water condensation problems on windows

New windows can now be rated with a condensation resistance coefficient, using a scale of 1 to 100 (the higher the better).

The use of fiberglass or vinyl frames (instead of aluminum) and, most of all, details involving the glass panes and the warm hedge spacers at the edge of the glass can raise the thermal resistance of the interior of the windows, making them less prone to water condensation.

Windows with a high U-factor (insulation resistance) have also a good Condensation Resistance Coefficient.

In humid climates, choose a window with a high U-factor or a high Condensation Resistance Coefficient (more than 80, 1-100 scale). That's important to avoid foggy windows and fix condensation problems.

Water condensation problems On Windows and around them

Water condensation on windows can leak into the walls and be a cause of mold, rot and other damages that sometimes go unseen. Anyway, to prevent it, you need more than just windows with a high Condensation Resistance Coefficient.

In cold-humid climates (especially in wood-frame homes) the rough opening should be carefully sealed; possible gaps and openings should be thoroughly caulked and foamed.

Installation is very important, and should be done by knowledgeable contractors.

The causes of Condensation on Windows may not be in the Windows

Typically, excess moisture appears on windows because windows are the coldest surfaces in the house; but that doesn't mean that the the problem is in the windows, and chances are that the moist air is also accumulating on other surfaces, such as wall and roof cavities – with even more serious consequences…

The problem of condensation and fog on windows may have deeper causes: internal sources of moisture (baths, laundry, cooking... and defective exhausting systems), attic and basement leaks, bringing outside moist air into the house...

See: Moisture Guide




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