Taking Steps To Control Moisture Will Reduce Possibility Of Mildew

Q. Last fall two new tenants moved into my rental home. Lately I’ve noticed there is mildew on some of the outside walls along the baseboard, in the bedroom closets, and window sills in the kitchen. I know they regularly cook pasta. Mildew has never been a problem in the past.

The house is well-insulated and has double-pane insulated windows. When I was there, the house felt damp, bedroom doors were closed, and they had wet laundry hanging in the basement. Please pass on some pointers I can tell them so we can get rid of the mildew problem.

A. Excessive moisture in the home can be a common problem and nuisance especially in the winter. Moisture can cause mold and mildew growth and stain ceilings and walls.

If not remedied, such conditions can also promote wood decay, the blister paint and reduce the effectiveness of insulation and cause health problems.

Moisture problems that are site-specific can sometimes be complex and persistent. Finding a solution takes a little bit of detective work. Common sources can often be controlled by minor changes in lifestyle.

You mentioned three common sources of indoor moisture: cooking, wet laundry and closed-off rooms. Three options to reduce mildew are warming up the surface, increasing air circulation and reducing moisture generation.

During the winter, external walls are generally cooler than other room surfaces. There is often very little air circulation behind furniture or in closets. These are prime targets for moisture problems. Warming these surfaces and allowing the air to circulate to them will help prevent mildew growth.

Encourage your tenants to leave their bedroom doors and closets ajar whenever possible. Check with your tenants on how often they are using the electric baseboards. To prevent condensation, a minimum heat level of 65 degrees may be necessary.

Mold in the window sills is often the first indicator that high humidity exists in the home. Continual window condensation forms puddles on the frames and sills; a nice environment for mold and mildew. Condensation occurs when warm moist air inside the house comes into contact with the cold window surface. Window condensation often becomes worse in the winter because of colder outside temperatures, and there’s more moisture in the house because the windows and doors are shut.

You mentioned this is only a problem in the kitchen and not in the bathroom. If the kitchen doesn’t have an exhaust fan, then any moisture from their cooking is evaporating, adding moisture to the air. The simplest remedy is to cover pots and pans when cooking. Since pasta is cooked uncovered, encourage your tenants to open the kitchen window while cooking the pasta. This should be done even when it’s raining outside.

Exhausting warm air to the outside during the heating season to provide proper ventilation adds a small amount to the heating bill but is less costly than the expensive repairs that may be necessary if the excess moisture is not removed.

To protect your property values as a landlord, you should consider installing a range hood ducted to the exterior and a bathroom exhaust fan as well. Adequate mechanical ventilation will help adjust to varying occupancy habits of different tenants.

Hanging laundry to dry in the basement adds large amounts of water to the indoor environment and should be discontinued in any house that has had moisture problems.

If they follow the above tips, the excessive moisture levels in the house should be reduced considerably, enough, it is hoped, to prevent the mildew from reoccurring.

For more information, contact the Energy Hotline at (800) 962-9731 or 324-7980. Ask for a free information guide, “Reducing Moisture Problems.”

xxxx