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Home Improvement

Thermal Stress Cracks & Common Reasons Windows Crack

2 min read

It’s a homeowner’s worst nightmare. You wake up, grab a cup of coffee and look out the window — and then you see the crack in your window’s glass. Instead of the plans you’d had for the day, now you’re looking for a quick, temporary fix for the window before calling around to get it fixed or replaced entirely. Curious what led to this unfortunate turn of events? Let’s discuss the most common reasons windows can crack, and how you can fix them. 

Common Reasons Windows Crack

Stress Cracks from Weather Patterns

If the weather has been fluctuating between warm and cold, thermal stress cracks can form in your windows from the expanding and contracting of glass with the weather changes. Stress cracks start small, usually on or near the edge of the window, and grow larger with prolonged exposure. It’s worth taking care of these when they appear for that reason. Over time, they can spread across the entire glass pane. We’d recommend a replacement window pane as soon as possible for this reason. 

Thermal stress cracks can also come about if it’s very warm or very cold outside and you turn your heater or air conditioning in the extreme opposite direction to counter it. Pay attention to your windows in these conditions! 


Whether it’s a misplaced golf ball, a rock or a child’s baseball game gone wrong, projectiles can lead to cracks and fractures in your windows. These cracks are tricky, since there’s usually some cleanup involved. Unlike stress cracks, windows can break under the impact of whatever hit them. With this comes broken glass. 

It’s likely best to leave cleanup for this to the professionals if there’s a significant amount of broken glass, though you can sweep up the larger shards while carefully covered up with proper footwear to ensure you won’t be harmed. Close the area off until professionals arrive if you have pets or children, though, to ensure they stay safe. Additionally, you can cover the affected window area with a trash bag to keep the outdoors at bay until your window repair specialist arrives. 

Pressure Changes

Pressure can cause cracks, too. This type of crack is most often found in insulated or double-paned windows and doesn’t have as easily identifiable a reason for causing window breakage as the other types. These cracks can occur when the windows are installed at a high or very low elevation or during dramatic pressure changes due to weather conditions. If the window’s insulation does not match up to the elevation levels outside, a crack will quickly form. 

In addition to having a less obvious visible source as compared to an impact-related crack, these cracks often require a total window replacement. You’ll want to go ahead and get in touch for a replacement as soon as possible to minimize potential damage. 

Windows You Can Depend On

If your windows are suffering from stress cracks or more acute damages, it’s time to consider upgrading to high-quality replacement windows from Window World of Muscle Shoals. Made with durable double-paned glass and custom-built to fit your home’s specifications, your windows also come with quality service. This extends not only to the installation process but long after as well — Window World’s lifetime warranty ensures you’ll have help in the unlikely event your windows become damaged and need to be replaced. Contact us today for a free estimate on windows built to last!