Failed Window seals

​Many homes today have more energy efficient windows than the old single pane window. Most are vinyl or wood with either double or triple pane glass, with double pane being the most common. Double-pane windows contain two panes of glass separated by a space of air or gas that helps to slow the transfer of heat and cold. A desiccant is also added between the panes to absorb any moisture that may have entered the space during manufacturing. Gases like Argon are used because it is denser than air making it more energy efficient than just air. Double pane windows offer many advantages compared to single pane windows, but one issue that is common in many homes with double pane windows is broken window seals.

Double Pane Window

So, How Can I Tell If My Window Seal Has Failed?

• Windows appear dirty even though they have been freshly cleaned. A broken window seal is no longer able to keep out dust and dirt.
• Condensation occurs between the panes of glass.
• The windowpanes appear distorted in the center.

Condensation Between the Glass

Window Staining Between the Panes

When a window seal fails, moist air seeps in between the glass panes and condenses on your windows, causing window fog. And while the fog may eventually go away with weather changes, now that the seal has failed, the problem will likely continue. Fortunately, a broken window seal is not a serious issue in most cases. While window seal failure removes much of the energy saving features found with double or triple pane windows, it does not negatively impact the function or look of the window aside from the occasional presence of window condensation.

Foggy windows can be repaired using a defogging procedure. While still a newer repair option, window defogging can produce cosmetic results that help improve visibility in your windows. On the downside, defogging does nothing to restore the window's insulating ability (R-value) to its original level.

However inconvenient fogging is, it isn’t the only issue commonly seen in double pane windows. There are times that a window may appear stained or glossy from the exterior of the home. This condition happens whenever the seal of a Low-E window fails. Low-E, or low-emissivity, glass was created to minimize the amount of infrared and ultraviolet light that comes through your glass, without minimizing the amount of light that enters your home. Low-E glass windows have a microscopically thin coating that is transparent and reflects heat. While it might be possible to replace the glass with a low-E/argon-filled glass, you should consider if the repair is worth the investment. The better option might be replacing the entire window with a newer window because it is labor intensive, which adds up to more cost.

If you have concerns about about the condition of your windows, contact a licensed Home Inspector to learn more about your window condition and possible repair or replacement options.