Q Mildew occurs on the inside wall of a bedroom in our 15-year-old frame-and-stucco house, especially behind the furniture. There is dampness in the cavity between the studs. What should we do to solve this annoying problem? The crawl space under the house is well ventilated but constantly wet during the rainy months. We have installed exhaust fans in both bathrooms and maintain the indoor temperature at 65 degrees instead of 70 as before. R. E. Chadwick Los Gatos, Calif.
A The culprit triggering the mildew, as you suspect, is dampness which is probably rising from the wet crawl space under the house. If you control the dampness or remove it, the mildew should go.
First, take all practical steps to prevent the rain or ground water from standing near the foundation, either inside or out. Make sure the rainwater from the gutters and downspouts runs away from, not toward, the building. Minimize or eliminate any watering from a hose near the foundation. Don't allow any lawn sprinklers to spray water toward the house.
Now, spread a layer of 6-mil polyethylene sheet over the entire ground in the crawl space. Tape the overlapping joints. Run the sheets up the foundation wall and fasten them to the interior. This will stop any moisture from rising up into the floor and stud-wall system, thereafter discouraging mildew by preventing its feeding on humidity.
Ventilation of the bedroom itself will also help to reduce the humidity and dry out the area.
Control mildew before repainting with a mixture of three parts water to one part household bleach. Scrub the affected areas until clear. Then use an interior plant which contains mildewcide.
If you place cups of silicone gel in tight areas it will be helpful in absorbing moisture. You can obtain it at hobby shops, among other outlets.
The commendable reduction of the thermostat setting from 70 degrees to 65 can have an unfortunate kickback sometimes and result in the intrusion of mold.