Q: I have condensation on the ceilings of my home and have recently discovered mildew at the wall near the floor in a couple of bedrooms. I keep a clean house, but I am concerned I might be doing something wrong. -- Albert
A: We bet that if you did some further investigation you would find that you also have condensation in your attic and that the crawl space under the house is damp. This is a classic case of poor or nonexistent ventilation.
Attic and foundation vents allow air exchange between interior and exterior spaces. Their effectiveness depends on the movement of air, whether from natural breezes, fans or connective currents produced by warm air rising and being replaced by cooler air. The most effective venting utilizes cross-ventilation.
Interior ventilation performs two important functions: comfort control and moisture control. Fresh air cools it in hot weather, and also remove steam, smoke, cooking odors and other indoor pollutants from the house. Windows and natural air infiltration help provide this ventilation, but every home also should contain mechanical ventilators such as bathroom exhaust fans, range hoods, and dryer vents all ducted to the outside.
Proper ventilation will help control heat and moisture build up inside the home, and in the attic, crawl space, and uninsulated wall cavities. Many of the home improvement centers that sell ventilation products have step-by-step instructions available on how to install them.