Keeping Moisture Out Will Help Keep Mold Out

By Amy Winter

January 4, 2008 5 min read


Keeping moisture out will help keep mold out

By Amy Winter

Copley News Service

Everyone knows a piping-hot shower steams up the bathroom mirror. But did you know that condensation is a major culprit in bringing mold into the home?

Mold reproduces by spreading spores, says Rhonda Mowday, a certified industrial hygienist. With millions of spores in the environment all the time, it's easy for mold to multiply when conditions - food, temperature and moisture - are right.

Mowday says molds eat cellulose-based substances such as wood, paper, textiles or decaying organic materials. Most molds thrive in warmer temperatures from about 60 to 80 degrees. And since mold spores and food sources are always present, the key eliminating indoor mold growth is to eliminate moisture.

"Mold is most commonly found where there is water intrusion," says Ralph Szaras, another industrial hygienist. "It can be from a pipe leak or water coming in from a roof leak. But on a typical basis, mold growth is usually found in the bathroom and kitchen."

Szaras recommends using ventilation to avoid adding moisture to the walls and ceilings. Either open a window or turn on the fan to move the air outside the bathroom. When cooking in the kitchen, use the exhaust fan.

"Fans move air and blow it against walls, evaporating the liquid water," says Tim Carter, a custom home builder who runs the Web site "Get it out of the house through ventilation."

Jason Kintner, project manager at Telum Inc., a contracting company and member of the National Kitchen and Bath Association, advises homeowners to have a comprehensive water intrusion plan. It should begin with the design and continue into the construction. Talk with your contractor to make certain that he or she has a plan to deal with water leaks and ventilation. Kintner says our more energy-efficient homes cause the structures to become more airtight, meaning any water present in the walls or under the house can't leave; it sits and becomes a breeding ground for mold.


Chemicals that act as mold inhibitors are spreading to other building materials. Carter says there is a drywall that uses layers of fiberglass instead of paper, which can be eaten by mold. In the last three to four years, the U.S. Steel Corp. has been marketing an anti-mold stainless steel for surfaces in kitchens or bathrooms. Copper is the best-kept secret as an antimicrobial, according to Carter. Copper is put in certain roof shingles to prevent roof algae.

"Incorporate small pieces of copper where water is present," says Carter. "A bathroom would probably be mold-free with strips of copper in the shower area."

Add antimicrobial agents to paint to stop mold growth on walls. Szaras stresses that a homeowner must keep the walls clean, since the layer of dirt hinders the paint from working.

Mold problems can be a seasonal issue. Tom Kenney, vice president of research and engineering at the NAHB Research Center, says moisture condenses on cold walls when outdoor humid air enters the house during the summer. He recommends buying a dehumidifier to reduce indoor humidity. During the winter, try not to use an indoor humidifier.

To control mold, Mowday suggests fixing any leaks on faucets, water lines or toilets. Keep up with cleaning your home. Dry wet materials within 48 hours of a flood. Keep the intersection between the tub and tiles sealed with caulking.

Mold will die once the water source is removed. Regular soap and water can kill mold; you don't need a special chemical. Szaras says bleach and water will destroy mold, but it is adding more chemicals to your surroundings. Oxygen bleach is another option that is less toxic to humans.

If cleaning mold in a small area, use a damp cloth and a high-efficiency particulate vacuum to avoid spreading mold spores, according to Mowday. If you decide to use bleach, wear gloves and protective eyewear.

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