Window Seal Failure

Window Seal Failure

Window Seal Failure RepairMost buildings nowadays have double or triple pane windows as opposed to single pane windows that you see in older homes. Each pane is an extra layer of insulation between you and the outside environment. Between the layers is a clear, odorless gas such as argon. These windows seal in the warmth during summer and keep the home cool during summer.

However perfect the windows are, the seals protecting the gases can get broken. In this case, the gases can escape the seal. But can you fix the seal? Or do you have to change the entire window?

Our article brings you everything you need to know about window seal failure, remedies, causes, and much more.

What Is a Window Seal?

Window seals are the seals present in the perimeter of the window panes to seal in the gases present. The purpose of window seals is to provide a thermal barrier so that the heat transfer is reduced. They lock in the gas and creates a barrier that blocks the outside temperature from entering your home.

Insulated glass windows (IGU) are two or three panes of glass with inert gas or a partial vacuum between them. The panes are sealed together at the edges to provide an airtight fit and prevent the gas from escaping. And also to prevent the contaminants from entering the space between window panes.

What Causes Fogged Window Glass?

Foggy glass happens when the window seal fails. The sealed environment which holds the gasses is never perfect; Temperature changes, wind, etc., can cause the seal to fail, causing the gasses to escape, and moist air enters the space between the panes, where it condenses. However, you may not notice the condensation until there is a rapid temperature change. If your window’s been foggy enough times, there may even be a mineral deposit.

How to Spot a Window Seal Failure

Nothing much happens when the insulated window first fails. You may not even notice the seal has failed until the weather fluctuates and the temperatures go harsh during summer or winter. During this period, the failures become worse, and you’ll be able to see proof of failure.

Here are some clear signs to help spot window seal failure:

How to Spot a Window Seal Failure - Condensation Forms on WindowCondensation

Window seals help create insulation between the interior and the exterior of your house. Following a failed seal, the window is subjected to climate fluctuations such as temperature and humidity. Unfortunately, it also allows the moist air to seep in, which presents in the form of condensation. But fog appears only when the temperature and humidity fluctuations are prevalent.

Windows Appear Dirty

A broken window seal cannot keep out the dust and the dirt. On windy days, contaminants get blown in along with small bugs and will soon cover your windows. They get trapped between the panes making the window appear dirty.

First, clean the window both inside and outside. If they still appear dirty, it is most likely due to the dirt hidden between the panes of glass.

Window Panes Appear Distorted

When a seal has failed, you can see distortions forming in the center of the glass. This is caused when the gas pocket leaks out of the sealed environment. It is then replaced by air, affecting the structural stability of the window; The changes to the structure of the windows ultimately causing visual changes.

Are Broken Window Seals a Big Deal?

Broken window seals are not as big a deal and not a severe issue. Other than losing the energy-saving features found in double and triple pane windows, you will not lose the use of the window. However, you may also have some amount of condensation along with a blocked view.

Reasons Why Window Seal Failure Occurs

According to the manufacturer, Vitro, Architectural Glass, the gas present in every insulated window escapes at a rate of 1% per year due to pressure differential. This true even for the perfectly constructed window.

Here are some of the other reasons for failed window seals:

  • Installation Issues: Window seals can fail within two years due to mistakes during manufacturing or installation. The reason can be a dirty material, insufficiently dried sealant, or inexperienced sealant.
  • Moisture: The wrong window frame can also cause seals to fail. For example, wooden frames do not work in the Midwest due to their high humid nature. Likewise, aluminum frames do not work well in extreme climates.
  • Sun: The repeated expansion and contraction of gases and the hardening of the materials can cause the seals to fail in west and south-facing windows.
  • Condensation: Condensation on windows is common when there is a considerable difference between the temperatures inside the home and outside. If not wiped regularly, mold can form, causing failure.
  • Damage to the Sealant Material: Using a heat gun to strip paint can cause the sealant material to degrade, and ultimately the seal fails.

Can I Fix a Broken Seal on a Window?

Yes! You can fix broken seals; however, it depends on the quality of the window in question. Also, keep in mind that you cannot replace the gases, just the window seal.

How to Fix a Broken Window SealHow to Fix a Broken Window Seal

The issues behind a window seal failure extend beyond the dirty windows. You lose the insulation it provides and can even affect the structure eventually.

If you are sure that your window seal is broken, here are a few options to fix broken window seals:

Call in the Warranty

Check the warranty for the window. If it is still within the warranty period, you can request a replacement. In the future, ensure that the windows come with a lengthy warranty period.

Replace The Entire Window

Even though expensive, replacing the entire window is by far the best option of all. Your new fully insulated window will save you money in the long term by reducing the power bills. A professional window replacement will cost you approximately $500 with a vinyl frame. However, if it’s a wooden frame, it can be upwards of $1000.

Fix the Broken Seal

If you do not want a replacement, you can fix the broken seal itself. However, this is not a practical option since you cannot do anything about the escaped gases. Also, keep in mind that the reduced insulation will cost over time in energy bills. A professional window seal repair can cost you $100.

Replace the Sash

This option is viable if you have removable window sashes. In this case, it may be easier to keep the existing framework in place. Typically, replacing the sash is an inexpensive option than replacing the window.


Defogging is a relatively new solution where professionals remove the fog trapped with the panes. But it doesn’t do anything for the insulation; it just maintains the appearance of the windows for the time being.

Replace Glass Units

You can also have the glass units replaced. While it is cost-effective, companies may charge higher to install a single window.

Repair vs Window Replacement

When a seal has failed it really needs replaced. While you could repair seals, it is not that easy. Even professionals find it quite challenging to separate the panes, clean and then fasten them again. Moreover, the insides get corroded due to the mineral deposits. And the cost is just not justified when you cannot get a clean job done.


The best solution for a failed window seals is to replace your window as a whole. And to buy yourself a window with a long warranty of 10-20 years.

Additionally, homeowners should perform regular maintenance on the window, frame, and seal. Keep your windows clean and prevent moisture from accumulating on them. Finally, ensure that the windows have good air circulation.

On a final note, inspect your windows periodically to check if your window seal has failed. Monitor the moisture or fog in the perimeter of the window where the seals are present.

Assurance Builders LogoAssurance Builders was founded in 1998 with a commitment to provide our clients a personal and enjoyable home improvement experience. By offering professional workmanship and quality products, Assurance Builders has earned a reputation for excellent work and quality service. If you are in need of a window repair in your home, contact Assurance Builders for your FREE quote today!