3 Common Signs of Window Seal Failure

Window Seal

Learn 3 Ways You Can Tell If Your Window Seal Has Failed

Unless your home still has a single-pane window, your windows have seals, and those seals have the potential to fail. Understanding what window seals are and how to tell if they have failed will help you catch any problems right when they happen.

What is a Window Seal?

The presence of window seals is one of the key differences between single and double or triple-pane windows. Windows with seals are constructed from 2 or 3 glass panes separated by a thermal spacer of inert gas or a partial vacuum. The panes and spacers are sealed together at the edges to prevent the gas/vacuum from escaping and contaminants from infiltrating.

How Can I Tell If My Window Seal Has Failed?

1. Windows appear dirty even though they have been freshly cleaned.

Dirty windows are a clear sign because a broken window seal can no longer keep out dust and dirt. Small particles get blown in between the panes on windy days and become trapped there. Small bugs may also work their way in.

If you have cleaned your windows on both the inside and the outside, but they still look dirty, the dirt is most likely lurking between the panes and is caused by seal failure.


2. Pay Attention to Window Condensation between the panes of glass.

The purpose of window seals is to create a thermal barrier between the inside and outside of the window, so that heat transfer is lessened. When the seal fails, the space between the windows is directly exposed to temperature and humidity fluctuations. Moisture becomes trapped between the panes and is visible in the form of condensation. The condensation is likely to be most prevalent during periods of extreme temperature and humidity fluctuations.

Rather than waiting for the weather to change, you can test for condensation by intentionally creating a temperature differential and observing the results.

If you see water droplets, fog, or frost between your window panes, your window seal has likely failed.


The Best Replacement Windows and Doors at the Best Price

We're the #1 Reviewed Door and Window Installation Service in Chicago for a reason. We know how to help.

Chicago window guys - Logo


3. The window panes appear distorted in the center.

The construction of sealed windows is such that the inert gas or vacuum pocket is designed to exist in a state of equilibrium with the glass panes. If the seal fails, the gas leaks out, or the vacuum is replaced with air. This can alter the structural stability of the window pane itself, causing visual changes.

To check for this, stand outside and observe the window from various angles and distances to look for distortions. The most common area for distortions to initially form is in the center of the glass.

What Causes Window Seals to Fail?

If your window seals have failed, it may be due to defective manufacturing or damage that occurred during shipping or installation.

Extreme weather conditions accompanying temperature and humidity fluctuations are hard on windows and can also lead to seal failure.

Even if you have quality windows installed and have done maintenance perfectly, seals may still fail as the windows age.

Window Seals

What Should I Do If My Window Seals Have Failed?

If you suspect your seals have failed, the first step to take is to pull out your warranty paperwork and confirm whether your windows are still covered. Many windows come with a lifetime warranty that helps protect you from a product failure.

Having broken seals on your windows even if they are energy efficient can have an impact on your energy bills. Whether your windows are under warranty or not, we can inspect the windows and give you a no-obligation quote. Contact us today, and we will be happy to help you get your home’s windows back to looking and functioning their best.

This article was updated on February 22, 2022, to reflect changes in technology and the industry. It was originally published on February 20, 2019.