Extension Connection

Extension Connection

Prevent Mold Growth in Your Home

Photo of Kathy Sweedler

Kathy Sweedler
Extension Educator, Consumer Economics

Heat plus humidity means "watch out for mold!" Mold can grow on your basement wall, shower door, or even in your refrigerator. If conditions are right, mold can grow in many places in your home. Reducing mold in your home is important for good indoor air quality.

Mold is a microscopic fungus that releases spores into the air. The spores settle on surfaces and grow, sometimes producing a musty smell. Mold can appear as a discoloration of white, orange, green, brown, or black growth. Mildew is a common mold.

Conditions that support mold growth on various surfaces include warm temperatures of 77 to 86 degrees F., moisture or high humidity, and oxygen. Does this sound like your home? It sounds like mine on a summer day. Molds thrive on organic materials such as cotton and wool fibers, paper, leather, and wood, or on surfaces that contain even tiny amounts of food, grease, or soil. Mold growth can deteriorate wood and clothing.

Typical problem areas for mold include the bathroom, laundry room, and basement since they are areas of high humidity. In the basement, condensation from an air conditioner or dehumidifier, leaky pipes, or water standing in sump pump areas can support mold growth. Shower walls in bathrooms are also common areas for mold.

In most cases, it is not practical to test for mold growth in a house. There are no standards for 'acceptable' levels of mold in a dwelling. Plus, reliable sampling for mold can be expensive since it requires special equipment and training. Testing is not generally recommended as a first step.

If mold appears on walls or floors, first clean the surfaces with a detergent. Then mix a solution of ¼ cup chlorine bleach (5.25 percent sodium hypochlorite) with 1 gallon of water to disinfect the area. Do not ever mix ammonia and bleach when cleaning; the fumes are toxic. Allow the solution to stay on the surface for 15 minutes before rinsing with clean water. While cleaning, you may want to wear a mask to filter the mold spores. Use a fan, dehumidifier, and air conditioner to dry the surface quickly. If the outdoor air is dry, a window can be opened to help promote drying. The chlorine/water solution will kill the mold. However, new mold growth will appear on the same surface if the conditions continue to be right for growth.

You can help prevent mold growth by keeping surfaces clean and dry. In humid conditions, use a dehumidifier to dry the air and turn on fans to help with air circulation. Wipe down shower stalls after use and run the exhaust fan in the bathroom for 20 minutes after baths and showers. Use the exhaust fan over the stove when cooking on the stove top. Vent clothes dryers to the outside of the house. Seal cracks in basement walls to keep moisture out.

Moisture control is critical for managing mold. If you had water in your basement as a result of the recent heavy rains, be sure to dry it out as quickly as possible and dry it thoroughly. Now is a good time to check around your home for any roof leaks or water in crawlspaces too.

For more information about how to prevent and clean mold, visit University of Illinois Extension's free website, "Healthy Indoor Air" at http://web.extension.uiuc.edu/healthyair/mold.cfm.

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