate. noise reduction coefficient (NCR) rating. The • Natural textiles are usually laminated to a higher the number, the more noise absorption. backing to enhance dimensional stability and • Cork and cork veneer have variegated texture to prevent the adhesive from coming through with no definite pattern or design. Cork veneer to the surface. These backings are usually is shaved from cork planks or blocks and lami- acrylic or paper. Textiles are constructed of nated to a substrate that may be colored or natural fibers and can be finely designed or plain. coarse, depending on the desired look. • Wood veneer wallcoverings are mostly lami- • Polyolefin/synthetic textiles are woven and nated to fabric backings. Due to environmen- non-woven and were developed to give the tal and grain matching issues, wood veneers aesthetic appearance of a natural textile while are used primarily in offices or conference adding an increased value in stain and abra- rooms and other specialty areas such as large sion resistance. Many are comprised of poly- columns. olefin yarns, which are made from polymers • Underliner is a blank stock-type wallcovering and copolymers of propylene. These products that can be used on almost any wall surface, generally have an acrylic or paper backing. such as plaster, drywall, paneling and cinder • Heavy weight paper and saturated paper may block, to provide a smooth surface for be used in commercial applications. Heavy installing wallcoverings. It comes in light, weight saturated paper may have the same medium or heavy weights, and it can be plain weight and physical strength of some vinyl paper stock or a non-woven material. wallcoverings. Heavy weight paper also may • Fiberglass wallcoverings may have a variety of have the appearance of a heavy weight liner woven appearances. The product is typically paper but the surface can be decorated. installed as a white wallcovering. The surface Products consist of wood pulp and varying is painted to achieve the final desired color. amounts of latex depending on the manufac- Fiberglass wallcoverings are sold in different turer of the product. weight and textures. This product has good • Non-woven wallcoverings are typically made permeability and a natural fire resistance. from cellulose and polyester blends along with latex binders. There is a large variation in weight, decoration, permeability, performance, functionality and composition of various non- Adapted from Introduction to woven products. Non-woven wallcoverings Commercial Wallcoverings, can be used in many of the same areas as residential and commercial wallcoverings. Wallcoverings Association, • Acoustical wallcoverings are used on vertical surfaces, panels, operable walls and any place July 1999. sound reduction is a primary factor such as

51 Table B-1. Wallcovering Characteristics vs. CFFA, ASTM and Federal Specifications

Substrates Natural Kraft, Residential Groundwood, All Bleached Cellulosic Residential and Commercial 19.6-32 Commercial 33-and-up Natural Cork Residential No. 1 Wet Strength Commercial 10-19.5 oz/lin. yd. Calendared oz/lin. yd Calendared Wallcovering Hanging Strippables, Solid Vinyls oz./lin. yd. Calendared or Vinyl on nonwoven or Vinyl on Heavy Osnaburg Stock, Residential Wet (Plastisol Coated Extruded Vinyl on Osnaburg Woven Fabric or Broken Twill Woven Laid Two Ply Peelable Groundwood w/wo a top Sheeting or Nonwoven Fabric Paper, Residential coat), Blown Vinyls on Fabric, Patent Finished Duplex Two Ply Hanging Stock PVC on Woven or Nonwoven Fabric, Metallized PET Laminated to PVC Coated Nonwoven Fabric Category I per Category II per ASTM Category III per ASTM Category IV per ASTM Category V per ASTM Category VI per ASTM ASTM F793 F793 F793 F793 F793 F793

Commercial Type I by CCC-W-408D Type II by CCC-W-408D Type III by CCC-W-408D Classification Type I by CFFA-W-101D Type II by CFFA-W-101D Type III by CFFA-W-101D

Serviceability Decorative only Decorative with medium Decorative with high Decorative with com- Medium commercial High commercial serv- serviceability serviceability mercial serviceability serviceability iceability

Colorfastness (hours) 23 46 200 200 200

Washability (cycles) 100 100 100 100 100

Scrubbability (cycles) 50 200 300 500

Abrasion Resistancy 200 300 1000 (cycles)

Breaking Strength (lbs. of 40 x 30 50 x 55 100 x 95 force) (MD x CMD)

Crock Resistance (cycles) Good Good Good Good

Stain Resistance Good - Reagents 1-9 Good - Reagents 1-9 Good - Reagents 1-12 Good - Reagents 1-12

Tear Resistance (scale 12 x 12 25 x 25 50 x 50 reading) (MD x CMD)

Block Resistance (point 2 2 2 scale)

Coating Adhesion 2 3 3 (lbs. of force per 1” strip)

Cold Cracking Resistance No change No change No change

Heat Aging Resistance Pass Pass Pass

Flame Spread (maximum) 25 25 25 25 25

Smoke Development 50 50 50 50 50 (maximum)

Shrinkage (% maximum) MD Machine Direction 2 2 2

CMD Cross Machine 1 1 1.5 Direction

Mold Resistance by ASTM rating 0 or 1 rating 0 or 1 rating 0 or 1 rating 0 or 1 G21 ASTM F793 Minimum Weight per CFFA 10.5 19.5 33 (oz per linear 54” wide yard)

52 Appendix C. MOIST Personal Computer Model

The body of this publication references a more and time-dependent winter conditions, while their conservative wall surface relative humidity of 70 interior surfaces were maintained at 70 degrees F percent or higher for the onset of mold growth in (21.1 degrees C) and 50 percent relative humidity. the wall cavity.60 The National Institute of These boundary conditions caused moisture from Standards and Technology (NIST), however, has the interior environment to permeate into the wall developed a personal computer model, called specimens and accumulate in their exterior con- MOIST, for predicting the transient moisture and struction materials. Subsequently, when the exte- heat transfer within building envelopes that shows rior air temperature was elevated to 90 degrees F that the onset of mold growth may not begin with- (32.2 degrees C), the exterior construction materi- in the wall cavity until wall surface relative humidi- als lost moisture to the interior environment.75 ty reaches 80 percent.75 A description of the MOIST model and the results of analyses using The moisture content within the exterior construc- MOIST are offered here for interested readers. tion materials and the heat transfer rate at the inside surface of the wall specimens were meas- The computer model permits users to easily ured and compared with MOIST predictions. The define a wall or ceiling and predict the moisture moisture and heat transfer properties for the con- content of the various construction materials as a struction materials comprising the wall specimens function of time. The type and placement of were independently measured and used as input building materials can be varied. By comparing to the MOIST computer model. The agreement predicted results with and without a vapor barrier, between predicted and measured moisture con- the model can be used to determine whether a tents was within 1.1 percent moisture content.76 vapor retarder is needed and, if so, where it should be placed. It also can be used to evaluate For the cooling climate (Southeastern United the effect of various paints and wallcoverings on States), one wall that was tested had risk of mold moisture accumulation. In addition, the model and mildew growth behind an interior vapor allows users to electronically “move” a wall or retarder, which was cooled by the indoor air con- ceiling to different U.S. and Canadian cities to ditioning. During the summer, moisture from the investigate the effect of climate on moisture accu- outdoor environment permeated inwardly through mulation. Hourly weather data for six U.S. cities this construction and accumulated at the interior are provided with the model. Weather data for vapor retarder, and the surface relative humidity forty other U.S. and five Canadian cities are avail- approached and rose above the critical 80 per- able from the American Society of Heating, cent level for mold and mildew growth.75 Refrigerating and Air-Conditioning Engineers in Atlanta, Georgia. The Society’s website is Several of the walls for a cooling climate contained www.ashrae.org.75 an exterior vapor retarder, which decreased moisture transfer to the interior construction layers. The The results of comprehensive laboratory experi- relative humidity behind interior vapor retarders was ments verified the accuracy of the MOIST com- decreased below 80 percent. However, during the puter model in the hygroscopic regime. Three dif- winter, moisture from the indoor environment per- ferent multilayer wall specimens were installed in meated outwardly through the wall construction and a calibrated hot box. The exterior surfaces of the accumulated at exterior vapor retarders where the wall specimens were first exposed to both steady relative humidity rose above 80 percent.75

53 For a cooling climate, the MOIST model was used The results of analysis for walls with vinyl wallcov- to find another good performing wall construction. erings show acceptable performance year-round A permeable wall (without vapor retarding layers for heating and mixed climates. In the humid cli- and low-permeability materials) was found to per- mates during the winter, there is a problem of form satisfactorily. During both winter and sum- condensation if an impermeable membrane or mer periods, moisture passed through the wall non-permeable wallcovering is installed on the construction and did not significantly accumulate interior surface of the exterior walls. Other than in within the construction layers. The analysis pre- hot and humid and fringe climates, the results of sented in this report was limited in that it did not the MOIST computer model of wall construction include moisture transfer by air movement and it demonstrate that non-permeable vinyl wallcover- did not include cyclical rain wetting. Figures C-2 ing show acceptable performance year-round and C-4 illustrate condensation temperature in when used on interior surfaces of exterior walls.13 individual layers of the wall construction.75

13 mm (0.5 in) stucco finish

203 mm (8 in) masonry block

25 mm (1 in) extruded polystyrene 25 mm (1 in) air space 13 mm (0.5 in) gypsumboard with vinyl wallpaper

Figure C-1. A non-permeable wall in Figure C-2. Relative humidity at layer a cooling climate. surfaces versus time of year for Figure C-1 of cooling climate (indoor relative humidity of 50 percent).

54 Figure C-3. A permeable wall for Figure C-4. Computer simulation of permeable cooling climate. wall construction for a cooling climate.

55 Appendix D. Standard Test Method and Calculation of Permeability as Prescribed in ASTM E 96-95, Standard Test Methods for Water Vapor Transmission of Materials*

This test measures the transmission of water of a body, normal to specific parallel surfaces, vapor through samples of materials less than under specified temperature and humidity con- 1 1/4 in thick. The test can be run in two very ditions at each surface. different configurations that help to characterize the sample in distinctly different environments. Sample Limitation and In one method, Wet Cup, water is placed in the Characterization cup and water vapor lost through the membrane is measured. The other method, Dry Cup, has a • Sample components that react with water, desiccant placed in the cup that pulls moisture such as water-activated prepaste, must be from any water vapor that passes through the eliminated before testing. membrane. Because of the different driving • Embossed samples must be measured for force, values measured by different methods are thickness in the center of the exposure area to not expected to agree or to correlate. The test the nearest 1/1,000 inch. method selected for the measurement should be • Embossed samples overall thickness shall be selected as closest to the conditions the material at least five times the sum of the maximum pit is expected to experience in field service. depth and its tested permeance shall not be greater than 5 perms. Definition of Terms • Because time to reach equilibrium varies as the square of the thickness, thicker products will • Water vapor permeability – the time rate of be tested until they reach a constant rate that water vapor transmission through a unit area may take 60 days. of flat of unit thickness induced by a unit vapor pressure difference between two specific surfaces, under specified temperature and humidi- Calculation ty conditions. • Water vapor permeance – the time rate of By weighing the sample and plotting the loss water vapor transmission through a unit area of the moisture vapor transmission rate (mvt) can flat material or construction induced by a unit be determined by drawing a straight line with vapor pressure difference between two specific at least six point and determining the line’s surfaces, under specified temperature and slop as the sample’s mvt. This evaluation humidity conditions. requires experience to draw the correct line • Water vapor transmission rate – the steady and is best conducted by laboratory people water vapor flow in unit time through unit area who routinely run this test.

The test can be run in two very different

configurations — dry cup or wet cup —

that can help characterize the sample in

distinctly different environments.

56 Water Vapor Transmission Example – In a desiccant test that ran 288 hours WVT = G/tA = (G/t)/A (12 days) on an exposed area of 100 in.2 (0.0645 m2), it was found that the rate of gain was sub- Where: stantially constant after 48 h and during the sub- sequent 240 h, the weight gain was 12 g. The In inch-pound units: controlled chamber conditions were measured at 89.0 degrees F (31.7 degrees C) and 49 percent G = weight change, grains (from the straight line) relative humidity. t = time during which G occurred, h G/t = slope of the straight line, grains/h Required: WVT and permeance A = test area (cup mouth area), ft2 2 WVT = rate of water vapor transmission, grains/h·ft Calculation (inch-pound units): 15.43 grains In metric units: G/t = 12 g x g ÷ 240 h = 0.771 grains/h G = weight change (from the straight line), g t = time, h, A = 100 in.2 x 1 ft2 = 0.695 ft2, G/t = slope of the straight line, g/h, 144 in.2 A = test area (cup mouth area), m2, and S = 1.378 in. Hg (from standard references tables), WVT = rate of water vapor transmission, g/h·m2 R1 = 49% (in chamber)

Permeance R2 = 0% (vapor sink), and Permeance = WVT/∆p = WVT/S(R -R ) 1 2 WVT = 0.771 grains/h ÷ 0.694 ft2 = 1.11 grains/ft2 h.

∆ Where: Permeance = WVT/ P = WVT/S (R1 – R2)

= 1.11 grains/ft2 h ÷ 1.378 in. Hg (0.49 – 0) In inch-pound units: ∆p = vapor pressure difference, in. Hg = 1.64 grains/ft2 h in. Hg = 1.64 perms S = saturation vapor pressure at test temperature, in. Hg. Calculation (metric units): R1 = relative humidity at the source expressed G/t = 12 g/240 h = 0.05 g/h, as a fraction (the test chamber for desic 2 cant method; in the dish for water A = 0.0645 m , method), and S = 35 mm Hg (from reference tables), R2 = relative humidity at the vapor sink expressed as a fraction = 35 mm Hg x 1.333 x 102 Pa/mm Hg = 46.66 x 102 Pa,

In metric units: R1 = 49% (in chamber), ∆ p = vapor pressure difference, R = 0% (vapor sink), and mm Hg (1.333 X 102 Pa) 2 S = saturation vapor pressure at test WVT = 0.05 g/h ÷ 0.0645 m2 = 0.775 g/h . m2 temperature, mm Hg (1.333 X 102 Pa) ∆ R1 = relative humidity at the source expressed Permeance = WVT/ P – WVT/S (R1 – R2) as a fraction (the test chamber for desic cant method; in the dish for water = 0.775 g/h m2 x 1 h/3600s ÷ 46.66 x 102 Pa x (0.49 – 0) method) = 9.42 x 10-8 g/Pa . s . m2 R2 = relative humidity at the vapor sink expressed as a fraction

* “Adapted, with permission, from E 96-95 - Standard Test Methods for Water Vapor Transmission of Materials”, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be obtained from the ASTM, phone: 610-832-9585, fax: 610-832-9555, e-mail: [email protected], website: www.astm.org . 57 Appendix E. Frequently Asked Questions

What are mold and mildew and where are they a person or animal passing by, or actively dis- found? charged by the mold, usually under moist conditions or high humidity. Although they are always microscopic, spores contain one to many cells Mold and mildew are generic terms that are used and differ greatly in size, shape, color and method to describe essentially the same fungi, with mold of formation. Mold spores can survive for many used to describe fungi growing on surfaces and years in dry or hot environments, requiring only mildew to describe fungi growing on fabrics. moisture, the right temperature and an available Mold is EVERYWHERE, both in the indoor and food source in order to start growing. See outdoor environments. Many species of mold are Section 1.4, Mold, Mildew, Fungi – What’s the essential to every day life and are beneficial to Difference, for more information. health, although there are a few species that can be destructive to building materials and may cause some adverse health effects. See Section What are mycotoxins? 1.4, Mold, Mildew, Fungi – What’s the Difference; Section. 1.5, Different Types of Indoor Mold; and Some species of mold produce substances called Section 1.6, Are Molds Really Toxic?, for more mycotoxins, some of which may be poisonous to information. humans and animals. Mycotoxin production for a given species depends a lot on growth condi- How can I be exposed to mold and mildew? tions, such the availability of food, the right temperature and enough moisture. There is a great Everyone is exposed to mold and mildew every- deal of information about the effects of ingesting day, as they are EVERYWHERE, both in the indoor certain mycotoxins in humans and animals, but and outdoor environments. When a moldy materi- investigators have only just begun to study health al becomes damaged or disturbed, spores and implications of inhaling these substances. See parts of the mold colony called, hyphae, can be Section 1.6, Are Molds Really Toxic?, for more released into the air. Exposure can occur if air- information. borne spores are inhaled. Exposure also can occur if moldy materials are directly handled with- What does permeability mean? out proper protection. See Section 1.4, Mold, Mildew, Fungi – What’s the Difference, and Permeability is a measure of the amount of air or Section 3.2, Specific Personal Protection and water vapor that can pass through a membrane in Containment Guidelines, for more information. a certain amount time. It is usually measured in the number of grams that can pass through a What are mold spores? membrane in a 24-hour period. Because residential wallcoverings do not need to be as strong or Mold spores are like seeds. When they germinate durable as commercial wallcoverings, their struc- they form hyphae, which is the primary compo- ture tends to be more permeable than commercial nent of a mold colony. Spore and hyphae can wallcoverings. At this time, however, there are no break free from the colony and travel to another standard industry permeability ratings for wallcov- area and start a new colony. Spores may travel in erings and many product labels do not contain several ways, including being passively moved by ratings of this sort. This publication provides esti- a breeze or water drop, mechanically disturbed by mates of permeability ratings for wallcovering

58 materials. These values, along with the discus- Mold, Mildew, Fungi – What’s the Difference, for sion in Section 1.3, Wallcoverings and Mold: A more information. Function of Moisture Levels and Permeability, offer a helpful comparison with other building I removed some wallcovering in August and my materials. walls were damp. I removed additional wallcovering in January and the walls were dry. I had How can I get rid of mold or mildew in a home about the same amount of mold in both places. or building? What is going on?

The most effective solution is to eliminate all During the summer (cooling season), condensa- sources of unwanted moisture within the home or tion can occur on the backside of wall, which building. There are primarily four sources of causes the wallboard to be damp. During the moisture, including: building tightness, which winter (heating season), the wallboard tends to does not allow moisture to escape to the out- dry out as condensation (if any) may occur on the doors; liquid water infiltration from outside as a interior side of the building envelope rather than result of a leaky building envelope or structural the backside of the wall itself. The temptation is failure; moisture condensation on cold surfaces, to assume that moisture intrusion is no longer a which originates from water vapor inside or out- problem and all that needs to be done is to clean side the building; and moisture generated within up any visible mold. Do not be fooled! Evidence the building by the occupant and the occupant’s of mold is sufficient proof that at some point dur- activity such as operating showers without bath- ing the year there is enough moisture in the wall room ventilation to the exterior, cooking without cavity for a long enough period of time to support ventilation of steam to the exterior and drying mold growth. The source of that moisture must clothes without venting the unit to the exterior. be found and corrected in order for any remedia- See Section 1.2, Overview of Mold in Building and tion efforts to be successful. See Section 1.2, Home Interiors, and Section 4.1, Eliminate Overview of Mold in Building and Home Interiors, Sources of Moisture, for more information. and Section 4.1, Eliminate Sources of Moisture, for more information. My home or office has a musty odor, but I do not see any signs of mold or mildew on the walls. If I bleach the walls after removing the wallcover- Where does the odor come from? ing, have I killed all of the mold?

The odors are a byproduct of mold and mildew If mold was present when the wallcovering was growth. Mold or mildew may be growing under- removed and even though the wall was thorough- neath the wallcovering or inside the wall cavity ly cleaned, if no effort was made to correct any where you cannot see it. The odor may be enter- moisture problems then the mold will probably ing the room through the electrical outlets. Mold return. Any moisture problem should be correct- also may be growing in the HVAC system or in a ed before replacing the wallcovering. See Section nearby area that is using the same HVAC system, 3.1, Cleaning, Removing Building Materials; with the odors entering the room through the air Section 3.3, Verifying Successful Remediation; ducts. See Section 1.2, Overview of Mold in and Section 4.1, Eliminate Sources of Moisture, Building and Home Interiors, and Section 1.4, for more information.

59 I found mold on a sidewall rather than an exterior How do breathable wallcoverings keep my wall wall. The moldy area was approximately 5 feet from growing mold? from the floor and 1 foot from the ceiling and about 4 feet from the sides of the wall. How can Breathable (or permeable) wallcoverings allow mold grow in the center of the wall without a moisture to pass through the wallcovering surface water leak of some type? or membrane. The HVAC system then removes the moisture from the air. As a result, insufficient Likely, the HVAC system is blowing cool air onto a moisture is present in the wall to allow mold to sidewall causing localized cooling of the wall sur- grow. Because residential wallcoverings do not face. Moisture from the warm moist air in the wall need to be as strong or durable as commercial cavity will condense on the cooled wall surface wallcoverings, their structure tends to be more much like water droplets forming on a glass of ice permeable than commercial wallcoverings. See water. The condensation can eventually saturate Section 1.2, Overview of Mold in Building and the wallboard, providing enough moisture for Home Interiors, and Section 1.3, Wallcoverings mold to grow. See Section 1.2, Overview of and Mold: A Function of Moisture Levels and Mold in Building and Home Interiors, for more Permeability, for more information. information. How can I tell whether a wallcovering is breathable (permeable) or not? I have a large area of wallcovering with mildew. What should I do? Most wallcovering products do not contain permeability ratings on their labels. Contact your If the area is larger than 10 sq. ft., contact an supplier or distributor to find out the permeability expert who can assess the problem, determine rating of a specific product. For more informa- the source of moisture and recommend steps tion, see Section 1.3, Wallcoverings and Mold: to eliminate the moisture and clean up the A Function of Moisture and Permeability. mold. Areas smaller than 10 sq. ft. can be cleaned or removed without the help of an Can I blow air through a breathable (permeable) expert. In any case, the source of the moisture wallcovering? must be found and fixed in order for any remediation effort to be successful. See all of High permeable wallcoverings such as textiles will Section 2, How to Tell If a Mold Problem Exists, readily allow air to pass. Low permeable wallcover- for more information. Also, Appendix A, List of ings, however such as perforated vinyl wallcovering, Guidelines and Resources for Assessment and paper or non-woven wallcoverings will allow water Remediation of Fungal Contamination, features vapor or moisture to pass but air movement will not a list of additional resources for information be readily noticeable. See Section 1.3, about mold, assessment, remediation and Wallcoverings and Mold: A Function of Moisture removal. Levels and Permeability, for more information.

60 Should I use breathable (permeable) wallcovering A Function of Moisture Levels and Permeability, in a kitchen, bath or sauna area? for more information about perforating or microventing wallcoverings, especially as these Since the warm, moist air from the kitchen, bath techniques relate to permeability. or sauna could penetrate the breathable (permeable) wallcoverings, non-breathable (impermeable) If I hang a non-breathable (or impermeable) wall- wallcoverings such as vinyl would be a better covering over an existing mildewed wallcovering, choice in the bath/sauna area. See Section 1.3, will the first layer of wallcovering keep the top Wallcoverings and Mold: A Function of Moisture layer of wallcovering from mildewing and chang- Levels and Permeability, for more information. ing colors?

What if I just cut a hole in my wall to let the warm, The color changes in the first layer will eventually moist air out of the wall cavity? Wouldn’t that dry occur with the second layer as well. Also, the my wall out? first layer may become loose and delaminate from the wall as a result of the increased weight and Putting a hole in the wall would allow more moist air the continued mold growth under the first layer. into the room and it also would increase the airflow Installing wallcovering over existing wallcovering and condensation on the back of the drywall. In also will increase the flame, smoke and toxicity of other words, it would make matters a lot worse. the flame in the event of a fire. In short, it is not Finding and eliminating the source of moisture is at all a good idea. See Section 3.1, Cleaning, vitally important for preventing mold growth. See Removing Building Materials, for more Section 1.2, Overview of Mold in Building and Home information. Interiors, and Section 4.1, Eliminate Sources of Moisture, for more information. I had a severe mold problem caused by a leaky roof. I installed perforated wallcovering, but the Does perforation affect the fire rating for mildew returned. What happened? wallcovering? Breathable (or permeable) wallcoverings such as No, fire ratings are the same as non-perforated perforated or “microvented” wallcoverings may wallcoverings. This publication does not specifi- not be able to overcome the amount of water cally address fire ratings. leaking from the roof. In order to prevent mold from returning, the source of the leaks must be Does perforation affect the physical values of identified and fixed. Water leaks provide moisture wallcovering? needed for mold growth and building deterioration regardless of whether wallcoverings are present Perforating or microventing woven backed wall- or not or what type of wallcoverings are used. coverings does not change their physical charac- See Section 1.2, Overview of Mold in Building and teristics. Perforating or microventing non-woven Home Interiors; Section 3.1, Cleaning, Removing backed wallcoverings, however, will weaken them. Building Materials; and Section 4.1, Eliminate See Section 1.3, Wallcoverings and Mold: Sources of Moisture, for more information.

61 What is a positively pressurized home or building, mold can grow. The area would tend to be localized and what is the advantage of having a positively to the leaky area and typically not wide spread over pressurized home or building? an entire building as it would be in a negatively pressured building, although water can travel along When a home or building is positively pressurized, pipes and duct work to other areas of the building. the air pressure inside is at a slightly higher pres- See Section 1.2, Overview of Mold in Building and sure than outside the structure. The advantage is Home Interiors, and Section 4.1, Eliminate Sources cool, dry air inside the home or building pushes its of Moisture, for more information. way into cracks and crevices and into air cavities or inside wall cavities in the building. The cool, dry How dry does the air in a home or building need inside air also does not condense inside the wall to be and can people live comfortably in a posi- cavities and any infiltration of warm, moist air from tively pressurized home or building? outside would be stopped. Other sources of water A home or building maintained at about 50 per- or moisture from structural or plumbing leaks will cent humidity and 72 degrees F will be comfort- not be affected. As a result, these sources of mois- able for most people. At a relative humidity of 60 ture must be independently corrected. See Section percent or higher, mold will grow. A positively 1.2, Overview of Mold in Building and Home pressurized building will usually go unnoticed Interiors, and Section 4.1, Eliminate Sources of except when entering the home or building. Moisture, for more information. The air would flow out instead of into the entrance. Proper maintenance of the HVAC sys- Can mildew grow within a positively pressurized tem will provide comfortable surrounding indoor building? environment in which to live or work. See Section 1.2, Overview of Mold in Building and Home If sufficient moisture from a roof leak, pipe leak or Interiors, and Section 4.1, Eliminate Sources of any other moisture source builds up in an area then Moisture, for more information.

62 Appendix F. Glossary

Allergen – A substance that elicits an allergic Ethanol – A compound produced by mold as a reaction. Fungal allergens are proteins found in metabolic byproduct, which is often useful for either the mycelium or spores. Only a few fungal determining if there is active mold growth. allergens have been characterized, but all fungi are thought to be potentially allergenic. Ergosterol – A compound produced by mold as a metabolic byproduct, which is often useful for Allergenic – Able to produce an allergic reaction. determining if there is active mold growth.

Biocides (also known as Fungicides) – Chemicals Fascia – A vertical wood member, such as a that limit the growth or kill microorganisms such cedar, 1 in. by 6 in., nailed to the ends of the as fungi. rafters. It is often the backing of the gutter.

Black Mold (also known as Toxic Black Mold or Flashing – A building component used at the Toxic Mold) – A poorly defined term that usually interface of portions of a roof, deck, or siding has been associated with the species of mold material to another surface such as a chimney, known as Stachybotrys chartarum. While there wall or vent pipe. It is often made of various are only a few mold species that are truly black, metals, rubber or tar and is mostly intended to there are many that can appear black. Not all prevent water from entering a building or home. molds that appear black are Stachybotrys. Fungi – Naturally occurring organisms that make Building envelope (also known as Exterior up approximately 25 percent of the earth’s bio- Envelope) – The part of the building that consists mass and play an essential role in the processing of all of the elements protecting the interior from of decaying organic matter into substances that the outside weather elements, including roofing, are necessary for sustaining plant and animal life. siding, windows, exterior doors, porches, flashing Approximately 69,000 species of fungi have been trim, caulking, waterproof decking, venting sys- described in the scientific literature and estimates tems, chimneys and other elements which relate for the total number exceed 1.5 million. to the exterior surfaces of the structure. Hidden Mold – Mold growth on building compo- Colony – An organized area of mold growth. nents and materials that is not easily seen, including the areas above drop ceilings, within a wall Drywall (also known as Gypsum Wallboard, cavity (the space between the inner and outer Sheetrock™ or Plasterboard) – A wall component structure of a wall), inside air handlers or within consisting of a manufactured panel made out of the ducting of an HVAC system. gypsum plaster and encased in a thin cardboard or paper. It is usually 1/2 to 3/4 inches thick and 4 ft. Hypersensitivity – Great or excessive sensitivity. by 8 ft., 4 ft. by 9 ft. or 4 ft. by 12 ft. in size. The panels are nailed or screwed onto the framing and the Hypha (plural Hyphae) – An individual fungal joints are taped and covered with a joint compound. thread or tubular filament of connected cells, Green board type drywall has a greater resistance to which represent the individual parts of the fungal moisture than regular (white) plasterboard. body. Appears as a branching structure with cell

63 walls. Mold spores germinate to produce hyphae, humans and animals, but investigators have only which grow and branch within or on the surface just begun to study health implications of inhaling on which they are growing. They typically pro- these substances. duce a colony that eventually forms a new generation of spores. Mold also can spread if a frag- Mycology – The study of fungi. ment of broken hyphae is transplanted to an area that has adequate moisture, warm enough tem- Nonsporulating – Fungal colonies that do not pro- peratures and a nutrient source. duce spores.

Immunocompromised – Individuals whose Opportunistic Pathogen – Any organism capable immune systems are weakened and susceptible of causing disease only in a person whose resist- to opportunistic diseases or infections. People ance is lowered. Fungi occasionally act as who are classified as immunocompromised pathogens when conditions unusually favorable include but not limited to those with AIDS , cer- for infection arise; for example, in people who tain cancers, the very old, the very young or those have AIDS, certain cancers, the very old, the very undergoing immunosuppressive drug therapy. young or those undergoing immunosuppressive drug therapy. Microbial Volatile Organic compounds (MVOCs) – Chemicals fungi produce as a result of their Oriented Strand Board (OSB) (also known as Chip metabolism. Some MVOCs are responsible for Board or Wafer Board) – A manufactured wood the characteristic moldy, musty or earthy smell of panel composed of 1- and 2-inch wood chips and fungi. Exposure to high levels of VOCs, from any glue. It is often incorrectly used as a substitute source – not just mold – can irritate mucous mem- for plywood. branes and cause headaches, attention deficiencies, inability to concentrate and dizziness. Pathogen – An organism that causes disease.

Mold and Mildew – Generic terms used to Remediate (or Remediation) – Simply means to fix describe essentially the same types of fungi, with a problem. As it relates to mold, remediation mold used to describe fungi growing on surfaces includes fixing the water/moisture problem and and mildew to describe fungi growing on fabrics. the cleaning, removal and/or replacement of damaged or contaminated building materials. Mycelium – A mass of hyphae making up a colony of fungi. Saprobes – Organisms that use non-living organic materials to grow and reproduce. Mycotoxin – Chemical compounds produced by some fungi, some of which may be toxic to Sensitization – Repeated or single exposure to an humans or animals. By convention, the term allergen that results in the exposed person “mycotoxin” excludes mushroom toxins. Fungi becoming hypersensitive to the allergen. that produce mycotoxins are called “toxigenic fungi”. There is a great deal of information about Sheathing – The plywood, board, OSB or other the effects of ingesting certain mycotoxins in material used as the base for the roofing.

64 Soffit – A small ceiling-like space, often out of news media and is used most often in reference doors, such as the underside of a roof overhang. to Stachybotrys chartarum and the alleged severe health effects associated with exposure to this Spore – General term for a reproductive structure in type of mold. fungi, bacteria and some plants. Mold spores can survive for many years in dry or hot environments, Toxigenic Fungi – Fungi that can produce requiring only moisture, the right temperature and mycotoxins. an available food source in order to start growing. Spores may travel in several ways, including being Treated Lumber – A wood product impregnated passively moved by a breeze or water drop, with chemicals to reduce damage from wood rot mechanically disturbed by a person or animal pass- or insects. Often used for the portions of a struc- ing by, or actively discharged by the mold, usually ture likely to be in ongoing contact with soil and under moist conditions or high humidity. water such as a deck. Wood may also be treated with a fire retardant. Sporulating – Fungal colonies that produce spores. Visible Mold – Mold growth that can be easily seen. “Toxic” Mold – A term that has no scientific meaning, as mold itself is not toxic. The metabolic Water Activity (aw) – A measure of water within a byproducts of some molds may be toxic, however building material or component that an organism (see mycotoxin). The term was coined by the can use to support growth.

Adapted from the American Industrial Hygiene Association’s

The Facts About Mold: A Glossary, which can be viewed at

http://www.aiha.org/GovernmentAffairs-PR/html/mold-glossary.htm,

and Start Remodeling.com glossary, which may be viewed at

http://www.startremodeling.com/construction_glossary.htm. Also,

Stedman’s Medical Dictionary, 27th edition. Lippincott, Williams & Wilkins.

Philadelphia, Pennsylvania. 2000.

65 References

1. Boelens T. Introduction. IN: Mold & Mildew in Hotel and Refrigerating and Air-Conditioning Engineers, Inc. Atlanta, Motel Guestrooms in Hot and Humid Climates. John P.S. Georgia. 2001. Salmen and James A. Diluigi, eds. The Hospitality Lodging 13. DeProspero D. Director of purchasing, Imperial Home & Travel Research Foundation. Washington, DC. 1991. Decor Group. Cleveland, Ohio. Personal communication. 2. Majority of Americans concerned about the impact of IAQ January 14, 2003. on health. Press release. Chelsea Group, Ltd. Itasca, 14. Aulbach R. Existing hotels and motels. IN: Mold & Illinois. May 1, 2001. Mildew in Hotel and Motel Guestrooms in Hot and Humid 3. Sullivan Marketing Report 2000. IN: The Commercial Climates. John P.S. Salmen and James A. Diluigi, eds. Wallcovering Information Base. Sullivan Marketing The Hospitality Lodging & Travel Research Foundation. Group. Malvern, Pennsylvania, 2000. Washington, DC. 1991.

4. Control of moisture problems affecting biological indoor 15. Introduction to Commercial Wallcoverings. Wallcoverings air quality, ISIAQ guideline TFI-1996. International Society Association, July 1999. of indoor Air Quality and Climate, Ontario, Canada. 1996 16. Condensation Control of Exterior Walls of Manufactured 5. Lstiburek J, Carmody J. Introduction. IN: Moisture Homes Sited in Humid and Fringe Climates; Waiver, Final Control Handbook: Principles and Practices for Rule. US Department of Housing and Urban Residential and Small Commercial Buildings. Van Development. Part IV. Federal Register. 24 CFR Part 3280. Nostrand Reinhold, New York, New York. 1993. (67) 29: 20400-20403. April 24, 2002.

6. Energy Information Administration. 1999 Commercial 17. Vinyl by design – vinyl wallcovering. Posted on the Buildings Energy Consumption Survey. U.S. Department Wallcoverings Association website: www.vinylbydesign- of Energy. Posted at www.eia.doe.gov/emeu/cbecs/- .com/wallcovering/index.html. Chicago, Illinois. Visited char99/prelim1.htm. Accessed January 7, 2002. October 7, 2002.

7. Odom JD, DuBose G. Preventing Indoor Air Quality 18. Downs P. Vinyl and mildew: moisture is the culprit, not the Problems in Hot, Humid Climates: Problem Avoidance contractor. Virtual Paintstore: The Online News Source for Guidelines. CH2M Hill. Orlando, Florida. 1996. Painting & Wallcovering Contractors. PWC Magazine. http://www.paintstore.com/archives/mildew/viny0895.html. 8. Lstiburek J. Moisture, building enclosures and mold, part Finan Publishing. St. Louis, Missouri. Visited October 7, 1 of 2. HPAC Engineering, December 2001. p. 22-26. 2002. 9. Bissett J. Fungi associated with urea-formaldehyde foam 19. Lstiburek J. Understanding the terms barrier and retarder insulation in Canada. Mycopatholgia. 99:47-56. 1987. As for vapor and air. Posted at www.buildingsciences.com. reported in Control of moisture problems affecting biolog- February 2002. Visited November 7, 2002. ical indoor air quality. ISIAQ Guideline TFI-1996. International Society of Indoor Air Quality and Climate. 20. McNeel SV, Kreutzer, RA. Fungi & indoor air quality. Ottawa, Ontario, Canada. 1996. Health & Environment Digest. 10(2): 9-12. May/June 1996.

10. Burge HA. The fungi: how they grow and their effects on 21. Yeast information for the nonspecialist. World Wide Web human health. HPAC Heating, Piping, Air Conditioning. Virtual Library. Gerard Manning central catalog pages (69)7: 69-74. July 1997. manager. http://genome-www.stanford.edu/Sacch- aromyces/VL-yeast.html#other. Home page of WWW 11. Mold & Mildew in Hotel and Motel Guestrooms in Hot and Virtual Library www.vlib.org. Visited December 12, 2002. Humid Climates. John P.S. Salmen and James A. Diluigi, 22. Lovatt C. Fungi and cheese-making. Visit to Hartington eds. The Hospitality Lodging & Travel Research Cheese Factory, February 1999. Northwest Fungus Group Foundation. Washington, DC. 1991. (affiliated with the British Mycological Society.) http://fun- 12. Hens HLSC. Mold in dwellings – a building physics relat- gus.orguk/nwfg/lovaug00.htm. 2000. Visited December ed approach. In: Proceedings of Indoor Air Quality 12, 2002. 2001Conference. American Society of Heating,

66 23. Churchill A. Fungi uses as a resource for therapeutic 34. Flannigan B, McCabe EM, McGarry F. Allergenic and toxi- agents. American Medical Association Briefing on Food genic micro-organisms in houses. Journal of Applied Biotechnology. October 4, 2001. Bacteriology Symposium Supplement. 70:61S-73S. 1991. As reported in McNeel and Kruetzer 1996. 24. Robbins CA, Swenson LJ, Nealley ML, et al. Health effects of mycotoxins in indoor air: a critical review. 35. US Environmental Protection Agency, Indoor Environment Applied Occupational and Environmental Hygiene. 15(10) Management Branch. Children’s Health Initiative: Toxic 773-784. 2000. Mold. Posted at www.epa.gov/appcdwww/crb/iemb/- child.htm. As reported in Davis 2001. 25. Levetin E. Fungi IN: Bioaerosols. Harriet A. Burge, ed. Center for Indoor Air Research. Lewis Publishers. CRC 36. Ciegler A, Bennett, JW. Mycotoxins and mycotoxicoses. Press, Inc. Boca Raton, Florida. 1995. BioScience. 30:512-515 (1980) as reported in Gotts RE. Mold and mold to xins: the newest toxic tort. Journal of 26. Davis PJ. Molds, toxic molds, and indoor air quality. Controversial Medical Claims. 8(1) 1-3. February 2001. California Research Bureau, California State Library, Sacramento, California. 2001. 37. D’Mello, JP. Handbook of Plant and Fungal Toxicants, CRC Press, Boca Raton, Florida. 1990. As reported in 27. University of Minnesota Department of Environmental Gotts 2001. Health & Safety. Fungal Glossary. 2001. Posted at www.dehs.umn.edu/iaq/fungus/glossary.html. Visited 38. Gotts RE. Mold and mold toxins: the newest toxic tort. January 8, 2002. Journal of Controversial Medical Claims. 8(1) 1-3. February 2001. 28. Shelton BG, Kirkland KH, Flanders WD et al. Profiles of airborne fungi in buildings and outdoor environments in 39. Daisey J and Angell A. A Survey and Critical Review of the United States. AEM: (68) 4: 1743-1753. April 2002. the Literature on Indoor Air Quality, Ventilation and Health Symptoms in Schools. LBNL-41517. Berkeley, California: 29. Adverse human health effects associated with molds in Lawrence Berkeley National Laboratory. March 1998. As the indoor environment. ACOEM Evidence-based reported in Davis 2001. Statement. October 27, 2002. American College of Occupational and Environmental Medicine. Arlington 40. Montz, WE. Fungal contamination and abatement proce- Heights, Illinois. 2002. dures. INvironment® Professional. (7)3: 4-6. March 2001.

30. Ammann HM. Is indoor mold contamination a threat to 41. Burge HA. Bioaerosol investigations. IN: Bioaersols health? Washington State Department of Health. Posted Assessment and Control. Janet Macher, ed. American at www.doh.wa.gov/ehp/oehas/mold.html. Visited Conference of Governmental Industrial Hygienists. January 8, 2002. Cincinnati, Ohio. 1999.

31. Guidelines on Assessment and Remediation of Fungi in 42. Morey PR. Comparison of airborne culturable fungi in Indoor Environments. New York City Department of moldy and non-moldy buildings. Paper 2-524 IN: Indoor Health, Bureau of Environmental & Occupational Air 99 Proceedings of the 8th International Conference on Disease Epidemiology. New York, New York. Indoor Air Quality and Climate. Construction Research April 2000. Communications, Ltd. London, England. 1999.

32. Burge HA, Otten JA. Fungi. IN: Bioaersols Assessment 43. Burge HA. The fungi. IN: Indoor Air Quality Handbook. and Control. Janet Macher, ed. American Conference of John D. Spengler, Jonathan M. Samet, John F. McCarthy Governmental Industrial Hygienists. Cincinnati, Ohio. eds. McGraw Hill. New York, New York. 2000. 1999. 44. Herriman LG, Brundrett, GW, Kittler R. Chapter 7. Mold 33. Richerson H. Unifying concepts underlying the effects of and Mildew.IN: Humidity Control Design Guide for organic dust exposure. American Journal of Industrial Commercial and Institutional Buildings. American Society Medicine. 17: 139-142. 1990. As reported in McNeel and of Heating, Refrigerating and Air-Conditioning Engineers, Kruetzer 1996. Inc. Atlanta, Georgia. 2002.

67 45. Fallon S. Moisture meters help detect, locate, measure 54. Morey PR. Bioaerosols in the indoor environment: current water in building materials. Indoor Environment practices and approaches. IN: Practitioner’s Approach to Connections (3) 12. October 2002. Indoor Air Quality Investigations. Donald M. Weekes and www.ieconnections.com. Visited October 8, 2002. Richard B. Gammage eds. The American Industrial Hygienists Association. Fairfax, Virginia. 1990. 46. Delmhorst Instrument Co. Indoor Air Quality and Remediation: Using a Moisture Meter for Water 55. Shaughnessy RJ, Morey PR. Remediation of microbial Damage Applications FAQ. Delmhorst Equipment Co. contamination. IN: Bioaerosols Assessment and Control. Posted at www.delmhorst.com. Towaco, Janet Macher, ed. American Conference of Governmental New Jersey. Visited January 11, 2002 and December Industrial Hygienists. Cincinnati, Ohio. 1999. 10, 2002. 56. Jackson D. OMNOVA Solutions. Inc. Personal 47. Pasanen AL, Rautila S, Kasanen J-P et al. The relation- Communication. December 10, 2002. ship between measured moisture conditions and fungal 57. Cole EC, Foarde KK. Biocides and antimicrobial agents. concentrations in water-damaged building materials. IN: Bioaersols Assessment and Control. Janet Macher, Indoor Air 2000 (10) 111-120. 2000. ed. American Conference of Governmental Industrial Hygi 48. Odom JD, Scott R. The escalating risks from moisture enists. Cincinnati, Ohio. 1999. and mold problems. ABC Today. (11)10: 11. October 2002. 58. Benda G. Chelsea Group perspective. INvironment® 49. Pratt AJ, Tiffany A, Bader HA. Detection of Stachybotrys Professional (7)12: 5. December 2001. chartarum by culturable air samples. Paper 4-903 IN: 59. Ansari O, Morey PR. Cleaning to remove Aspergillus ver- Indoor Air 99 Proceedings of the 8th International sicolor from a mold-contaminated building. IN: IAQ ’96 Conference on Indoor Air Quality and Climate. Paths to Better Building Environments. American Society Construction Research Communications, Ltd. London, of Heating, Refrigerating and Air-Conditioning Engineers. England. 1999. Atlanta, GA ,1996. As reported in: Shaughnessy RJ, 50. Pasanen AL, Yli-Pietila, Pasanen P et al. Ergosterol Morey PR, 1999. Content as a Tracer of Fungal Contamination in Building 60. Rautiala S, Reponen T, Hyvarinen A et al. Exposure to air- Materials. Paper No. 4-886 IN: Indoor Air 99 Proceedings borne microbes during the repairs of moldy buildings. of the 8th International Conference on Indoor Air Quality Am. Ind. Hyg. Assoc. J. 57:279-284. 1996. As reported in: and Climate. Construction Research Communications, Shaughnessy RJ, Morey PR, 1999. Ltd. London, England. 1999. 61. Weber AM, Martinez, KF. NIOSH health hazard evaluation 51. Miller RV. Evolving PCR-based technologies for report 93-110-2575. Martin County courthouse and con- bioaerosol detection and quantification. INvironment® stitutional office building, Stuart, Florida. May 1996. U.S. Professional. (7)10: 4-6. October 2001. Department of Health and Human Services. 1996. As 52. Land CJ, Must A. Detection and identification of reported in: Shaughnessy RJ, Morey PR, 1999. Stachybotrys chartarum from damp gypsum boards by 62. Hens, HLSC. Fungal defacement in buildings: a perform- the polymerase chain reaction (PCR). Paper 4-939 IN: ance-related approach. HVAC&R Research. 5(3) 265-280. Indoor Air 99 Proceedings of the 8th International July 1999. Conference on Indoor Air Quality and Climate. Construction Research Communications, Ltd. London, 63. Stanke D, Bradway B., Hallstrom A. et al. Managing England. 1999. Building Moisture. Trane. American Standard, Inc. La Crosse, Wisconsin. Sys-AM-15. 1998. 53. Committee C-11 on Gypsum and Related Building Materials and Systems. From mud and reeds to walls 64. Flannigan B, Morey PR. Control of moisture problems and ceilings. ASTM Standardization News. (27)7: 30-33. affecting biological indoor air quality. ISIAQ Guideline July 1999. (Deleted) TFI-1996. International Society of Indoor Air Quality and Climate. 1996.

68 65. Shaughnessy RJ, Morey PR, Cole EC. Prevention and 72. Ritschkoff AC, Viitanen H, Koskela K. The response of control of microbial contamination. IN: Bioaerosols building materials to the mould exposure at different Assessment and Control. Janet Macher, ed. American humidity and temperature conditions. IN: Proceedings of Conference of Governmental Industrial Hygienists. Healthy Buildings 2000. SIY Indoor Air Information. Cincinnati, Ohio. 1999. Finland. 2000.

66. Flannigan B. Approaches to assessment of microbial flora 73. ASHRAE Handbook Fundamentals. American Society of of buildings. IN: IAQ ’92, Environments for People. Heating, Refrigerating and Air-Conditioning Engineers, American Society of Heating, Refrigerating and Air- Inc. Atlanta, Georgia 1989 as reported in Odom, JD, Conditioning Engineers, Inc. Atlanta, Georgia. 1992. As DuBose G. Preventing Indoor Air Quality Problems in reported in: Shaughnessy RJ, Morey PR, Cole EC, 1999. Hot, Humid Climates: Problem Avoidance Guidelines. CH2M Hill. Orlando, Florida. 1996. 67. Rautiala S, Pasanen AL, Kasanen JP, et al. The effect of fluctuating humidity and temperature conditions on 74. Brown GE. Chapter VI. Construction. IN: Mold & Mildew in microbial growth on three construction materials. IN: Hotel and Motel Guestrooms in Hot and Humid Climates. Indoor Air 99 Proceedings of the 8th International John P.S. Salmen and James A. Diluigi, eds. The Conference on Indoor Air Quality and Climate. Hospitality Lodging & Travel Research Foundation. Construction Research Communications, Ltd. London, Washington, DC. 1991. England. 1999. 75. Burch DM, Sanders, CA. A Computer Analysis of Wall 68. Thermal and moisture control in insulated assemblies – Construction in the Moisture Control Handbook. NISTR applications. IN: ASHRAE 2001 Handbook: 5627. Building and Fire Research Laboratory. National Fundamentals. American Society of Heating, Institute of Standards and Technology. Gaithersburg, Refrigerating and Air-Conditioning Engineers, Inc. Atlanta, Maryland. 1995. Georgia. 2001. 76. Burch DM, Zarr RR, Fanney AH. Experimental verification 69. Thermal and moisture control in insulated assemblies – of a moisture heat transfer model in hygroscopic regime. applications. IN: ASHRAE 2001 Handbook: IN: Proceedings of Thermal Performance of Exterior Fundamentals. American Society of Heating, Envelopes of Buildings VI. December 4-8, 1995. Refrigerating and Air-Conditioning Engineers, Inc. Atlanta, Clearwater Beach, Florida. American Society of Heating, Georgia. 1993. Refrigerating and Air-Conditioning Engineers, Inc. Atlanta, Georgia. 1995. 70. Kuenzel HM. More moisture load tolerance of construction assemblies through the application of a smart vapor 77. Mold and Mildew: An Overview/Wallcovering: The retarder. Proceedings from the Thermal Performance of General Purpose Coated Fabrics Division of the Exterior Building Envelope VI Conference. American Chemical Fabrics & Film Association. Cleveland, Ohio. Society of Heating, Refrigerating and Air-Conditioning 1995. Engineers. Atlanta, Georgia. 1998.

71. Gatley DP, Ehle WF. Chapter V. Mechanical system design. IN: Mold & Mildew in Hotel and Motel Guestrooms in Hot and Humid Climates. John P.S. Salmen and James A. Diluigi, eds. The Hospitality Lodging & Travel Research Foundation. Washington, DC. 1991.

69 Index

Adhesives, 5, 7, 13, 19, 33, 43, 44, 50 Plaster, 15, 25, 26, 42, 51, 63 Air barriers, 38, 39, 46 Plywood, 7, 9, 15, 25, 41, 64 Air infiltration (or intrusion), 10, 11, 36, 40, 61, 62 Pressed wood, 7, 9, 24, 32 Air leakage, 10, 26, 37 Roof (roofing), 8-10, 24, 26, 36, 37, 61-64 Air sampling, 18, 23, 24, 26-28 Semi-porous, 30, 32 American Hotel and Motel Association, 4 Soffit, 36, 64 American College of Occupational and Environmental Medicine, 20 Studs (metal and wood), 25, 32, 33, 37-39 American Conference of Governmental Industrial Hygienists (ACGIH), Timber (lumber), 26, 65 20, 27, 34, 48 Wood, 7, 9, 13, 17-19, 24-26, 32, 37, 41, 63-65 American Industrial Hygiene Association (AIHA), 28, 48, 65 Building American Society of Heating, Refrigerating and Air-Conditioning Construction process (sequence), 45-47 Engineers (ASHRAE), 46, 48, 53 Design, 45, 46 American Society of Testing and Materials (ASTM), 14, 50, 52, 56 Design team, 46 Allergens, 4, 6, 13, 21, 27, 63 Failure of, 1, 45 Allergic reactions (allergenic), 21, 63 Building occupants, 4, 6, 7, 28, 33, 36, 46, 59 Antimicrobial agents (compounds), 7, 32, 33 Activities, 7, 10, 11, 29, 36, 59 Assessment, 1, 23, 28 Health effects, 24, 27 Guidelines, 24, 30 Interviews, 24 Plan, 26 Building practices (good), 1, 37, 43 Asthma, 4, 21 Surface preparation, 41 Wallcoverings installation, 43, 44 Building pressurization, 10, 36-38 Backings (or substrate), 5, 13, 50, 51, 52 Negative, 9, 10, 24, 34, 36 Paper, 13, 14, 50, 51 Positive, 9, 36-38, 40, 46, 62 Coated woven fabric, 13 Building tightness, 7, 8, 36, 58 Coated non-woven fabric, 13 Burge, Harriett, 10, 20 Fabric-backed vinyl, 50 Latex acrylic, 13 Non-woven, 14, 50 Calcium hydroxide, 33 Vinyl-coated paper, 50 California Department of Health Services, 48 Woven, 50 California Research Bureau, 48 Capillary action, 8, 37 Barriers (or retarders), Cellulose, 5, 7, 13, 15, 16, 18, 19, 51 Air, 38, 39, 46 Certifications, 23 Rainwater, 37 Chemical Fabric & Film Association (CFFA), 1, 50, 52 Smart, 39 Cleaning solutions Vapor, 9, 14, 15, 36, 38, 39, 40, 46, 53 Detergent, 31, 32, 44 Weather, 46 Diluted bleach, 31, 44 Bioaerosols, 20, 34 Zinc sulfate, 42 Bioaerosol sampling, 29 Climate, 1, 6, 14, 38, 39, 46, 53 Biocides (mildewcides), 7, 32, 33, 44, 63 Heating (mixed or cold), 9, 38-40, 46, 54, 59 Building envelope, 7- 10, 36-40, 53, 63 Cooling (hot and humid), 4, 9-12, 36, 38-42, 45, 46, 53-55, 59 Building components, materials, 5, 7-10, 17, 20, 24-26, 32, 35, 36, 37, Dry, 17 40, 47, 53 Hot (or warm) 10, 17, 58 Brick (or masonry), 8, 26, 37, 42 Coatings Cardboard, 24 Acrylic, 16 Carpet, 5, 7, 18, 19, 24, 26, 31, 32, 40 Adhesive-coating transparent surface, 27 Ceilings, 24, 33, 36, 38, 40, 46, 53, 60, 63, 64 Adhesion, 52 Ceiling tiles, 7, 9, 24, 26, 31, 34 Clays and calcium carbonate, 16 Cement, 8, 15, 18, 37, 41, 47 Epoxy, 16 Cleaning, removing, 31 Emulsion polymers, 16 Concrete, 9, 17, 25, 32, 41, 42 Polymer (protective), 12, 16 Fire-proofing, 47 Wallcovering, 16 Gypsum wallboard (drywall), 5, 7, 19, 24-28, 31-33, 37-39, 41-44, Condensation, 7, 9-12, 24, 28, 36-40, 44, 53, 54, 59-62 46, 47, 51, 61, 63 First plane of, 38 Heating, ventilating and air-conditioning (HVAC), 6, 8-10, 22, 25, Construction process (sequence), 45-47 27, 31, 32, 36-38, 40, 46, 59, 60, 62, 63 Containment Insulation, 7-9, 15, 18, 19, 25, 31, 32, 38, 39, 41 Full-scale, 34 Non-porous, 30, 32 Local, 34 Oriented strand board (OSB), 7, 9, 15, 64 Source, 34 Paneling, 7, 43, 51 Paper, 7, 13, 15, 17, 19, 24, 42 Porous, 7, 9, 25, 30-32 Decorative layer, 12, 16, 50, 52

70 Design, 45 Insulation, Practices, 46 Building, 7-9, 15, 25, 31, 32, 38, 39, 41 Team, 46 HVAC (fiber-glassed lined, duct), 7, 18, 19 Dew point, 9-11, 38, Urea formaldehyde foam, 9 Drainage, 8, 9, 24, 37 Intermediate layer (ground), 12, 50 Drywall (Gypsum wallboard), 5, 7, 19, 24-28, 31-33, 37-39, 41-44, 46, International Society of Indoor Air Quality and Climate, 48 47, 51, 61, 63

Lawrence Berkeley National Laboratory, 22 Fiberoptic equipment, 25 Leaks Filters, high efficiency particle air (HEPA), 31, 32, 34, 35 Air, 10, 26, 36 Fire ratings (wallcoverings), 61 Building envelope, 7, 36, 37, 42, 59 Foundation of the Wall and Ceiling Industry, 1 Doors, 8 Fungi, see Mold Foundation, 8 Plumbing, 8, 24, 30, 62 Roof, 8, 61, 62 Gotts, Ronald, 22 Structural faults (failure), 9, 24, 30, 36, 59 Guidelines (specifications), Water (penetration), 24, 60, 61 American Society of Testing and Methods (ASTM), 14, 15, 50, 52, 56 Windows, 8, 24 Assessment and remediation, 24, 30, 31, 42, 48, 49, 60 Chemical Fabrics & Film Association (CFFA), 15, 50, 52 Construction, 46 Microbial volatile organic compounds (MVOCs), 6, 20, 64 Containment, 32, 24, 58, Microbial levels, 26 Design, 46 Mildew, 1, 2, 5, 6, 7, 10, 11, 16, 18, 42, 43, 53, 58, 60-62, 64 Federal (wallcoverings), 50 Mildewcides (biocides), 7, 32, 33, 44, 63 Microbial testing, 28 Minnesota Department of Health, 48 Personal protection, 32, 34, 58 Moisture (see also Water or Vapor), 1, 5, 8-10, 16, 17, 38, 45, 53, 58-61 Activity (Content), 10, 37, 41, 42, 53, 65 Condensation, 7, 9-12, 24, 36-40, 59-62 Heating, ventilating and air-conditioning (HVAC), 6-10, 22, 25, 27, 31, Elimination of, 2, 10, 16, 36, 59, 61 32, 36-38, 40, 46, 59, 60, 62, 63 Excessive, 2 Health Canada, 48 Generation, 7, 11, 36 Health effects from mold (hazards problems), 4-6,17, 19-21, 24, 28- Intrusion, 11, 40, 45 30, 35, 58 Levels (or loads), 8, 11, 39, 40, 41 Hidden mold, 6, 10,24, 43, 63 Measurements, 26 High efficiency particle air filters (HEPA), 31, 32, 34, 35 Sources, 1, 40, 61, 62 HIV/AIDS, 20 Vapor, 2, 7-11, 14, 15, 35, 36, 39, 40, 56-60 Hospitality Lodging & Travel Research Foundation, 10, 11 Moisture meters, 25 Humidity (relative or ambient), 8-10, 14, 15, 18, 22, 36, 37, 39, 40-42, Delmhorst BD-2100, 25 45, 46, 53, 56, 57, 62 Gypsum scale, 25 Hypersensitivity pneumonitis, 20, 21 Impedance, 25, 26 Hyphae, 17, 20, 21, 27, 58, 63 Pad, 25, 26 Pinless, 25, 26 Pin-type resistance, 25 Immune systems (function), 17, 20, 21, 64 Reference scale, 25 Indicator organisms, 28, 29 Wood scale, 25 Indoor Air Quality Association (IAQA), 48 Mold (or Fungi) Indoor Environmental Standards Organization (IESO), 48 Ascomycetes, 18 Indoor/outdoor ratios, 18, 28, 29, 35 Basidiomycetes, 18 Indoor pollutants Chlamydospores, 17 Bacteria, 17, 22 Common indoor, 17, 19 Carbon dioxide, 8, 20, 22 Eukaryotes, 17 Carbon monoxide, 22 Exposure to, 5, 6, 19-21, 28, 32, 34, 58, 64, 65 Formaldehyde, 8 Germination, 17 Microbial volatile organic compounds (MVOCs), 6, 20, 64, Health effects from (hazards or problems), 4-6, 17, 19-21, 24, 28- Microbiological, 22 30, 35, 58, 64, 65 Pollen, 22 Hidden growth, 6, 10, 24, 43, 63 Viruses, 22 Indicator organisms, 28, 29 Volatile organic compounds (VOCs), 8, 20, 22 Indoor/outdoor ratios, 18, 28, 29, 35 Infrared sensors, 26 Hyphae, 17, 20, 21, 27, 58, 63 Inspections Mycelium, 17, 63, 64 Olfactory, 24 Spores, 6, 11, 16, 17, 20, 40, 43, 58, 65 Visual, 23, 24, 27 Stains, 24, 42, 44

71 Toxic (toxigenic), 6, 18, 22, 29, 65 Proteins (microbial), 20 Visible growth, 6, 23, 24, 26, 28, 32, 44, 59, 64 Rainwater barriers, 37 Zygomycetes, 18 Remediation, 1, 24, 26, 30, 35, 59, 64 Mold species, 16, 19 Experts, 23 Acremonium sp., 5 Guidelines, 24, 60 Alternia alternata, 19 Plan, 23, 26 Aspergillus versicolor, 5, 19, 21 Procedures, 26 Apergillus fumigatus, 19 Restoration, 30 Aureobasidium pullulans, 5, 18 Retarders (vapor), 15, 39, 46, 53 Chaetomium globosum, 5 Chaetomium sp., 19 Cladosporium sp., 18 Sampling (or samples), 23, 26, 28, 29, 35 Cladosporium sphaerospermum, 19 Air, 18, 23, 24, 26-28 Fusarium sp., 19, 21 Analyses, 26, 27 Geotrichum sp., 19 Bioaerosol, 29 Isopenicillin N., 16 Bulk, 28 Paecilomyces sp., 19 False negative results, 26 Paecilomyces variotii, 9 Guidelines, 48 Papulospora sp., 19 Indicator organisms, 29 Pennicillium chrysogenum, 5 Indoor/outdoor ratios, 28 Pennicillium exapansuum, 5 Methods, 27 Pennicillium funicolosum, 5 Sampling protocol, 27 Pennicillium sp., 9, 16, 19, 21 Source (or surface), 23, 26, 35 Phoma sp., 5, 18 Testing criteria, results, 28 Rhodotorula sp., 18 Seasonal variations, 28, 37 Saccharomyces cerevisiae, 16 Sealers, 42 Scopulariopsis sp., 5, 19 Semi-porous (building materials) 30-32 Stachybotrys alternans, 18, 19 Sheet Metal and Air-Conditioning Contractors National Association Stachybotrys atra, 18, 19 (SMANCA), 48 Stachybotrys chartarum, 5, 18, 19, 21, 22 Sick building syndrome, 22 Trichoderma sp., 5, 19 “Smart” vapor retarders, 39 Trichoderma harzianum, 9 Specification (guidelines), Tylipocladium infatum, 16 American Society of Testing and Methods (ASTM), 14, 15, 50, 52, Ulocladium sp., 19 56 Wallemia sp., 5 Assessment and remediation, 24, 30, 31, 42, 48, 49, 60 Mycelium, 17, 63, 64 Chemical Fabrics & Film Association (CFFA), 15, 50, 52 Mycotoxins, 6, 19, 20-22, 58, 64 Construction, 46 Containment, 32, 24, 58, Design, 46 National Institutes of Health (NIH), 20 Federal (wallcoverings), 50 New York City Department of Health, 48 Microbial testing, 28 National Institute of Science and Technology (NIST), 48, 53 Personal protection, 32, 34, 58 NIST Personal Computer Model (MOIST), 46, 53, 54, 55 Spores (mold), 6, 11, 16, 17, 20, 40, 43, 58, 65 Non-porous (building materials), 30-32 Sound meters, 26 Nutrients, 20, 36, 41, 43 Stains, 24, 42, 44 Cellulose, 5, 7, 13, 15, 16, 18, 19, 51 Studs (metal and wood), 25, 32, 33, 37-39 Sources, 6, 7, 10, 16, 17, 58 Substrate (building materials), 5, 10 Substrate (or backing), 5, 13, 50-52 Paper, 13, 14, 50, 51 Occupational Safety and Health Administration (OSHA), 20 Coated woven fabric, 13 Odors, 23, 24, 59 Coated non-woven fabric, 13 Fabric-backed vinyl, 50 Latex acrylic, 13 Paint, 5, 38, 42, 53 Non-woven, 14, 50 Permeability, 11, 12, 16, 36, 40, 46, 58 Vinyl-coated paper, 50 Ratings, 13, 14 16, 60 Woven, 50 Test methods, 14 Surface preparation, 41-43 Walls, 54, 55 Masonry, 42 Wallcoverings, 2, 7, 11-16, 35, 38, 41, 46, 50, 51, 60, 61 New drywall, 42, 43 Permissible exposure limits (PELs), 20 New plaster, 42 Personal protective equipment (PPE), 34 Old wallcovering, 43 Porous (building materials), 7, 9, 25, 30-32 Paint, 42 Primers, 7, 33, 42, 43, 44 Paneling, 43

72 Temperature, 6, 7, 9-12, 16, 22, 36, 38-41, 53, 54, 56-58 Wallcoverings, 1, 37, 38, 40, 58-60 Threshold limit values (TLVs), 20 Acoustical, 51 Toxigenic compounds, 6 Backings (or substrate), 5, 13, 14 50-52 Toxigenic mold (or fungi), 18, 22, 29, 65 Booking, 44 Characteristics of, 50-52 Coatings, 16 U.S. Centers for Disease Control and Prevention (CDC), 49 Construction, 12-14, 16, 50-52 U.S. Department of Housing and Urban Development (HUD), 14 Cork, cork veneer, 13, 51, 52 U.S. Environmental Protection Agency (EPA), 22, 49 Decorative (or design) layer, 12, 16. 50, 52 University of Minnesota Department of Environmental Heath and Discoloration of (stains), 2, 24, 42, 44 Safety, 18, 49 Fiberglass (woven), 15, 16, 51 Fire ratings for, 61 Heavy-weight paper, saturated paper, 51 Vapor barriers, 9, 14, 15, 36, 38-40, 46, 53 Installation of, 2, 7, 13, 33, 41-44 Vapor impermeable (vapor barriers), 15 Intermediate layer (ground), 12, 13 Vapor permeable (breathable), 15 Microvented (perforated), 14, 16, 41, 60, 61 Vapor retarders, 15, 39, 46, 53 Materials, 13, 15, 16 Vapor semi-permeable (vapor retarders), 15 Natural, 15, 16, 51, 52 Vapor transmission Non-woven, 13-16, 44, 50-52, 61 Calculation, 56, 57 Old, 43, 44 Dry cup, 56 Permeability of, 2, 7, 11-16, 35, 38, 41, 46, 50, 51, 60, 61 Rate, 56 Polyolefin/synthetic textiles, 16, 51 Sample limitation, characterization, 56 Products, 1, 2, 4, 7, 8, 12, 13, 15, 44, 51, 60 Testing (test methods), 13, 14, 56, 57 Saturated paper, 15, 16, 51 Wet cup, 56 String effects, 13, 51 Ventless gas appliances, 11 Textiles (or woven), 13, 15, 16, 51, 60 Vinyl wallcoverings, 12-14, 33, 61 Underliner, 51 Fabric-backed vinyl (FBV), 50 Vinyl, 12-14, 33, 50, 60, 61 Paper-backed vinyl/solid sheet vinyl (PBV), 50, 60 Wood veneer, 51 Rigid vinyl sheet, 50 Woven, 13, 15, 16, 44, 50-52, 60 Vinyl coated paper, 50 Wallcoverings Association, 1, 2 Visible mold growth, 6, 23, 24, 26, 28, 32, 44, 59, 64 Wallboard, see Drywall Volatile organic compounds (VOCs), 8, 20, 22 Washington State Department of Health, 49 Water (see also Moisture or Vapor), 5, 9 Activity (aw), 10, 37, 41, 42, 53, 65 Walls Damage, 5, 22-24, 26, 46 Cavity (system), 9-12, 36, 38, 40, 46, 53, 59, 62 Infiltration, 7, 8, 37 External, 10, 46. 53, 54 Penetration (leaks), 24, 61, 62 Finishes, 46 Installation of wallcoverings, 42, 43 Internal surfaces, 10, 31, 32, 40-44, 46, 53, 54 Permeable, 54, 55

The Wallcoverings Association Chemical Fabrics & Film Association 401 N. Michigan Avenue; Chicago, Illinois 60611 1300 Sumner Avenue; Cleveland, Ohio 44115-2851 Phone (312) 644-6610 Fax (312) 527-6705 Phone (216) 241-7333 Fax (216) 241-0105 www.wallcoverings.org www.chemicalfabricsandfilm.com Cause, Effect and Response

MoldA Study of Wallcovering Products

Visit the WA Website at www.wallcoverings.org or the CFFA website at www.chemicalfabricsandfilm.com for updates/errata to this document.