Double pane windows seem like the best choice because they provide better insulation and increased noise reduction. They do usually perform better than single pane windows, that is unless the seal fails. A failed seal allows moisture between the panes, which results in condensation and impossible to clean water spots. Knowing the causes can help you repair the window before condensation becomes a problem.
The Cause of the Problem
The windows consist of two panes of glass sealed together with trapped air or gas trapped in between. If the seals or frame that bonds the two panes together fails, moisture can make its way between the glass. This shows up as condensation, or as water spots after the condensation dries.
Common causes of seal failure include:
Water collecting on the window seal or sash.
Slamming or banging a window shut, which can weaken or break the seal.
Damage to the seal from ultraviolet rays.
Excess heat, which causes the windows to expand and retract. This eventually weakens the seal.
Improperly installed double pane windows.
Older windows that are due for replacement.
Repair or Replace
Once the seal breaks, there is little you can do other than replace the window. Fortunately, it's rare for multiple windows to lose their seal at the same time. Use the replacement of one window as an opportunity to repair your remaining windows before they meet the same fate.
The first place to check is the sill. If water is collecting on the sill, it can damage the frame that holds the panes together. Repairing the sill so it slants away from the window can prevent water from pooling. Proper eaves and gutters on the roof above the window is another fix.
This is also a good time to inspect the frames for any stress damage. In some cases, a repair person can fix issues with the frames or the seal – as long as condensation hasn't already occurred. They will also perform a full inspection to make sure the remaining windows were installed properly, and to fix any installation issues before you're stuck with full replacement.
Keep in mind, not all condensation means a failed window. If the moisture is on the exterior of the panes and not trapped between them, it's likely caused by high humidity in the house or from a major difference in outdoor and indoor air temperature. This type of condensation will clear up once the temperatures and humidity levels balance, so it's only a short-term issue. (For more information, contact Gary D Torgerson Co about window repair)