What Rural Developers Need to Know

by Jack Anderson
Rural Voices - The Magazine of the Housing Assistance Council
Fall/Winter 2002 - Volume 7/Number 4

Rural developers engaged in the rehabilitation of older homes and the construction of new homes have an ideal opportunity to create healthier housing for their clients. Experts are just beginning to realize the importance of housing conditions to residents' health. Over the last decade, child asthma cases have doubled in the United States, and many researchers estimate that these cases are associated with exposures to allergens in the home. Mold, pests, pets, dust, cold air, and dry heat can all trigger asthma. When these conditions are present, a child is more likely to experience an allergic reaction. Therefore, any efforts to reduce or eliminate these exposure sources can also reduce the potential for childhood asthma.

Rural developers engaged in the rehabilitation of older homes and the construction of new homes have an ideal opportunity to create healthier housing for their clients. By making simple and cost-effective modifications to current renovation practices and adopting new construction techniques, developers can minimize or eliminate exposure to sources that may lead to respiratory distress, including asthma. These practices and techniques can also help achieve energy efficiency. Important techniques for achieving healthier housing include minimizing moisture, promoting adequate ventilation, properly exhausting combustion appliances, eliminating entry points for pests, and providing smooth, easily cleanable surfaces.

Renovating and Remodeling Older Housing

Whether a developer is performing gut rehab or undertaking more modest housing code repairs, there are a number of measures that can contribute appreciably to a healthier residential environment, while adding minimal cost to the overall project.

First, every effort should be made to reduce or eliminate sources of moisture or water infiltration, which can cause mold. Leaky plumbing fixtures and pipes need to be repaired or replaced. If an older roof is not being replaced, it must be patched to stop leaks. Any water or moisture-damaged plaster, drywall, insulation, or other substrates that cannot be thoroughly dried should be replaced to eliminate the possibility of mold growth. Gutters, downspouts, leaders, and splash blocks must all be functional so that rainwater is directed outward from the structure. If needed, re-grading of the surrounding soil may be necessary to assure that the ground slopes away from the foundation, thereby limiting the potential for water absorption through foundation walls.

New bathtub and shower enclosures should be built using non-absorbent materials that resist moisture and provide a good air barrier. Paper-faced gypsum board should be avoided. If not being replaced, bathtubs and showers should be re-caulked with a high quality silicone sealant.

Damp basements should not be occupied as living spaces unless moisture has been controlled or eliminated. A dehumidifier may be necessary to remove excess dampness due to the reaction of cooler moist masonry floor and wall surfaces with the warmer surrounding air. It may not be advisable to install carpeting in basements since it can serve as a breeding source for mold. Carpeting should also be avoided in bathrooms and kitchens, where wetness is normally anticipated.

Crawl spaces with dirt floors are a source of moisture infiltration for a home. Therefore, a vapor barrier, such as heavy-duty polyethylene plastic sheeting, should be installed over the bare soil and a minimum of one foot up perimeter walls.

Controlling the flow of warm air into attic spaces is important, particularly during winter months when condensation can form due to cool and warm air mixing. This condensation, coupled with insulating materials, can generate mold. Holes and bypasses into the attic should be properly sealed or closed off to prevent this warm airflow. Also, for homes in warmer climates, attic vents should be installed both high and low near the ridge board and the soffits. This, too, will help eliminate moisture and mold growth in the attic.

Exhaust fans should be installed in bathrooms and kitchens and vented to the exterior, thereby reducing interior moisture in these rooms and the potential for mold. Dryers should also be vented to the exterior because of the moisture generated during drying cycles.

Second, to eliminate the possibility of carbon monoxide poisoning, combustion appliances must be properly exhausted to the exterior. In the case of furnaces and water heaters, a trained professional should test the units to make certain that there are no interior exhaust leaks and that the units are functioning efficiently. Carbon monoxide detectors should be installed near these appliances and in the primary living space, particularly near where bedrooms are located.

When gas stoves and ovens are used for cooking, a power vented fan or range hood should be installed and exhausted to the exterior. This will reduce the potential for carbon monoxide poisoning from an improperly operating stove or oven.

Third, to control entry of rodents and birds, corrosion-proof materials should be installed that close or seal off holes and small openings on the exterior. Exhaust vents should be covered with mesh screen to prevent animal entry yet allow for proper venting of appliances or fans.

In terms of pests, such as cockroaches, removing potential food sources is key. Although residents are typically responsible for storing food in closed containers and properly disposing of garbage as far away from the unit as possible, steps can be taken to seal entry points to limit pest access. For example, a silicone sealant can be applied between gaps in baseboard moldings and floors and wall surfaces.

Fourth, although residents typically prefer carpeting, smooth and easily cleanable floor surfaces, such as vinyl sheet goods, tile, wood, and wood laminates, make it simpler to remove dust. Carpeting, even in areas not normally subjected to wetness, can serve as a reservoir for moisture, mold and dust mites. Therefore, providing smooth floors limits a potential exposure source of allergens and enables residents to more effectively clean to further reduce allergens.

New Construction

Most of the suggested modifications to current housing rehabilitation practices also apply to new construction. Additional techniques can further limit asthma allergen sources when building new housing units.

In homes with forced-air heating and cooling systems, return ductwork should be sealed to limit negative air pressures that pull in contaminants from exterior sources. Additionally, ductwork in spaces that are unconditioned should be insulated to limit potential moisture and mold development and pest infiltration. Ductwork should not be installed in attics, crawlspaces, or garages, whenever possible.

Cold-water plumbing lines should be insulated with foam pipe insulation to limit condensation in warmer climates. Lever-type shut-off valves should be installed for washing machine hook-ups and water heaters to minimize any water damage in the event of a hose break or other failure.

When installing exterior siding over house wrap, such as Tyvek, drainage planes should be created too so that rainwater is shed away from the siding and wrap. New windows and exterior doors should have pan flashings to direct rainwater away from wall cavities. Again, eliminating potential moisture sources reduces the likelihood of mold growth.

Summary

These suggestions are by no means comprehensive. But by making these simple, relatively inexpensive modifications to housing renovation and new construction practices, rural developers can help limit residential exposures to asthma-producing allergens.

Additional resources and information are available from the following organizations to help rural developers create healthier residential environments:

Information for this article was obtained from "Remodeling Guidance for Healthy Homes," adopted by the Asthma Regional Council of New England, and various materials written by Building Science Corporation and Ellen Tohn of ERT Associates.  The author is indebted to these organizations.