It may appear as water, frost, or ice on the room surface of windows and doors. The warmer the air, the more water the air can hold, which means that the air in the center of any given room will hold more water than the air adjacent to the window or door walls, since this area is always cooler. When the warm, moisture laden air moves toward the cooler window or door wall it becomes cooler and cannot hold the moisture it held when it was warmer. Therefore, the moisture is dropped and appears as water on the glass and frames of windows and doors. This occurs more frequently during the winter months because of the extreme difference during the winter months, when the average outdoor temperature drops to 35 degrees or less. It would be wise to maintain a 25 to 30 degree relative indoor humidity.

Ventilation is a very effective way to remove excessive moisture from the air, which is why old, poorly insulated houses with single glazed windows, often times do not have condensation problems. This is because the air is changed by infiltration around the windows, doors, vents and other openings. Newer homes, which are constructed to meet current insulation standards and energy conservation requirements, or older homes, which have been newly insulated through the addition of attic and basement insulation, and installation of primed windows with dual or triple glazed glass, are now so air-tight that they present a new problem.

If you have an existing moisture or condensation problem, do not count on correcting it merely by installing new windows. An insulated window should help relieve the situation. You must remember windows do not cause condensation. Therefore, windows cannot cure condensation.