Can Windows Crack from Winter Weather?

The short answer is yes, windows can crack from cold weather, and the phenomenon is called a thermal stress crack. Are you wondering, “Why is my window cracked?” Keep reading to learn more!

What Is a Thermal Stress Crack in Windows?

Thermal stress cracks occur where there is a significant temperature change in the glass. The particles of the glass will expand when heated and contract when cooled, and sometimes the degree and stress of this expansion and contraction is too much for the glass to handle. Much the same way if you poured cold water into a glass fresh out of the dishwasher, the rapid change in temperature will make the window crack on its own.

Can Glass Windows Break from Cold?

In most windows, the edge of the glass is covered by a frame. The frame shields those last inches of glass from sunlight and other heating sources, leaving them significantly cooler (or warmer, depending on the weather) than the rest of the pane. When the center of the window pane expands and contracts in response to temperature changes, it pushes and pulls against these last few inches of glass. This pushing and pulling causes tension towards the edges. If this tension is too much, a thermal stress crack will form perpendicular to the edge of the glass.

Factors that Contribute to Thermal Stress Cracks

The type of frame you’re using matters. Frames made out of an insulating material like timber or vinyl will keep the edges cooler, while aluminum or other metals will conduct heat. A dark color frame will also absorb more heat than a light color.

Where your window is in relation to your heating vents can make a big difference in the winter, and in cold weather in general. If your glass has cooled significantly and is suddenly exposed to lots of heat coming up from the vents, it has a higher chance of cracking.

Along the same lines, where your window is on your home also makes a difference. Is it under an overhang that is likely to see a big shift in sunlight as the seasons change? Is there a shadow falling over it that will create consistently uneven temperature distribution? Keep these factors in mind when you’re planning for window installation.

The temperature of the glass depends on how much heat the glass has absorbed. If glass is heated by the sun during the day and there is a significant, quick drop in temperature after the sun sets, this drastic change in temperature may cause a stress crack. Thermal stress cracks form most often in large, newer windows. The larger pane a window has, the harder it is to keep all the glass the same temperature.

The edge strength and type of glass are also factors. Clean cut glass is the strongest edge to have, and after that, a polished edge is the strongest. There are tons of different types of glass to use in your windows, so consult with your window professionals to determine which one is right for you.

Can You Prevent Thermal Stress Cracks?

Since thermal stress cracks are a naturally occurring phenomenon, there isn’t a lot you can do to prevent them other than making sure you use the right glass, edges, frame, and placement of your windows.

If you have any questions about preventing thermal stress cracks or have a window that needs replacingcontact the professionals at Shanco for all your window needs in the Washington, DC metropolitan area.



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