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How to Tell If Double-Pane Window Seals Have Failed

Most replacement windows today are equipped with double-pane glass, which utilizes a sealed airspace as a form of insulation. Sometimes the seals on these windows fail, which may compromise the unit’s long-term performance and energy efficiency. In today’s post, custom windows company Renewal by Andersen® of Austin explains how to tell if your window seals have failed.

How Double-Pane Glass Works

A standard double-pane glass assembly consists of two glass panes separated by insulated spacers. The gap between these panels serves as the insulating layer and is vacuum-sealed at the factory. With no air molecules to conduct heat, thermal transfer is dramatically decreased on an otherwise naturally conductive material. Renewal by Andersen offer an optional insulating gas fill for these windows, which further enhances insulation levels.

How Seals Fail

Sometimes the seals on double-pane windows fail, even in the best of circumstances. Similar to caulk, the seals around these glass panels may deteriorate with age. In some cases, seal failure may happen even if the windows are new. The most common cause is when replacement windows are transported by air, as the difference in atmospheric pressure exerts itself on the vacuum-sealed components. With Renewal by Andersen, this is not a problem. All our replacement windows are crafted in Minnesota, just down the road from where our parent company, Andersen® Corporation, is headquartered.

Signs of Window Seal Failure

The following are clear signs your window seals have failed:

Glass Distortion — Double-pane windows with leaking insulating gas fills will appear distorted. As the airspace shrinks, the panes will appear as if they’re drawn to each other, which is more pronounced at the center.

Condensation Between Panes — Condensation between glass panes is impossible to wipe off and may indicate a larger problem: window seal failure.

Discoloration — Soot and other particles may infiltrate the airspace in the glass, resulting in noticeable discoloration that can’t be removed by just wiping off.

What Should You Do?

Window seals are applied during manufacture; therefore, early failure can be considered a factory defect. Most replacement window warranties cover window seal failure. In our case, premature seal failure is part of our 20-year transferable limited warranty on glass. Lacking warranty coverage, window seals may be repaired. If your windows at the end of their projected lifespan, having them replaced would be a more practical option.

Renewal by Andersen of Austin is your leading provider of energy-efficient replacement windows, including popular styles like casement windows. Give us a call at (512) 298-2270. You can also fill out our contact form to schedule an appointment. We serve customers in Austin, TX, and surrounding communities.


"Renewal by Andersen delivered a superior product with superior customer service, the best construction, experience and all promises completed professionally and in a timely manner. All my windows were replaced in one day"

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