Clean It - Dry It - Disinfect It:
Mold and Mildew Control

By Jane K. Frobose
Colorado State University Extension
Denver County, Feb. 2008

While we tend to think of Colorado as being a dry, semi-arid environment, many homes can still become moist breeding grounds for molds and mildew, which can cause a host of responses ranging from allergies, infections, and asthma, to chronic respiratory illness. Tightly sealed homes constructed in the past few decades to reduce drafts have helped to decrease the use of fossil fuels, but now homes aren’t drying out as fast as they used to, either, because they are so “tight” and well insulated. Since molds grow most quickly in damp, warm, poorly ventilated areas, minimizing or eliminating these conditions in your home can keep mold growth to a minimum. Be aware that mold may be present and may be a health risk for your family, if your home has water damage due to:

  • Flooding,
  • Sewage back-up,
  • Plumbing or roof leaks,
  • Damp basements or crawl space,
  • Overflows from sinks or bathtub, or
  • High humidity: steam cooking, dryer vents, humidifiers.

Generally, mold is most likely to be found where moisture or relative humidity levels are high (greater than 55%.) Excess moisture in a home can come from less obvious sources such as moisture from the earth that migrates through concrete walls or the foundation floor, to more obvious sources such as a utility back-up or a leaky pipe. Normal day-to-day activities like bathing and cooking also place large amounts of moisture into a home’s interior. To reduce indoor humidity, the most effective thing you can do is to regularly vent bathrooms, kitchens, dryers and other moisture-generating sources to the outside. It is also important to correct plumbing and roof problems quickly, as well as making sure that water is properly draining away from the home’s foundation at all times of the year.

Clean it. Dry it. Disinfect it.

If you find mold growing in your home, affected areas or items should be treated to remove mold spores as soon as possible:

  • One of the most effective and least expensive disinfectants for hard surfaces is chlorine bleach. Use only bleach with 5.25 percent sodium hypochlorite. Follow directions on the label or use a solution of one-half to three-fourths cup bleach to one gallon of water. To kill mold, keep the solution on the affected area for 10 to 15 minutes. When cleaning with a chlorine bleach solution, wear rubber gloves to protect your skin. Keep the solution away from eyes and skin and avoid prolonged breathing of vapors. NEVER mix bleach with ammonia or other household cleansers containing ammonia. Before disinfecting, clean hard surfaces thoroughly with a detergent solution.
  • Spores from mold and mildew can be dangerous to your health. Wear a respirator or dust mask if you are sensitive to mold and mildew when working with items that smell musty or are filled with mold.
  • Launder washable items with detergent and chlorine bleach, if safe for the fabric. Do not dry until the entire stain is removed or it may become “heat-set” in the fabric.
  • Take non-washables to the dry cleaners, and be sure to point out the mold stain for best dry cleaning results.

How to Deal With a Home Flood

If you are suddenly confronted with a large amount of water flooding an area of your home, act quickly since it only takes 24-48 hours for mold to germinate and grow.

  • Quickly remove and begin drying as many items as possible -- furniture, carpeting, stored boxes, etc.
  • Mop up and remove as much water as you can and/or call in a carpet cleaning or mold mitigation professional who has equipment suited for large scale water removal and sanitization.
  • Use a disinfectant or light chlorine bleach solution to scrub walls and floor.
  • Use large fans and dehumidifiers to circulate air and dry a wet area quickly and thoroughly. If outdoor air is dry, leave windows open to promote drying.
  • Absorbent materials such as ceiling tiles, carpet, carpet padding, and upholstered furniture or soaked mattresses that become moldy may have to be replaced.

The following resources are also available for additional information related to mold and mildew clean-up:

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Updated Tuesday, July 22, 2014