Category A Healthy. House

Alternatives to paper-backed gypsum board are now available. The following products may be used to replace it and are especially use­ful in applications where moisture conditions may promote mold growth:

• Dens Armor Plus is an alternative to regu­lar cardboard-backed panels. It is paper­less, faced on two sides with a glass mat, and highly mold resistant.

• Magnesium oxide boards: Currently these products are being manufactured in China. They can be used to replace gypsum board, plywood, cement boards, and oriented strand board (OSB). They resist moisture, bugs, fungus, mold, and fire. Products are available in North America under the prod­uct names Dragonboard, MagBoard, and Strong-Enviro Board.

Tile

Tile is generally an inert and healthful floor, wall, and counter surfacing material. We rec­ommend factory-finished tiles that require no further finishing onsite. Many attractive and reasonably priced tiles are rated for com­mercial and exterior use. This rating almost guarantees a low-maintenance, long-wearing product that will not require onsite refinish­ing.

The following concerns must be addressed in order to achieve a healthful installation:

• In standard construction, tile is often laid over an unacceptable backing such as par­ticleboard, which contains high formalde­hyde levels.

• In wet areas, tile is frequently laid over green board (a gypsum board that has par­affin wax mixed with the gypsum to pre­vent it from falling apart). However, the paper on the board will still develop mold in the presence of moisture.

• Certain imported tiles contain lead-based glazes or asbestos fillers. Lead content can be simply verified with a lead swab test (see Chart 13 л).

• Certain glazes, primarily imports, have been found to be radioactive, especially cobalt blues and burnt oranges.

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• Many tile-sealing products contain harm­ful chemicals and high levels of VOCs. Selecting tiles with commercially rated finishes and glazes will bypass the need to use tile sealers on the construction site.

• Some standard tile adhesives and mortars contain harmful chemicals.

• Standard grouts usually contai n fungicides and latex additives.

• Grouts are porous and can harbor mold and mildew. They should be sealed where exposed to water.

Underlayment for Ceramic Tile

The following are acceptable underlayments for ceramic tile:

• A clean, level concrete slab or gypsum con­crete base that has been fully cured.

• Exterior-grade plywood that has been aired out and sealed. Use only where a ce­mentitious underlayment is unavailable.

This method will require mastic adhesive and is not recommended for areas that get wet.

• A lightweight, strong, noncombustible, highly water-resistant cementitious board such as Durock, Hardibacker Board, or PermaBase.

Tile Installation

The three basic methods for installing tiles are thicksetting, thinsetting, and adhesion with organic mastics.

Thickset Method

This is the tried and true, old-fashioned way of adhering tiles, prevalent prior to the invention of additives. A thick reinforced bed of mor­tar consisting of Portland cement, sand, and in some cases lime is floated. While the base is still plastic, a thin layer of Portland cement paste known as the bond coat is spread over
it. The tile is adhered to the bond coat and al­lowed to cure for several days before the tile is grouted.

This method will create the strongest, most durable tile installation available without the use of chemical additives. The following should be specified for this type of installation:

• Use only additive-free Portland cement, clean sand, lime where required, and po­table water. Use the recommended rein­forcing and specified cleavage membrane.

• For wall, ceiling, and floor installations, follow the method covered by ANSI AI08.1 and set the tiles on the mortar bed while it is still plastic.

• The cleavage membrane shall be non­asphalt-impregnated, 4 millimeter poly­ethylene such as Cross Tuff, Tu Tuf 4, or an approved equivalent.

It is not always possible to use a thickset instal­lation. The iW-inch depth required for thick­setting may not be available unless carefully planned from the outset. Tile setters skilled in this method are sometimes difficult to locate. This method is labor-intensive and will be more costly than other installation methods.

Thinset Method

Tliinset mortars are powdered sand and ce­ment products mixed with liquid and spread to a thickness of approximately Vs to Ys of an inch. Once dried they are unaffected by water and can be used in wet applications.

A variety of thinsets are available. Most thinset mortars contain various chemical ad­ditives to enhance workability, flexibility, and bonding strength, thus expanding the range of application. Water-mixed thinsets consist of powdered sand and cement. They are available with or without powdered latex and acrylic additives and are mixed onsite with water. Latex and acrylic thinsets consist of powdered sand and cement mixed with liquid latexes and acrylics instead of water. They have higher bond and compressive strength and improved flexibility compared to water-mixed thinsets. Epoxy thinsets develop bonds more quickly than other thinsets. The epoxies emit nox­ious fumes while curing and these fumes can be absorbed by porous surfaces. The use of epoxies is almost always unnecessary in res­idential construction. If epoxies are used, workers should wear protective vapor respira­tors during application and the space should be continuously aired out until all fumes have dissipated. The additive ingredients used in these thinset mixtures are proprietary and not disclosed on the label. When selecting a thin­set product, choose one that can do the job at hand with the smallest amount of chemical additives and the least odor.

Thinsets Without Synthetic Additives

The following water-mixed thinsets are avail­able without synthetic additives. They gain their strength through the use of high-quality Portland cement, but are generally considered to be less flexible and more prone to cracking than thinsets with latex additives. They may be used successfully over clean concrete slabs, properly supported cementitious boards, and mortar beds.

• C-Cure FloorMix 900, Thinset 911 (dual purpose), andWallMix9oi: The “economy” line of C-Cure mortars, which contain no additives other than mineral salts

• Laticrete Additive Free Thinset

Low-О dor Thin sets with Vinyl Polymer Additives

The following water-mixed thinsets con­tain vinyl polymers, which give them greater strength and range of application. They have very little odor and are virtually odorless once cured. However, anyone with sensitivities to vinyl polymer additives is advised to test these products prior to using them.

• C-Cure MultiCure 905: A latex-en­hanced, dry-set mortar with added bond­ing strength and flexibility for use over cementitious and plywood substrates

• C-Cure PermaBond 902: A dry-set mor­tar with Portland cement, sand, and addi­tives for use over cementitious substrates

Gypsum board, also known as gypboard, Sheetrock, or drywall, is the most common form of interior wall sheathing in modern res­idential construction. It is considerably less expensive than plaster. The 4- by 8-foot sheets are attached to the studs, then taped, sealed, textured, and painted.

Gypsum board is composed of natural gyp­

sum sandwiched between two sheets of card­board made from recycled newsprint. This cardboard backing creates problems when water damage occurs because it is a nutrient that encourages mold growth. In his mold in­vestigation work, John Banta has seen many cases where mold has begun to grow less than 72 hours after water damage occurs. Getting immediate help from a remediation specialist with the proper drying equipment is often the key to saving money and health when a water disaster occurs. A skilled specialist will know how to safely remove mold while isolating it so that no further contamination occurs.

Gypsum Board Installation

The installation of gypsum board in standard practice may negatively affect indoor air qual­ity for the following reasons:

• Dust and debris within wall cavities are often enclosed and concealed by the gyp – board. If dust and debris are not cleaned
out, they can cause problems over time. Dust can eventually work its way back into the living space and become a main­tenance problem as well as an air pollutant, and other construction debris can become a breeding ground for mold if it becomes wet.

• Gypsum board itself will outgas because of the inks remaining in the recycled news­paper. To seal in the small quantity of un­desirable VOCs generated by the surfacing board, the walls may be primed with a spe­cialty paint or primer. With the printing industry shift to soy-based ink, outgassing may become less of a problem.

• The standard premixed joint compounds may contain several undesirable chemi­cals, including formaldehyde.

• Like plaster, gypsum board is highly ab­sorbent. In standard practice, gas and ker­osene heaters may be used to dry the joint compounds. The byproducts of combus­tion are absorbed into the walls and will outgas into the building envelope of the completed home.

• Special gypsum boards are made for use in areas that get wet, such as showers, tub surrounds, and countertops. When walls using these products in wet areas are dis­assembled after several years, the water re­sistant papers are often moldy, especially at the joints between boards. Cementitious boards without paper backing are made to be used as backerboard in wet locations and do not have the same mold problems that are associated with the paper-backed products.

To avoid these problems, include the follow­ing specifications:

• All wall cavities shall be thoroughly vacu­umed and free of debris prior to installa­tion of the gypsum board.

• Joint compound shall be a powdered joint cement and texture compound such as Murco M-ioo HiPo or approved equal that is formulated with inert fillers and without formaldehyde or preservatives.

• Heaters fueled by gasoline or kerosene are prohibited.

• If relative humidity rises above 55 percent, electric dehumidification shall be applied until relative humidity remains consis­tently between 45 and 55 percent without additional dehumidification. Interior sur­face temperatures shall remain above 50 degrees.

• The joint compound must be completely dry before primer is applied.

• In wet areas such as showers, tub sur­rounds, and sink counters, cementitous backerboard without paper backing shall be used. Durock, Hardibacker Board, Permabase, or approved equal maybe used for this purpose.

Creating an Air Barrier with Gypsum Board

In 2X frame wall construction there are often undesirable emissions from materials used in the building envelope. Since, even with the greatest care in choosing materials, there may not be completely inert, cost-effective prod­ucts available, it often makes sense to create an airtight barrier on the inside face of the building envelope to block the entry of unde­sirable substances from within the wall cavity itself or from adjoining environments. This also makes great sense from the standpoint of moisture control and energy efficiency. A tightly sealed and taped gypsum board wall, in combination with gasketed or foamed sill and top plates and thorough sealing around all openings (windows, electrical outlets, plumb­ing penetrations, and recessed lighting), will create an airtight barrier that can perform the same function as an air barrier made of care­fully joined plastic sheeting as described in the section on air barriers in Division 7.

This type of airtight assembly will pre­vent airborne moisture from pouring through cracks into the wall but will allow a small amount of moisture to be carried through by diffusion. In climatic conditions where the building would tend to dry to the inside (i. e., when the inside temperature of the building is cooler than the outside temperature), the gypsum board assembly will also allow mod­erate amounts of moisture in the wall cavity to dry out instead of remaining trapped. Be­cause gypsum board allows some water vapor to move through it, this is a superior solu­tion for blocking chemical gases out of living spaces. This is especially relevant where air conditioning is used and moisture would tend to condense on a layer of impermeable plas­tic sheeting (if one were present) and remain trapped in the wall cavity.

Gypsum board can store limited amounts of moisture before it begins to mold. It will not stand up to large amounts of wetting. In hot, humid climates there must be a sufficient vapor barrier on the exterior of the building to prevent excessive moisture from penetrating the wall from the outside and causing the card­board on the gypsum board to mold. Similarly, in heating conditions it may be necessary to use a paint or primer with a low permeability rating to retard some of the water vapor that would naturally diffuse through the gypsum board. 86001 Seal is a primer that has a low enough rating to serve as a vapor retardant.

Gypsum board can be purchased with foil backing. Although foil is an excellent vapor blocker, we do not recommend it because it is problematic if water damage occurs. As­sessment is hampered because the foil pre­vents a moisture meter from taking accurate readings. It is also more difficult to dry out a flooded wall cavity when foil-backed gypsum board has been used.

To summarize, using gypsum board in an airtight manner on stud frame construction makes sense in all climatic conditions. How­ever, this is only one part of the moisture con­trol strategy. Developing an overall strategy for the control of moisture in any building must take into account the climatic conditions of the site. The best solution will be different for different locations. While a full discussion of moisture movement and best solutions is beyond the scope of this book, an understand­ing of moisture movement is essential for the ongoing success of a health-enhancing build­ing in all but the most forgiving dry climates. To this end, we highly recommend the Build­ers Guides by Joseph Lstiburek, listed at the end of Division 7.

From a Building Biology standpoint, clay – based plasters provide a superior wall finish because of the remarkable hygroscopic prop­erties of clay. For more information about mixing your own plasters, we recommend The Natural Plaster Book (listed at the end of this chapter). Resources for commercially pre­pared clay-based plaster are:

• American Clay Enterprises: A variety of clay-based plasters for interior finish­ing, including three texture styles and 42 colors.

• Japanese Wall: Several lines of interior and exterior natural plasters imported from Japan. All-natural, nontoxic plasters contain sand, diatomite earth, clay, natural stone chips, and straw.

Plaster Finish

Because of the porous nature of plaster, it will stain and show fingerprints if left unfinished. Plaster walls, which were the norm before the advent of gypsum board or Sheetrock, were commonly painted or covered with wallpaper. Today, homeowners enjoy the organic feel of the color variations in natural plaster and it is fashionable to leave it unpainted. Most people prefer to apply a clear finish over it to protect and enhance its natural beauty, or to leave the plaster unsealed.

Natural beeswax finishes will protect the wall while maintaining its permeability. Tra­ditionally, beeswax was applied with a hot knife and troweled on the wall. There are very few craftsmen who know this art form today. However, we have found that a natural bees­wax furniture polish can be applied with a cloth and buffed. As with all plant chemis­try products, chemically sensitive individuals may find the scent objectionable and should test a small sample first.

Some synthetic finishes will create a more impervious seal and are less expensive, easier to apply, and more enduring. Synthetic finishes should be carefully evaluated for chemical content and outgassing. Some maybe toxic or increase problems with static electricity. Since most make the surface nonporous, they may encourage mold growth on the paper back­ing of the gypsum lathing behind the plaster if moisture becomes trapped. So, as with gyp­sum board, if a water accident occurs it should be quickly dried. We have successfully used the following finishes:

• American Clay Black Soap Finish: A

gelatinous castile soap infused with potash

to enrich color and create a soft patina

This Santa Fe Style interior combines hard trowelled plaster wall finishes with brick flooring and stone de­tailing to create a healthy interior. Architect: Baker-Laporte and Associates; Builder: Prull and Associates. Photo: List Dennis.

• American Clay Gloss Sealer: Low-VOC product used for high-traffic areas, pro­viding water resistance to walls; easy to clean

• American Clay Penetrating Sealer: A

low-VOC soy resin/acrylic spray-on sealer that increases durability and water resis­tance

• Livos Glievo Liquid Wax: Apply a thin coat and hand buff

• Окоп Seal and Finish: For satin gloss

P. F. is a 54-year-old woman who was in good health until 1981 when she moved into a new mobile home. Shortly thereafter she developed a digestive disorder with gas and bloating, severe insomnia, and a chronic cough with frequent epi­sodes of bronchitis. By the following year she was suffering from persistent fatigue and frequent respiratory infections, including her first case of pneumonia. She became sensitive to most prod­ucts containing formaldehyde, especially press – board. She noted that she experienced "brain fog" while shopping at the local mall. Her symptoms continued to worsen, and now included allergies, hypoglycemia, and lethargy.

P. F. consulted with several healthcare practi­tioners, including a pulmonary specialist, psychia­trist, hypnotist, nutritionist, and acupuncturist. None of them ever questioned her about the air quality in her home. Eventually she received the diagnosis of multiple chemical sensitivity from a physician with similar symptoms, and was fi­nally educated about the underlying cause of her health problems. In 1992, P. F. moved into a house that contained low formaldehyde levels, alleviat­ing some of her symptoms. Her house contained several healthful features such as radiant heat in concrete floors and the absence of pressboard and particleboard in its construction.

However, further modifications were neces­sary before her health could be stabilized and im­proved. All gas appliances were removed; filtration was installed for both air and water; and the me­chanical room was vented to the outside. By 1996, P. F. had regained her health. However, as is typi­cal in such cases, she still becomes symptomatic on reexposure to toxic fumes and must diligently maintain a"safe"environment for herself.

Discussion

Indoor formaldehyde is gaining recognition as a severe health hazard for occupants of homes and office buildings where chronic exposure occurs. Several organizations, such as the American Lung Association, have recommended that formalde­hyde levels not exceed 0.1 part per million. People who have already become sensitized to formal-

minor cracks. To maintain a good barrier, these gaps should be filled with an acceptable sealant. Since most of the initial cracking will take place during the first 18 months while the house is settling, it makes sense to wait and do all of these minor repairs at once. In pumice – crete, clay/straw, and adobe construction, the plaster may be applied directly to the wall ma­terial (see Division 4).

Although most plasters are inert, some contain polyvinyl additives that are subject to outgassing and should be avoided. Verify the presence of additives with the manufacturer prior to purchase.

One potential health hazard associated with plaster lies in the method by which it is dried. Because new plaster releases a signifi­cant amount of moisture, it is necessary to dry it out quickly so that other building ma­terials are not adversely affected. This is espe­cially problematic in the winter months, when cold temperatures and lack of ventilation slow down the rate of evaporation. The standard solution is to use gasoline or kerosene heaters, dehyde will have reactions at levels as low as 0.02 part per million. Approximately 50 percent of the population is exposed on a daily basis in the work­place to levels that exceed the 0.1 part per million limit. Mobile homes are notorious for causing health problems because of the extremely high levels of formaldehyde emitted from the plywood and particleboard used in their construction.3

Individuals who develop permanent health problems associated with formaldehyde exposure often relate the onset of their symptoms to a flu­like illness, which is diagnosed as a viral infection. However, the affected individual usually does not totally recover from this so-called flu and is left with general malaise, fatigue, and depression. Other symptoms can include rashes, eye irritation, frequent sore throats, hoarse voice, repeated sinus infections, nasal congestion, chronic cough, chest pains, palpitations, muscle spasms, joint pains, numbness and tingling of the extremities, colitis and other digestive disorders, severe headaches, dizziness, loss of memory, inability to recall words and names, and disorientation. Formaldehyde is an immune system sensitizer, which means that chronic exposure can lead to multiple allergies and sensitivities to substances that are entirely unrelated to formaldehyde. This is known as the "spreading phenomenon."

P. F. was typical of people whose multiple chemical sensitivities stem from formaldehyde ex­posure in that she consulted numerous physicians and specialists in an attempt to obtain a diagnosis. Physical examinations and standard testing usu­ally fail to identify the cause of such health prob­lems. Sometimes it is suggested that the patient is a hypochondriac or in need of psychiatric evalu­ation. When asked if there might be a connection between the symptoms and formaldehyde, most physicians either do not know or believe that formaldehyde merely causes irritation. As a result, the patient’s health continues to deteriorate from continued exposure.

a. Jack Thrasher and Alan Broughton. The Poison­ing of Our Homes and Workplaces: The Indoor Form­aldehyde Crisis. Seadora. 1989, pp. 50-72.

but we do not recommend this practice. The byproducts of combustion generated by this machinery are readily absorbed into the plas­ter and other building materials. The heaters also create an unhealthy environment for the workers exposed to their fumes. Electric heat­ers tend to be more expensive to run, with far less BTU output. We recommend a combi­nation of dehumidifiers when necessary and careful scheduling so that the plasterwork is done during a warm, dry period. Although heat may be required for the comfort of the construction team, it is far less significant than dehumidification to the proper drying of wet building materials. In summary, we suggest that the following instructions be included in your specifications:

• Plaster shall be free of additives.

• The use of gas – or kerosene-generated heaters within the building envelope is prohibited.

• Turbo high-velocity heaters, other elec­tric heaters, and blow-in heaters with combustion sources outside the building envelope are acceptable for adding heat to a building during cold-weather con­struction.

• If plaster is applied when weather condi­tions do not permit the building to re­main open and well-ventilated, electric dehumidification should be used. At tem­peratures under 70 degrees Fahrenheit, moisture levels should be maintained at approximately 45 percent relative air hu­midity using electric dehumidification until the building is dry enough to consis­tently maintain this range without the use of this equipment. Interior surface tem­peratures shall remain above 50 degrees. Refrigerant dehumidifiers may not work well when temperatures drop below 65 de­grees Fahrenheit.

Introduction

Finishes include all surface materials and treatments in the home. They are what is seen on a daily basis and, along with furnishings, constitute the personal signature of the owner. Finishes are the predominant source of odors in a new home. They can introduce a multi­tude of toxic volatile organic compounds into the air and will continue to volatilize, or out – gas, for years after the home is completed. However, when chosen carefully, finishes can enhance health and well-being as well as add to the aesthetic value of the home.

Until recently, nonpolluting finishing products were considered specialty items. Fortunately, healthier products are now regu­larly appearing on the market. Many of these are easily accessible, cost competitive, and comparable in performance to their more toxic counterparts. Some even have the ability to improve air quality by sealing in toxins that may be present in underlying materials.

In some regions, traditional nontoxic fin­ish materials are readily available and widely used. In the Southwest, for example, tile, stone, natural wood, and plaster are commonplace, whereas in many regions of the country they have been replaced even in custom homes by wall-to-wall carpeting, vinyl wall coatings, laminate cabinetry, and other synthetic sub­stitutes. When you build a healthy home, we encourage you to take full advantage of the traditional materials native to your region.

Plaster

Plaster generally provides a healthful interior wall finish. Because of the labor and skill in­volved in its application it is a more expensive finish, but it is much sought after for its beauty. Plaster has the ability to block the small amount of VOCs present in the gypsum lath and taped joints that it covers in frame con­struction. Although this dense material works well as an air barrier, plaster will develop gaps due to shrinkage and on occasion will develop

CASE STUDY 9.1

Moisture Problems Associated with Windows

By far the biggest health concern involving windows occurs when they fail to do their job properly. This job is to let in natural light and allow for ventilation while keeping water out. Windows have drainage channels that are de­signed to shed water away from the building, but if these are not working properly they can channel water into the building cavity, causing serious water damage.

A simple testing procedure can determine if the windows themselves are shedding water properly (see Division 13 for window testing). Windows can be faulty because of manufac­turing defects, mishandling during transport, or improper installation. Windows have a structural weak point where the sill is screwed into the jamb. The seal can break during han­dling and the tiny gaps can go undetected. Some window manufacturers have added a neoprene gasket at this juncture to make it more secure. If the juncture between the win­dow and the wall contains gaps resulting from incomplete or incorrect application of sealing, air will travel through the gaps. When that air sheds moisture because of temperature differ­entials, condensation can accumulate. Proper sealing is discussed in the section on insula­tion around doors and windows in Division 7.

Improper head, jamb, and sill flashing can also result in water finding its way into the wall cavity. (For appropriate flashing materials, see the section in Division 7 on water manage­ment at doors and windows.) These water in­trusions, which are not readily detectable in the completed building, can eventually lead to structural deterioration and mold problems. In the section on testing for weathertightness in Division 13, we discuss a test that can help determine if there are any installation faults that can lead to future water damage. This test can be performed at a time in the construction when faults can still be easily and inexpen­sively corrected. All of these potential prob­lems related to windows are exacerbated if the wall cavity does not have a means of drying out once it gets wet.

Because the quality control testing proce­dures we have referred to are not standard for most residential construction companies, it is unlikely they will be performed unless you specify them in your construction documents. These measures will take a little extra time but can potentially extend the life of a building for many years and prevent mold problems that could be devastating to your health.

Wood Window Frames

Wood windows are routinely dipped in a wa­terborne fungicide. Unlike wood doors, it can be cost prohibitive to have operable windows custom made. Chemically sensitive individu­als will often choose steel or aluminum win­dows with a baked-on enamel finish to avoid exposure to the fungicide as well as to the ter – penes from pine frames. Wood windows can be sealed to avoid these exposures. You may wish to specify the following: [14] [15]

the section on clear vapor-barrier sealants for wood in Division 9.

• Where a painted finish is scheduled, use a primer paint that seals in VOCs, as specified in the section on paints in Division 9.

Most wood window manufacturers also pro­duce clad windows, which have wood on the inside and aluminum, steel, or fiberglass coat­ing on the outside for weather protection. The cladding provides UV protection so that it is unnecessary to apply protective coatings on the window exterior. If unclad windows are used, you will need to do yearly maintenance consisting of staining and sealing in order to protect the window frames from the elements.

The following products do not contain many of the toxic substances commonly found in exterior wood finishing products and can be used for the preservation of wood window frames and doors:

• AFM Safecoat DuroStain: Wood stain

• Auro Natural Wood Stain No. 160: Color­less and color finish, good weather resis­tance

• BioShield Aqua Resin Stain: Weather – resistant wood finish with ultraviolet pro­tection

• BioShield Primer Oil #1: Undercoat; use finish coat of Livos Kaldet Stain or Livos Vindo Enamel Paint

• OS Color One Coat Only: Weather – and UV-resistant, water-repellent, semitrans­parent wood stains

• Weather Pro: Water-based, water-repel­lent wood stain

Weatherstripping

Weatherstripping is used around doors to make them airtight and resistant to water leak­age. Weatherstripping can also be specified around interior doors where noise or odor control is desired. Most available weatherstrips are made of synthetics, including silicone, ure­thane foam, polypropylene nylon, and neo­prene. Some will outgas. Neoprene, for exam­ple, can have a strong odor. Brass and stainless steel weatherstripping are available at many hardware stores. Choose the least odorous weatherstripping that accomplishes the job.

As mentioned earlier, when planning a healthy home the garage and mechanical room should be designed so they do not open directly to the interior because they will in­troduce harmful byproducts of combustion and odors into the home. A simple breeze­way can provide weather protection between a detached garage and the home. However, doors and common walls between home and garage are found in almost all new housing be­cause many people find a detached garage to be an unacceptable inconvenience. Where a door to the garage or mechanical room opens into the living space, it is important to spec­ify that these doors have a threshold sealed with an acceptable sealant. The doors should be fully weatherstripped to prevent harmful fumes from entering the living space through the door openings. In fact, the entire com­mon wall between the home and the garage should be made airtight so that fumes do not seep through the wall from the garage into the home. For the specifics on creating this air­tight wall, refer to Division 9.

Windows and sliding glass doors generally come with removable screens. Screens for french doors or glass swinging doors usually are not provided by the manufacturer and must be custom made. Aluminum screening was standard in the past but has been almost
completely replaced with fiberglass or nylon mesh. These materials are more flexible, more transparent, do not dent, and are easy to re­place. Unfortunately, they also can be odor­ous, especially if they have been treated with insect repellents, pesticides, or other chemi­cals. When windows arrive onsite the screens should be unwrapped and stacked in a pro­tected environment so they have an oppor­tunity to air out prior to installation in the completed home. If after a substantial airing the screens still have an objectionable odor, they can be replaced with aluminum or cop­per at a custom screening company. Ander­sen windows are available with aluminum or stainless steel insect screens. Marvin windows can be ordered with aluminum screening.

Screens on crank-out casement or awning windows will have more impact on indoor air quality because they are placed on the in­side of the glass. Occupants will be exposed
to these screens even when the windows are closed. On double-hung windows, the screens are placed outside the glass.

Wood Doors

Standard Manufactured Doors

Wood doors, both solid and paneled, are typi­cally treated with biocides and manufactured with toxic glues. Paneled wood doors use less glue than solid veneered doors and will there­fore outgas less. The face veneer used on flush wood doors is luan, a mahogany commonly imported from the Philippines or Thailand, where it is obtained using forestry practices that damage the environment. Interior fire­rated doors and hollow-core doors often contain a particleboard center that will con­tinuously outgas formaldehyde fumes. Stan­dard manufactured doors should be sealed to lock in harmful vapors. We recommended the following specifications when using standard manufactured doors: [12] [13]

• For a painted finish, prime all six sides with one of the primer paints that seals in VOCs, as listed in Division 9.

Custom Wood Doors

Choosing custom doors allows you to select style, type of wood, and finishes. Some custom door manufacturers will work with you to cre­ate a healthier product by using benign glues and less-toxic shop finishes. You can also pur­chase doors unfinished and have the contrac­tor finish them according to your specifica­tions. Although most custom doors are more expensive, some custom door companies have production or builder lines, which are almost cost competitive with manufactured doors. Paulas chemically sensitive clients who wish to have the warmth and beauty of wood with­out the terpene emissions of pine doors will often order doors made of harder, less odor­ous woods such as maple or poplar. For cus­tom doors, specify the following:

•

Doors shall be glued with a solvent-free glue such as Elmer’s Carpenter’s Glue, Envirotec Health Guard Adhesive #2101, or Titebond Solvent Free Construction Adhesive.

• Doors shall be finished using the speci­fied low-toxic finish (refer to Division 9 for choices) or with an approved shop – applied finish. Submit a dated sample, MSDS, and product literature for owner’s approval of any proposed shop finishes.

Asphalt-based rolled roofing and shingles will outgas when heated by the sun and should be avoided. Clay tile, concrete tile, metal, and slate are all inert, long-lasting slope roof solutions. Wood shingles can be a good roofing material where fire danger is low and humidity is mod­erate and if rot resistant woods such as cedar are used. Zinc or copper strip applied at the ridge will wash wood shingles with preserva­tives every time it rains. Availability of roofing materials varies from region to region.

Roofing Underlayments

In many cases, roofers will want to install an asphalt-based felt paper over the roof sheath­ing. Several non-asphaltic-based underlay – ments are now available to choose from:

• RoofShield: High permeability three – layer spun bond polypropylene underlay – ment

• RooftopGuard: Five-layer polypropylene/ polyethylene underlayment

• StrongSeal Roofing Underlayment: Con­tains no asphalt; both nail-down and self­adhering membranes

• Titanium UDL: Non-asphaltic, coated synthetic roofing underlayment for sloped roofs

Membrane Roofing

Membranes for flat roofing can be problem­atic. These roofs are in fact more accurately described as having a very low slope, usu­ally Va inch per foot or less. Tile, shingles, and most metal applications that depend on rapid water runoff will not hold up under standing water conditions and are not suitable for low – slope roofs.

Built-up tar and gravel roofing is the most common and least expensive material avail­able for flat roof applications, but we do not recommend it. A tar and gravel roof will emit volatile organic compounds from asphalt, benzene, polycarbon aromatics, toluene, and xylene. It will continually outgas when heated by the sun. Some of these vapors will inevi­tably find their way into the living space and degrade air quality Eventually the roof will
outgas to the point where it does not adversely affect indoor air quality, but soon thereafter it will require replacement. The average tar and gravel roof is guaranteed for only two to five years and may require replacement in less than 10 years. Since most people are not in a position to move out for several weeks when their roof is repaired or replaced, they will be exposed to high levels of toxic fumes. Chemi­cally sensitive individuals often have difficulty tolerating a tar and gravel roof that is less than one to two years old.

Toxicity is not the only health concern to consider when choosing a product. Many per­sistent mold infestations begin with an unde­tected roof leak. No type of roofing installation is foolproof, but the use of high quality roofing materials and skilled installers will reduce the risk of leakage.

Although other solutions are typically more expensive than tar and gravel, you must carefully weigh both lifecycle and health costs when making a roofing choice. Single-ply membranes such as Brai Roof contain asphalt and will also outgas to a certain extent during application when heat is applied to fuse the membrane. Once installed, they are fairly sta­ble. These roofs also carry a longer warranty. Brai Roof can be applied in two ways. It can be mechanically fastened, with seams heat welded together. This is the less odorous method and the one we recommend. It can also be glued down with a layer of hot-mopped tar and seams can be sealed with hot tar. We do not recom­mend this technique. Certain single-ply mem­branes can be repaired by welding patches onto the existing roof, thereby extending the roof s life for many years. There are also roll-on roof­

ing products that do not require roofing con­tractors for application or repair.

It is especially important with roofing ma­terials that the manufacturer s instructions for installation and the warranty criteria be care­fully followed. Here are some more benign alternatives to tar and gravel roofing for flat – roof applications:

• AFM Safecoat Dynoflex: Low-toxic roof coating to replace tar and gravel that can be walked on and remains flexible

• Brai Roof: An asphaltic-based single-ply membrane (specify mechanical fastening and torch-down application)

• Mirrorseal: A single-ply, fluid-applied roofing system

• Resource Conservation Technologies, Inc.: An acrylic polymer paint or roll-on system that uses titanium dioxide with
propylene glycol and contains no toxic dis­persants or tints

• Stevens EP: A heat weldable, scrim rein­forced, single-ply roofing membrane made of ethylene propylene

Joint Sealants

Many solvent-based caulking compounds are formulated with hazardous solvents such as acetone, methyl ethyl acetone, toluene, and xylene. They are toxic to handle and may out – gas for extended periods of time. The follow­ing are suggested options for exterior use:

• loo percent silicone aquarium-grade caulk of any brand. Aquarium-grade does not contain any additives that will harm fish and therefore will be safer for humans as well. Be sure to read content labels because some are labeled ‘pure silicone’ but con­tain other ingredients.

• AFM Safecoat Caulking Compound: Water-based elastic emulsion.

• DAP: loo percent Silicone Sealant or Sili­cone Plus.

• GE Silicone II: Silicone sealant formu­lated for different types of application; some may contain biocides.

• Lithoseal Building Caulk: Urethane mod­ified polymer, inert once cured.

• Phenoseal Surpass Caulk and Sealant, Valve Seal, Vinyl Adhesive Caulk: Line of water-based sealants and caulks.

• Weatherall UV Guard Premium Caulk­ing: A professional strength acrylic-based sealant designed for use in a wide variety of construction applications.

Further Reading

Lafavore, Michael. Radon: The Invisible Threat. Rodale Press, 1987.

Lstiburek, Joseph. Builders Guides. Available

through The Energy & Environmental Building Association, 10740 Lyndale Avenue South, Suite 10W, Bloomington, MN 55420,952-881-1098, eeba. org. A series of climate-based field guides with explanations, details, and techniques to effectively implement energy – and resource – efficient residential construction

Lstiburek, Joseph and John Carmody. Moisture Con­trol Handbook: Principles and Practices for Resi­dential and Small Commercial Buildings. Van Nostrand Reinhold, 1993.

US Environmental Protection Agency. A Citizens Guide to Radon. 2nd ed., US Government Print­ing Office, ЕРА 402-K-92-001, May 1992.

US Environmental Protection Agency. Consum­ers Guide to Radon Reduction. US Government Printing Office, ЕРА 402-K-92-003, May 1992.

US Environmental Protection Agency. Indoor Ra­don and Radon Decay Reduction Measurement Device Protocols. US Government Printing Of­fice, EPA 402-R-92-004, July 1992.

US Environmental Protection Agency. Model Stan­dards and Techniques for Control of Radon in New Residential Buildings. US Government Printing Office, EPA 402-R-94-009, March 1994.

US Environmental Protection Agency. Radon Con­tractor Proficiency (RCP) Program. US Gov­ernment Printing Office, ЕРА 402-B-94-002, September 1994.

A well-sloped roof with a sizable overhang is preferable to a flat or low-sloped roof for the following reasons:

The roof overhang plays an important role in protecting the walls and foundation from water damage by directing water away from the building.

Inert roofing materials are readily avail­able and are standard products for sloped – roof construction, while they are an exception in flat or low-sloped residential roof construc­tion.

Sloped roofs shed water quickly, whereas water will puddle and linger on poorly con­structed flat roofs.

Flat roofs have a higher failure rate and shorter life expectancy, which may lead to devastating mold problems.

Overhangs can be sized to suit the solar conditions in your region, providing shade in the summer while allowing maximum heat entry in the winter.