How to Fix a Broken Window Seal

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If you have windows with double or even triple panes of glass, you have made the right choice for your home. You’re going to cut energy costs, make your home more comfortable for your family, and have a better connection with the outdoors. But this only works if all of the seals are working as they were designed to. Whether it’s the elements or the passage of time, windows are susceptible to failure and that’s when things become problematic. 

When it comes to total window replacement, seal failure is often the main reason why. But at Milano Windows and Doors we want to help you out, so we crafted this guide centered around everything you need to know about broken window seals. After reading this article, you’ll know what causes them, how to spot them, and hopefully how to prevent them.

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What is a Window Seal?

In the old days, windows only had one pane of glass. It was good enough for the times, but modern technology has advanced so much that new windows are very good at cutting down on your heating and cooling costs. They also keep your home quieter as they utilize the power of two or even three panes of glass. 


In some cases, there’s an added layer of gas insulation. The gas called argon is injected between the panes before the window is sealed. These panes of glass are your family’s defence from the elements. They keep you cool in the summer and warm in the winter, unless there’s a window with a broken seal of course!

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6 Causes of Window Seal Failure

So why do window seals fail? Window seal failure is caused by a few main issues: 

  • Age: Older windows are more prone to faulty seals. Our team and many window manufacturers will always recommend homeowners update the weatherstripping to make their windows last longer.
  • Natural Elements: Even the best windows can bend to mother nature’s will. Window seals can take a beating from rain or snow, but if unrelenting moisture is hitting your windows, eventually it will break the seal, causing your seals to no longer be flush with the frame. This will allow cold air in. Some kinds of weatherstripping will also start to fail if it’s prone to rusting under consistently damp conditions. 
  • Improper Installation: If your window’s seals weren’t installed properly, you won’t get the same kind of savings you’d expect on your energy bills. Weatherstripping installation requires the right hardware and tools if you want it done correctly. You also need the knowledge to make adjustments depending on the size and type of window. 
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  • Mould: Continuous damp conditions can be the perfect environment for mould growth and this can eat away at your seal. Rubber seals are especially susceptible to mould. If you ever notice mould growth, use vinegar or a cleaner with alcohol in it to get it all gone. 
  • Extreme Temperatures: Whether it’s really cold or really hot weather conditions, too much of either can cause some window seals to crack, warp and come loose. 
  • Poor Maintenance: Every time you buy a window, it’s going to come with instructions. That manual will contain everything you need to know about preserving and taking care of your windows. Neglecting to read and follow these instructions will only cost you more money in the long run.
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5 Ways to Identify Window Seal Failure

So now that we know the cause of a failed window seal, how do you know if a window seal is broken? It’s quite easy to identify the problem in your own home. The first step is to undertake an intense deep clean of your windows. This will make it easier to spot any potential failures, and because you need to use your eyes for a visual inspection, removing any extra dirt, dust and debris are essential to avoid missing something critical. 

Now that your windows are clean, it’s time to check out your windows to see if you notice any of the following problems: 

  • Cold, Drafty Home: If you stand by a particular window in the winter and it gets really cold or if your home just feels really drafty no matter how much you crank the furnace, it’s probably because there is an issue with your window seals. However, poor insulation in a home could also be causing the cold.
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  • Excess Condensation: You just cleaned your windows but are they still hard to see through? Sometimes if the window seal has broken, there will be moisture between the panes of glass or your windows may seem milky white in appearance. Another sign to look out for is foggy-looking windows. An important note: Don’t be confused by a little bit of condensation on the outside of the window. The only time you need to be concerned is if the water is between the panes of glass. 
  • Glass Distortion: This is a serious one. Sometimes if your seal is broken gas will leak from an insulated window. In this case, the panes may start to bend or even break. Try to compare your window to other windows in the house. If you notice something looking off, get help fixing the seal immediately. 
  • Insects: Just like moisture between your panes of glass, insects and bugs between your panes of glass is also a really bad thing. This can mean that insects can in some cases also make their way inside your home. 
  • Windows that Are Hard to Open and Close: It’s also time to think about calling for repairs when your windows don’t open or close properly. If you’ve been carelessly propping open windows, then you need to get it fixed before anybody gets hurt —especially pets or children.

Window Seal Broken? 


So you’ve figured out that your window seals have failed, so how to fix a broken seal on a window? Fixing your window seals is not really a DIY project and that’s why the window installation and repair professionals at Milano Windows and Doors are standing by to help. We are the GTA’s most trusted broken window seal repair service and we always guarantee your complete satisfaction. Call us today to get your estimate and book an appointment.

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