Mold: Chapter 2 - Detection and Prevention

5/19/2017 (Permalink)

mold prevention and detection, mold testing

How to prevent mold growth

The key to preventing and stopping indoor mold growth is to control excessive moisture and condensation. Keeping susceptible areas in the home clean and dry is critical. In general, mold will not grow indoors without water, dampness or excessive moisture.

Three main factors contribute to condensation of water on building surfaces:

• Relative Humidity: Condensation occurs when the air is saturated with water and it cannot hold any more moisture. For example, steam generated from bathroom showers or from cooking can fill up the air with moisture, which will then condense into drops of water on cooler surfaces, such as mirrors and windows. Where possible, localized sources of humidity, such as clothes dryers, should be directly vented to the outdoors.  To lower indoor humidity during warm, humid weather, air conditioners and/or dehumidifiers should be used. In chronically damp areas such as basements or crawlspaces, it is often recommended that dehumidifiers be used to maintain humidity levels below 60 percent.

• Temperature: Warm air holds more moisture than cold air. Condensation occurs when warm humid air comes into contact with a cold surface and the moisture condenses into water. This can often be seen on single-pane windows, where water condenses and then runs down, causing the wood frames and sills to rot and the wall under the windows to blister. Condensation can occur on exterior walls, particularly north-facing walls, if they are not properly insulated. Other chronically cold surfaces, such as cold water pipes, should be covered with insulation to help prevent condensation.

• Poor Ventilation: Indoor humidity can build up if there is not enough ventilation and exchange of indoor and outdoor air. Where there is little or no air movement, such as behind dressers and cabinets, surfaces can remain cooler than surrounding areas, which can lead to increased condensation and mold growth. It is recommended that the area be ventilated and the occupants use exhaust fans (vented to the outdoors) to remove moisture from high-humidity areas, particularly in bathrooms, kitchens and laundry areas. Furniture should be moved slightly away from walls so that air can freely pass behind it. Air should be allowed to circulate between rooms and regularly ventilate to remove humid air. Fans should be used as needed.

Other things that can be done are to clean and repair gutters regularly, make sure the ground slopes down and away from the home’s foundation and keep air conditioner drip pans and drain lines clean. In addition, in air conditioned buildings in hot and humid climates, vinyl wall coverings on the interior sides of exterior walls should not be used, as these materials can trap moisture, resulting in mold growth underneath them.

In the case of floods or leaking pipes, any standing water should be promptly removed and water-damaged materials should either be dried out and cleaned, or removed and replaced. Porous materials that are wet for more than 48 hours are likely to produce mold growth and should be discarded. In instances where the water damage is extensive, it is recommended that professional help, such as a commercial restoration company, be consulted.

Should I test my home for mold on a routine basis?

Probably not. Looking for evidence of water damage and visible mold growth should be your first step. Testing for mold is expensive, and you should have a clear reason for doing so. In addition, there are no standards for “acceptable” levels of mold in the indoor environment. When air testing is done, it is usually to compare the levels and types of mold spores found inside the home with those found outdoors. If you know you have a mold problem, it is more important to spend time and resources solving the moisture problem and getting rid of the mold than to spend it on sampling.

What to do if you see or smell mold in your home

The most important step is to identify the source(s) of moisture, which result in mold growth, and make repairs to stop them. If you only clean up the mold and do not fix the moisture problem, most likely the mold growth will recur.

If the source of the moisture is related to a building failure or fault, such as a burst pipe or leaking roof, a professional contractor should be consulted. In instances where the moisture source does not appear to be related to leaks, floods, structural faults or rising damp, it is most likely due to condensation. If you do not see mold growth but smell a musty odor, mold may be growing underneath or behind water-damaged materials, such as walls, carpeting, or wallpaper.

Once the source of the moisture has been identified and fixed, you need to decide if removing the mold from the affected areas is something that can be done without professional assistance. If the mold growth was caused by sewage back-up or other contaminated water, potential pathogens may be present and the work should be performed by a professional contractor that has experience in cleaning buildings damaged by contaminated water.

If the mold growth is due to condensation or small-scale leak and is limited to a small area (fewer than ten square feet), you can probably do the work yourself following guidelines such as those that have been prepared by the U.S. Environmental Protection Agency (EPA), Canada Mortgage and Housing Corporation and AIHA.

On hard surfaces, such as countertops and furniture, use detergent and water to wash mold off and then dry completely. The use of biocides or chemical disinfectants is not recommended as these may be hazardous to occupants.

Moldy porous or absorbent materials, such as ceiling tiles, wallboard and carpeting should be removed and replaced. People cleaning mold should wear rubber gloves, goggles and an approved respirator to protect against breathing airborne spores. An N95 respirator would be appropriate for most cleanup projects, provided that you are medically capable of wearing a respirator. If you have health concerns, you should consult your doctor before doing any mold cleanup.

Over the past decade or so, the industry has given rise to many individuals and companies who tout themselves as experts and certified in various aspects of mold investigation and remediation, but who may have little or no practical experience. If you choose to hire a consultants to help identify your problem, or a contractors to perform the cleanup in your home, make sure that they have specific work experience in dealing with and cleaning up mold, and check their references.

Source: AIHA American Industrial Hygiene Association

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