What Causes Double-Pane Windows to Fail?

What Causes Double-Pane Windows to Fail?

October 21, 2020

Most residential properties have double-pane windows to provide extra insulation and prevent heat transfer from inside to outside (or vice versa). Over time, though, the seal in double-pane windows can lose its effectiveness, resulting in air loss. This problem is most noticeable when you start to see cloudiness or condensation showing up on your windows.

Here’s an overview of what you should know about double-pane window failure in Alaska and what you can do about it.

Added insulation

Glass on its own does not make for a particularly effective insulator. This is why single-pane windows have been out of style for a long time in residential properties. The use of double-pane windows with a sealed air space between them provides for much greater insulating effectiveness.

The process of creating this type of window involves taking two panes of glass and bonding them together with a bead of sealant around the perimeter of the glass. The result is anywhere from ½” to ¾” of space in between them. Most dual-pane windows have two seals on the perimeter, an exterior and an interior, providing some backup in case the exterior seal fails.

Aside from the sealant, there is also a tube or spacer made out of aluminum designed to keep the glass panes consistently spaced. These tubes might have moisture-absorbing beads to prevent windows from fogging up if the outer seals are compromised.

Causes of failure

Windows are one of your home’s front lines of defense against the exterior elements, so they undergo a lot of stress every single day. They deal with significant temperature swings, varying levels of exposure to ultraviolet light and exposure to rain, wind, hail, snow and ice.

Here are some of the most common causes of double-pane window seal failure in Alaska:

  • Old age: All windows will eventually reach the end of their useful life. The seals will not last forever—even high-quality sealant breaks down eventually as it becomes more and more brittle. When this occurs, moisture will get inside the window. The good news is that this will take a while. Only one percent of double-pane windows will experience sealant failure after 10 years, and about 15 percent after 15 years. Once you get past 20 years, it becomes a more common issue, but there are some windows that will last multiple decades without running into this issue.
  • Heat: Windows are constantly exposed to sunlight, and the heat of the sun will cause expansion and contraction in the windows that can damage the seals. Over time, this will cause cracks that allow moisture inside the window seal.
  • Water exposure: Windows that have excessive water exposure are more likely to experience sealant failure. This is because they are not designed with sufficient drainage to prevent puddling around the seals. If water continually builds up at the seals, the moisture will get sucked into the window unit.

For more information about window seal failure and how to address or prevent double-pane window failure, contact the window contractors in Alaska at Replacement Glass. We’d be glad to answer your questions and address your concerns.

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