The moisture that suddenly appears in cold weather on the interior or exterior of window and patio door glass can block the view, drip on the floor, or freeze on the glass. It can be an annoying problem.
While it may seem natural to blame the windows or doors, interior condensation is really an indication of excess humidity in the home. Exterior condensation, on the other hand, is a form of dew – the glass simply provides a surface on which the moisture can condense. What are some ways to control window condensation?
Reduce the indoor relative humidity in living areas, attics, and crawl spaces. The following are a few general suggestions:
■ Reduce the amount of moisture you put into the air. This can be accomplished by recognizing the many sources of moisture in the air—from cooking to heating to plants and other items.
■ Vent all gas appliances, the clothes dryer, and exhaust fans to the outside. In most climates you should also ventilate your attic and crawl space to the outside. If you have a crawl space it is very important to completely cover the earth with an effective vapor barrier. If you run a humidifier you may need to turn it down or off.
■ Drapes and other window coverings can contribute to a condensation problem by restricting the flow of warm room air over the glass surface. Therefore, indoor condensation is more apt to occur when the drapes are closed or the shades are pulled down.
■ Make sure you run the exhaust fans in the kitchen when cooking and in the bathroom when bathing or showering. Run the exhaust fan until the mirror in the bathroom is clear or the temperature near your stove is back to normal. Be careful not to run the exhaust fan too long and overheat the motor.
■ Avoid storing firewood in your house or basement.
■ For products with the interior insect screen, removing the screen in the winter months when the window is not typically being operated may reduce condensation behind the screen by increasing air flow.
■ If you have a forced air furnace, make sure your home is properly ventilated by installing a fresh air intake. Or if your home is extremely “tight” and you have excessive moisture, it may be helpful to install an air-to-air heat exchanger.
For more information on the causes of and cures for window condensation, call your Renewal by Andersen showroom and ask for our free booklet, “A Guide to Understanding Condensation” or contact the following resources;
National Fenestration Ratings
1300 Spring Street, Suite 500
Silver Spring, MD 20910
Energy and Environmental Building
10740 Lyndale Ave S., Suite 10w
Bloomington, MN 55420-5615