The National Association of Home Builders (NAHB) has released a white paper about mold in response to the increase in litigation against builders, building owners and property managers. National media attention has led to a number of web sites which they feel has led to conflicting information about the impacts of exposure to health and the proper methods of remediating mold.
The white paper is intended to provide and "overview of some of the mold issues and to alleviate undue concern about mold in indoor environments."
Although there is conflicting information on the web and in the literature, the NAHB states that there are two issues that experts agree upon. They are that active mold growth should be removed and that you must eliminate excessive moisture to stop the growth.
National press attention to lawsuits and health studies has focused on one type of greenish black mold called Stachybotrys chartarum, commonly referred to as "toxic mold." The NAHB states that molds can grow on cloth, carpet, leather, wood, wallboard, household dust, and on anything that is made of organic material. A sustained growth of mold requires moisture, organic material such as those listed as a food source and temperatures in the range of 40° to 100°Farenheit.
Mycotoxin, a toxic substance, can be found in the spores and create a strong odor commonly referred to as a "musty" smell. Early detection and prompt treatment of excessive moisture is the best prevention. The musty smell is an indicator of a moisture problem as well as presence of discoloration and mold on surfaces.
The NAHB recommends these steps to help minimize mold growth.
- Take notice of musty odors in the home because they indicate the presence of mold. Look for visible signs of mold and abate the moisture source.
- Watch for condensation and wet spots and eliminate sources of moisture.
- Prevent moisture resulting from condensation by increasing surface temperatures or reducing moisture levels in the air. To increase the surface temperature, insulate or increase the circulation of heated air. To reduce moisture levels in the air, repair leaks, increase ventilation (if outside air is cold and dry), or dehumidify.
- Perform building and HVAC inspections and maintenance. Repair the condensate drain if the air conditioning system's drip pan overflows with water.
- Vent clothes dryers to the outdoors.
- Run the air conditioner and/or a dehumidifier during the humid months of the year. Controlling indoor air moisture to below 65 percent relative humidity will limit the probability of supporting mold growth.
- Keep the relative humidity as low as is comfortable during the winter season for houses in cold climates. Mold growth on interior surfaces of exterior walls can occur during the heating season. The combination of cool surfaces and excessive humidity can cause a high near-surface relative humidity and condensation. Experience has shown that an air moisture level below 40 percent relative humidity during the heating season will prevent condensation on surfaces. This level of humidity may not be appropriate for houses in severe cold climates. A sign of excessive humidity is condensation on the inside of windows. If condensation is present for prolonged periods take steps to reduce the moisture source or increase ventilation.
- Clean and dry any wet or damp areas within 48 hours.
- Provide drainage for roof rainwater and maintain the ground with a slope that drains water away from the foundation.
- Repair water leaks in the building envelope as soon as possible.
- Do not store organic materials such as paper, books, clothes, etc., in humid locations (such as in unconditioned basements).
- Exercise extra care when cleaning up after water damage from flood and sewer water.
- Consider the use of dehumidifiers in areas such as unconditioned basements.
The white paper provides information about mold abatement and remediation, the current state of mold sampling and testing, and possible health effects of mold exposure.
Pat Rioux
