Over the years we’ve received a few calls each winter from customers who’ve built a new modular home with us. One reason for their calls was the “ice dams” that had formed on the eave edge of their roofs. I’ll discuss this condition in a later post. The other reason they called was concern about the moisture condensation on the inside of some of their windows.
Moisture Condensation: The First Heating Season
Moisture condensation happens quite frequently at the beginning of a new home’s first heating season. This is true regardless of the type of wood frame construction. As much as a ton of moisture (yes, 2,000 pounds!!!) can be released by the lumber, concrete foundation, and drywall as they dry out. The condensation can appear as fog on the windows and can even freeze on the glass. Moisture condensation is most likely to appear on windows, rather than walls, because glass surfaces have the lowest temperature of any interior surface in a home. When the warm, moist air comes in contact with the cooler glass, the moisture condenses. The same action occurs on the outside of a glass of iced tea in the summer and on the bathroom mirrors and walls after you take a hot shower. If condensation occurs in your new home, you will need to provide ventilation to dissipate the moisture. Turning on the kitchen and bathroom ventilation fans each day or briefly opening a few windows, especially during the first heating season, should take care of the problem.
Moisture Condensation: Daily Living
Moisture condensation can also build up in a home after the first year because of normal living. If the problem continues, you should remind everyone in the family to use the bathroom ventilation fan when they are bathing and the range hood fan when they are cooking. Today’s tight homes are more prone to retain moisture from cooking, bathing, drying clothes, operating humidifiers, heating with fossil fuels, and breathing. Proper ventilation, however, will maintain the right amount of moisture in your home to balance comfort and safety. If an abnormally wet situation exists, use a dehumidifier. Otherwise, problems may result, such as peeling paint, rotting wood, buckling floors, insulation deterioration, mold and mildew, and even moisture spots on walls and ceilings. Remember, you are responsible for any problems caused by improper ventilation.
Moisture Condensation: Exterior Causes
Excessive moisture condensation can also be caused by conditions outside of the home itself, such as high winds during heavy rainfall or a snowstorm. Dampness in the basement, caused by poor exterior grading, a high water table, or other site conditions can also lead to moisture problems in the home. Again, if an abnormally wet situation exists, use a dehumidifier.