Window Seal Failure: Causes, Signs and Prevention

Seal failure is a common problem homeowners face with their windows, and it’s unfortunately an indication that the window is failing. Broken window seals allow outside elements to enter your home, compromising your comfort and causing your energy bills to spike.

Today, we discuss common causes of seal failure, how to identify this problem and what you can do about it.

Thermal Windows

A thermal window, also called an insulated glass unit (IGU) has two or three panes of glass with open space between the panes. Manufacturers vacuum the space between the glass panes of these replacement windows to remove air and then fill insert a special gas fill, which is usually composed of argon or krypton. This gas fill slows down the rate of heat transfer within the window, boosting its energy efficiency.

However, once the seal on the edges of an IGU breaks, the gas fill can escape and get replaced by regular air and moisture, compromising the insulation of the IGU. While window seals are designed to last for decades, they can fail sooner than that in some circumstances. 

Causes of Window Seal Failure

1. Age – Outdated windows are more likely to experience seal failure. Update the weatherstripping on your windows as recommended by your manufacturer to help maximize its lifespan.
2. Natural Elements – While window seals are made to resist harsh elements, they have limits. For instance, when your sliding windows experience constant rain exposure, water can seep behind the seals and cause them to lift. Since the seal isn’t flush with the window frame, it can allow water and cold air to enter. Water exposure can also cause certain types of weatherstripping to rust, which over time will cause corrosion.  
3. Improper Installation – An incorrectly fitted window seal will move over time and will not be as energy-efficient. The weatherstripping must be installed in a precise location, which depends on the window type and size of the unit. The installer must also use the right tools and fasteners to fit the weatherstripping. 
4. Mold – Condensation can cause mold to grow, which can damage the window seal. It can make the seal ineffective, especially if it’s made of a rubber material. Make sure mold or any discoloration is immediately removed with an alcohol-based cleaner or vinegar to kill the spores. 
5. Extreme Temperatures – Extended exposure to extremely hot or cold conditions or sudden temperature changes can cause certain types of window seals to shirk, sag or crack. 
6. Poor Maintenance – Your window company should provide maintenance instructions for each of your windows. Failing to stay on top of this maintenance can cause the seals of your windows to fail prematurely.

How to Tell If a Seal Is Broken

Clean the interior and exterior of your window to determine if the condensation or grime is inside the glass panes. In some cases, when the gas fills begin to leak from the IGU, the panes can bend and collapse a little in the middle, causing the glass to look distorted or even break. Stand at a distance outside and look at the reflection from the window. If the window’s glass appears more distorted than your other windows, the seal has likely failed.  

Fogging, hazing or the presence of moisture between the two panes are common signs of window seal failure. The fogginess may come and go with the weather conditions. However, it typically occurs when the indoor and outdoor temperatures are very different and may go away as temperatures change. 

How to Deal With Window Seal Failure

You can file a warranty claim with your window contractor or manufacturer. A window that experiences seal failure soon after installation will likely be covered by your contractor. Always read the terms of your warranty when purchasing replacement windows and keep all warranty documents. 

You can have the failed IGU unit replaced. This is probably your best option, especially if the damaged unit is old. Modern windows are more energy-efficient, durable and stronger.  

A window replacement is more complicated than it looks and is best handled by professionals. This work requires skills and experience. Installers go through training from manufacturers to learn how to identify possible problems and provide the best solution. They can work faster and more efficiently so you won’t have to worry about your home being exposed to elements for very long while the work is underway. Also, you need to have the right tools for window replacement. Buying these tools can be very expensive.

Ways to Prevent Window Seal Failure

Choose windows that come with comprehensive warranties. Having the windows installed by the manufacturer will give you access to stronger warranties.

Check your windows from time to time for signs of seal failure. If you detect any gaps, have them sealed at once. Maintaining the cleanliness of your windows can also help. Never use pressure washers to clean windows because the high-velocity water stream can damage the unit.

Do not use a heat gun to remove paint from window frames. Instead, carefully scrape and sand the surface when repainting windows with insulated glass panels. 

For long-lasting and energy-efficient replacement windows, choose Renewal by Andersen® of Eastern NY. Our experienced team installs sliding, bay, casement and double-hung windows. We also offer a wide selection of patio and entry doors. Call us at (866) 479-1700 or fill out our online form to request a free in-home consultation.