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Mold, Moisture and Your Home
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Mold Basics 
Why is mold growing in my home?
 
Molds are part of the natural environment.  Outdoors, molds play a part in nature by breaking down dead organic matter, such as fallen leaves and dead trees.  But indoors, mold growth should be avoided.  Molds reproduce by means of tiny spores; the spores are invisible to the naked eye and float through outdoor and indoor air.  Mold may begin growing indoors when mold spores land on surfaces that are wet.  There are many types of mold, and none of them will grow without water or moisture.
 
Can mold cause health problems?
 

Molds are usually not a problem indoors, unless mold spores land on a wet or damp spot and begin growing.  Molds have the potential to cause health problems.  Molds produce allergens (substances that can cause allergic reactions), irritants and, in some cases, potentially toxic substances (mycotoxins).  Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals.  Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis).  Allergic reactions to mold are common.  They can be immediate or delayed.  Molds can also cause asthma attacks in people with asthma who are allergic to mold.  In addition, mold exposure can irritate the eyes, skin, nose, throat and lungs of both mold-allergic and non-allergic people.  Symptoms other than the allergic and irritant types are not commonly reported as a result of inhaling mold.  Research on mold and health effects is ongoing.  This article provides a brief overview; it does not describe all potential health effects related to mold exposure.  For more detailed information, consult a health professional.  You may also wish to consult your state or local health department.

How do I get rid of mold?  

It is impossible to get rid of all mold and mold spores indoors.  Some mold spores will be found floating through the air and in house dust. Mold spores will not grow if moisture is not present.  Indoor mold growth can and should be prevented or controlled by controlling moisture indoors. If there is mold growth in your home, you must clean up the mold and fix the water problem. If you clean up the mold but don't fix the water problem, then, most likely, the mold problem will recur.
 
Who should do the cleanup?
 
This depends on a number of factors.  One consideration is the size of the mold problem.  If the moldy area is less than about 10 square feet (less than roughly a 3-foot by 3-foot patch), in most cases, you can handle the job yourself, following the guidelines below.  
  • If there has been a lot of water damage, and/or mold growth covers more than 10 square feet, consult with an InterNACHI inspector.
  • If you choose to hire a contractor (or other professional service provider) to do the cleanup, make sure the contractor has experience cleaning up mold.  Check references and ask the contractor to follow the recommendations of the EPA, the guidelines of the American Conference of Governmental Industrial Hygenists (ACGIH), or other guidelines from professional or government organizations.
  • Do not run the HVAC system if you know or suspect that it is contaminated with mold.  This could spread mold throughout the building. 
  • If the water and/or mold damage was caused by sewage or other contaminated water, then call in a professional who has experience cleaning and fixing buildings damaged by contaminated water. 
  • If you have health concerns, consult a health professional before starting cleanup.
Tips and Techniques 
 
The tips and techniques presented in this section will help you clean up your mold problem.  Professional cleaners or remediators may use methods not covered here.  Please note that mold may cause staining and cosmetic damage.  It may not be possible to clean an item so that its original appearance is restored.   
What to Wear When Cleaning Moldy Areas:  
How do I know when the remediation or cleanup is finished?

You must have completely fixed the water or moisture problem before the cleanup or remediation can be considered finished, based on the following guidelines:  


 
 
Moisture and Mold Prevention and Control Tips

Actions that will help to reduce humidity:

Actions that will help prevent condensation:



Testing or Sampling for Mold
 
Is sampling for mold needed?  In most cases, if visible mold growth is present, sampling is unnecessary.  Since no EPA or other federal limits have been set for mold or mold spores, sampling cannot be used to check a building's compliance with federal mold standards.  Surface sampling may be useful to determine if an area has been adequately cleaned or remediated.  Sampling for mold should be conducted by professionals who have specific experience in designing  mold sampling protocols, sampling methods, and interpreting results.  Sample analysis should follow analytical methods recommended by the American Industrial Hygiene Association (AIHA), the American Conference of Governmental Industrial Hygienists (ACGIH), or other professional organizations.
 
Suspicion of Hidden Mold 
 
You may suspect hidden mold if a building smells moldy but you cannot see the source, or if you know there has been water damage and residents are reporting health problems. Mold may be hidden in places such as the backside of dry wall, wallpaper or paneling, the top-side of ceiling tiles, or the underside of carpets and pads, etc. Other possible locations of hidden mold include areas inside walls around pipes (with leaking or condensing pipes), the surface of walls behind furniture (where condensation forms), inside ductwork, and in roof materials above ceiling tiles (due to roof leaks or insufficient insulation).
 
Investigating Hidden Mold Problems 
 
Investigating hidden mold problems may be difficult and will require caution when the investigation involves disturbing potential sites of mold growth. For example, removal of wallpaper can lead to a massive release of spores if there is mold growing on the underside of the paper. If you believe that you may have a hidden mold problem, consider hiring an experienced professional.
 
Cleanup and Biocides 
 
Biocides are substances that can destroy living organisms. The use of a chemical or biocide that kills organisms such as mold (chlorine bleach, for example) is not recommended as a routine practice during mold cleanup. There may be instances, however, when professional judgment may indicate its use (for example, when immune-compromised individuals are present). In most cases, it is not possible or desirable to sterilize an area; a background level of mold spores will remain, and these spores will not grow if the moisture problem has been resolved. If you choose to use disinfectants or biocides, always ventilate the area and exhaust the air to the outdoors. Never mix chlorine bleach with other cleaning solutions or detergents that contain ammonia because toxic fumes could be produced.   
 
Please note: Dead mold may still cause allergic reactions in some people, so it is not enough to simply kill the mold; it must also be removed.
 
Ten Things You Should Know About Mold
 
 1.  Potential health effects and symptoms associated with mold exposure include allergic reactions, asthma, and other respiratory complaints. 
 
 2.  There is no practical way to eliminate all mold and mold spores in the indoor environment; the way to control indoor mold growth is to control moisture.
 
 3.  If mold is a problem in your home, you must clean up the mold and eliminate sources of moisture.
 
 4.  Fix the source of the water problem or leak to prevent mold growth.
 
 5.  Reduce indoor humidity (to 30% to 60%) to decrease mold growth by: 
a. venting bathrooms, dryers, and other moisture-generating sources to the outside;
b. using air conditioners and de-humidifiers;
c. increasing ventilation; and
d. using exhaust fans whenever cooking, dishwashing, and cleaning.  
 6.  Clean and dry any damp or wet building materials and furnishings within 24 to 48 hours to prevent mold growth.
 
 7.  Clean mold off hard surfaces with water and detergent, and dry completely. Absorbent materials that are moldy (such as carpeting and ceiling tiles) may need to be replaced. 
 
 8.  Prevent condensation.  Reduce the potential for condensation on cold surfaces (i.e., windows, piping, exterior walls, roof and floors) by adding insulation. 
 
 9.  In areas where there is a perpetual moisture problem, do not install carpeting.
 
10.  Molds can be found almost anywhere; they can grow on virtually any substance, provided moisture is present. There are molds that can grow on wood, paper, carpet, and foods.