Condensation on Windows – What does it mean? Good or Bad?

We are often asked by homeowners if they should be concerned about condensation on windows.  The short answer is yes.  If not controlled properly, condensation can lead to mold on the interior of windows and other woodwork in the home.
Condensation is a natural occurrence; you’ll find it in the form of dew on the grass and water droplets on the windshield of your automobile.  It occurs when the air cannot hold any more moisture and is dispersed on the nearest cool or cold surface.  Warmer air will hold more moisture than cooler air as illustrated on hot humid days during our Minnesota summers.
Condensation is not created by windows or doors.  The surface of the windows or doors are an avenue for the dispersal of the excess moisture in the air, based on interior and exterior temperatures and relative humidity factors.

What is Condensation?

Condensation is visible evidence of excessive moisture in the air.  It may appear as water, frost, or ice on the surface of windows and doors.  The warmer the air, the more water the air can hold.  This 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.  The walls next to windows and doors are always cooler.
When the warm, moisture filled air moves toward the cooler window or door, 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.  This occurs more frequently during the winter months because of the extreme temperature difference.
Removing Excess Moisture from the Air
Ventilation is a very effective way to remove excessive moisture from the air.  Older, poorly insulated homes with single glazed windows often 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, older homes that are newly insulated through the addition of attic and basement insulation, or homes with newly installed primed windows with dual or triple glazed glass are now so air-tight that they present a new problem.
Condensation may be the result of one of three occurrences:
With the emphasis on energy efficiency, modern houses today are constructed more air tight than ever before.  While this makes the dwelling much more comfortable and energy efficient, it also causes normal moisture and other air quality problems to accumulate and not escape.

If you have an existing moisture or condensation problem you are concerned about, we’d suggest that you talk to a professional.  They will be able to inspect your home and give you advice on what steps to take to correct the problem.