Mold Prevention

Controlling moisture is the key to preventing indoor mold growth. The relative humidity of indoor environments should be maintained at 20% - 40% in winter and no more than 60% the rest of the year.


Since moisture control is the key to mold control, when water leaks or spills occur indoor, take action immediately. If wet or damp materials or areas are dried 24 hours - 48 hours after a leak or spill happens, you can avoid giving mold a chance to grow.

What else can you do to prevent mold? You can:

  1. Clean and repair roof gutters regularly. This can prevent water collecting by your home and create a source of moisture for mold.
  2. Make sure the ground slopes away from the building foundation, so that water does not enter or collect around the foundation. Again, you are preventing a potential source of moisture from developing.
  3. Keep air-conditioning drip pans clean and the drain lines unobstructed and flowing properly. The last place you want mold to be growing is in your air-conditioning unit. Otherwise, you will be cooling your indoor air and blowing mold spores throughout your home.
  4. Keep indoor humidity low. Ideally, relative humidity should be between 30 percent and 50 percent, even in summer. Relative humidity can be measured with a moisture or humidity meter. This small instrument is available at many hardware stores.
  5. If you see condensation or moisture collecting on windows, walls or pipes, act quickly to dry the wet surface and reduce the moisture / water source. Remember that condensation can be a sign of high humidity. It could be a sign that you should get a humidity meter and test your home.
  6. Vent appliances that produce moisture, such as clothes dryers, stoves and kerosene heaters to the outside. This eliminates a large number of potential sources of humidity in your home.
  7. Use air conditioners and/or de-humidifiers when needed.
  8. Run the bathroom fan or open the window when showering. Use exhaust fans or open windows whenever cooking, running the dishwasher or dishwashing, etc. Here, the intent is to stop condensation from forming, and providing another moisture source.
  9. Increase ventilation or air movement by opening doors and/or windows, when practical. This also helps to reduce condensation. Make use of fans as needed.
  10. Cover cold surfaces, such as cold water pipes, with insulation. Again, you prevent condensation and a potential moisture source. Don't underestimate the ability of molds to take up residence based on as little as some condensation.
  11. When practical, increase air temperature. This usually allows more humidity to stay in the air, rather than condensing out on surfaces in your home.
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