Windows help protect a home from the weather while letting in natural light and, when open, fresh air. In an insulated double-pane glass unit, a seal between the panes keeps moisture out of the enclosed space. When that seal fails, moisture can enter and leave the glass cloudy.
Here are the signs we look for when assessing a failed glass seal.
Three clues to look for
- Condensation trapped between the panes. Moisture inside the insulated glass unit cannot be wiped away from either accessible surface. It is a sign that the seal between the panes has failed.
- Fogging that remains after cleaning. Cloudiness between the panes is different from ordinary dirt or temporary condensation on the room-facing or outdoor surface.
- Black seal material is bulging into the visible glass area. Have the perimeter of the unit inspected.
Moisture on an accessible surface does not by itself prove that the seal between the panes has failed. Locating the condensation is an important first step.
Does a broken seal mean you need a new window?
Often, only the insulated glass unit needs replacing. The unit consists of panes of glass sealed together during manufacture. A failed unit is replaced as a sealed assembly; repairing the existing frame's exterior caulk does not restore the seal between the panes.
When the frame is sound and the window is designed to accept replacement glass, it remains in place. The new unit is measured and specified for that opening. Glass appearance, thickness, and grids are specified for the opening, with Low-E matched to your other windows.
Our fogged window glass replacement service explains the assessment and replacement process. If the frame or hardware also has problems, the repair vs. replacement guide can help you understand the broader decision.
Examples of fogged insulated glass
Cloudiness and moisture can look different from one glass unit to another. These examples show why it helps to inspect the glass from both sides and check whether the affected surface can be reached for cleaning.
We serve all of Northern Virginia, including Fairfax County, Loudoun County, Arlington County, Alexandria and parts of Prince William County. Call 703-471-4500 for a free estimate with a written quote. A photograph and the number of affected windows are useful starting details.
