As the grip of winter loosens and the first signs of spring begin to peek through, some homeowners start noticing something unexpected: cracks in their windows. If you’ve spotted a crack and are scratching your head, wondering “how it got there?”, you’re not alone. One of the most common culprits behind these mysterious cracks is something called thermal stress. At Storm Master Exteriors, trusted experts for window installation in Saginaw, MI, we’ve seen our fair share of these issues, and we’re here to help you understand what’s going on, how to spot it and what you can do about it. Let’s break it down.
First things first: what exactly are thermal stress cracks? Simply put, they’re cracks that form in glass when there’s a big difference in temperature between one part of the window and another. Think of it like this: if you’ve ever poured hot water into a cold glass and watched it crack, you’ve seen thermal stress in action. The same principle applies to your windows.
During winter, your windows are exposed to some pretty extreme conditions. The edges of the glass, which are in contact with the cold window frame, stay chilly, while the center of the glass might warm up from sunlight or your home’s heating system. When one part of the glass expands (because it’s warm) and the other part stays contracted (because it’s cold), the glass gets stressed out. If the stress gets too much, the glass cracks.
Now that you know what causes these cracks, how do you recognize them? Thermal stress cracks have a few key characteristics that set them apart from other types of damage.
For starters, they’re usually straight and run parallel to the edge of the window, often starting at the edge and working their way inward. Unlike cracks caused by an impact, which tend to spread out in a spiderweb pattern, thermal stress cracks are more orderly in their appearance.
Another sign is that these cracks often appear suddenly, especially when the weather starts to warm up after a cold spell. One day, your window is fine; the next, there’s a crack. And if you’re looking at a crack and thinking, “But nothing hit this window!” thermal stress could very well be the reason. These cracks happen because of temperature changes, not physical impact.
It’s also worth noting that thermal stress cracks can get worse over time. If you ignore a small crack, it might grow larger as the glass continues to expand and contract with temperature changes. Eventually, it could lead to bigger problems, like a completely broken window.
Winter is tough on windows. The constant back-and-forth between freezing nights and slightly warmer days (or even sunny afternoons) puts a lot of strain on the glass. The edges of the glass stay cold because they’re in contact with the window frame, which is exposed to the outdoor chill. Meanwhile, the center of the glass might warm up from sunlight or your home’s heating system. This uneven heating and cooling create stress points that can lead to cracks.
Large windows are particularly vulnerable because there’s more surface area for temperature differences to occur. Low-emissivity (Low-E) coatings, which are great for energy efficiency, can also play a role by trapping heat in certain parts of the glass. And if part of your window is in the shade (say, from a tree or an awning) while the rest is in direct sunlight, the temperature difference can be even more extreme, increasing the risk of cracks.
While you can’t completely eliminate the risk of thermal stress cracks (glass is glass, after all), there are steps you can take to reduce the chances of them happening.
One option is to choose tempered glass if you’re replacing windows or installing new ones. Tempered glass is stronger than regular glass and better at handling temperature changes.
Another way to protect your windows is by using window films or shades. These can help diffuse sunlight and reduce the temperature difference across the glass.
Proper installation is also key - poorly installed windows are more susceptible to stress cracks because gaps or misalignment can cause uneven temperature distribution. If you’re unsure about your windows, it’s worth having a professional take a look.
So, you’ve spotted a crack. Now what?
The first step is to assess the damage. Is the crack small and stable, or is it large and spreading? Small cracks might not need immediate attention, but they should still be monitored. If the crack is small, you can use clear packing tape to hold the glass together and prevent it from getting worse. This isn’t a permanent fix, but it can buy you some time.
For larger cracks or if you’re unsure about the severity, it’s best to call in the experts. At Storm Master Exteriors, we can assess the damage and recommend the best course of action, whether that’s a repair or a full replacement. If the crack is in an older window, it might be worth replacing the entire window with a more energy-efficient model. Newer windows are designed to handle temperature changes better, so you’ll be less likely to run into the same issue down the road.
You might be tempted to ignore a small crack, especially if it doesn’t seem to be causing any immediate problems. But here’s the thing: even a small crack can lead to bigger issues over time. It can weaken the glass, making it more likely to break completely. It can also reduce your window’s energy efficiency, letting cold air in during the winter and warm air in during the summer. Plus, let’s be honest, cracked windows just don’t look great.
By addressing thermal stress cracks early, you can save yourself money, hassle and headaches in the long run.
Thermal stress cracks are one of those things that can catch you off guard, especially if you’re not familiar with how they happen. But now that you know what to look for and how to handle them, you’re in a much better position to protect your home’s windows. Remember, a little prevention goes a long way, and if you do run into trouble, we’re here to help.
At Storm Master Exteriors, we’re not just about fixing problems - we’re about helping you feel confident and comfortable in your home. Whether you need help with your windows or are looking for a reliable roofing company in Saginaw, MI, we’ve got you covered.
