Controlling Mold Growth: It's All About Moisture Control

Because mold can grow on many different types of materials, it is essential to maintain effective moisture control within a building. The fact that molds need moisture to colonize a surface means that preventing excess moisture in a building usually will prevent mold from growing. Once mold has established itself as a colony, it often can survive in much less moisture than was required to establish the colony. Additionally, the reintroduction of even a slight amount of moisture into an environment where an inactive mold colony exists can trigger new growth of the colony.

Moisture can enter a home through many different means, such as pipe leaks, roof leaks, high ground water and condensation. In addition, many daily activities can produce moisture. Some of these include cooking, showering and drying clothes. In fact, people themselves produce about three pints of water vapor per day while breathing.

Mold growth in a building can be prevented by practicing effective moisture control procedures. Examples of moisture control methods include:

  1. Fix broken pipes as soon as they are discovered and promptly clean all impacted areas.
  2. Repair leaky roofs as soon as the problem is found and promptly clean all affected areas.
  3. Use exhaust fans in kitchens and bathrooms while showering or cooking to remove the humidity that these activities produce.
  4. Vent clothes dryers to the outside.
  5. Put clothes away in closets or drawers only after they are completely dry.
  6. Leave closet doors open to allow air circulation.
  7. Do not place objects too close to cool walls (such as exterior walls) as this may create a barrier that prevents air and heat circulation and increases the likelihood of condensation on the wall surface.
  8. Use dehumidifiers to remove moisture from areas with high humidity when ventilation is not an option (such as when the air being used to ventilate is of higher moisture content than the air being replaced).
  9. Install energy-efficient windows to reduce window condensation.
  10. Utilize drain tile and a sump pump to control ground water.
  11. Landscape the area surrounding a building so that moisture is carried away from the building.
  12. Ensure that rain gutters are clear of debris and as leak free as practical.
  13. Extend rain gutter downspouts so they do not dump water right next to the building.
  14. Keep sprinklers from hitting a building (especially open windows).

Take a look at the following papers for a more thorough look at indoor moisture problems:

Other Indoor Air Quality Web Resources - Controlling Mold

Contact Information

  • Justin Otto - North Dakota Department of Health
  • Electronic mail address:
  • Office phone: 701.328.5188

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Page last revised: January 22, 2015