Energy Adviser: Moisture harmful to home and health



During the winter, moisture clings to the insides of windows in nearly every Pacific Northwest home. Unless your home has a hole in the roof, that moisture isn’t coming from the rain outside. It’s coming from the inside.

Moisture is always in the air around us. Warmer inside air condenses it on colder surfaces. Voila, sweaty windows. Not taking care of moisture problems can lead to structural damage and even health issues. Figuring out the causes of indoor moisture is like fitting together puzzle pieces. Your home, its ventilation and you are among them.

Inside moisture sources include house plants, fish tanks, storing firewood, leaky faucets, mopping floors and hanging wet clothes to dry.

The people living in a home increase its internal moisture two ways–by using water and moisture evaporating from their bodies.

Each day, the average family uses nearly 300 gallons of water for cooking, washing clothes and dishes, washing hands and brushing teeth. Some of this water evaporates and adds to the moisture problem.

Nearly 75 percent water, our bodies lose up to 32 ounces through our breath and sweat each day. In one day, a family of four emits three-quarters of a gallon of water into their indoor atmosphere.

Reducing moisture

Research has identified 100,000 varieties of mold. Like moisture, molds are always in the air. Outside, mold breaks down organic matter and can be beneficial. But inside, moisture attracts mold that can damage your home and health.

Drippy windows can damage window sills, and eventually create dry rot, other structural damage and promote mold growth. Too much moisture in a home can lead to mold and mildew growing on or behind walls and ceilings, or under flooring. This can cause health issues, especially for those with allergies or respiratory problems.

Less serious symptoms of exposure are nasal stuffiness, eye irritation, wheezing or skin irritation. More severe ones include fever and shortness of breath. People with chronic lung illnesses can develop mold infections in their lungs.

How can you prevent home damage and health problems?

When used consistently and correctly, bath and kitchen exhaust fans can help keep your home’s relative humidity levels below 50 percent, according to the U.S. Environmental Agency Energy Star program. An indoor relative humidity of below 50 percent is considered healthy and comfortable. It also makes it harder for mold and mildew to grow.

“Use exhaust fans vented to the outside, especially in the kitchen and bath,” said Bob West, a Clark Public Utilities energy counselor. “Having one in an indoor laundry room vented outside also makes sense.” Make sure your dryer exhaust is vented outside too.

“Run the exhaust fan until the moisture is out of the bathroom completely, which might be up to an hour,” said West. “Fans with automatic timers run long enough to remove moisture and you don’t have to worry about forgetting to turn them off.”

Covering cooking pots with lids reduces the moisture escaping into the air, especially if you run the exhaust fan in the kitchen range hood. Cleaning greasy film, oils and soap scum off kitchen and bathroom surfaces also hampers mold growth.

When cleaning and scrubbing floors or walls or other large surfaces, open windows or use your bath and kitchen fans to vent out moisture.

“By keeping critical areas of your home exposed to dry heat and air movement, it’s harder for mold to take hold,” said West.

Energy adviser is written by Clark Public Utilities. Send questions to or to Energy Adviser, c/o Clark Public Utilities, P.O. Box 8900, Vancouver, WA 98668.