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If you don’t know much about Can heat cause a window to crack? The answer is yes. Heat can cause a window to break, but do you know why? if not, then keep reading because there are tips included in this article, through which you can avoid window cracks and much more. Moreover, this article covers a complete guide on why and how heat causes a window to crack. It is just because of thermal stress. 

Causes of a Window Thermal Stress Crack

Thermal stress is caused by the glass’s exposure to different temperatures. The causes of thermal stress cracks could be other, but some are discussed here. Temperature variation is the leading cause. 

When the window is directly exposed to the sun, the temperature on the central parts of the window will be maximum while the temperature on the outer edges of the window will be low. 

High temperature at the main part of the window will cause the window to expand at different rates. That will also put pressure on the outer regions, which will lead the window to crack. 

One of the most common examples is from our kitchen. When we rinse a hot cup under cold water or a cold dish under boiling water, suddenly, you see the cup cracks from the center while other parts keep expanding. This is actually a thermal shock effect. The same is the case with windows. 

Windows are fitted in an open environment, meaning that windows go through the day’s heating and cooling cycle. This heating and cooling cycle’s effect becomes the leading cause of window cracking.

Why Do Large Windows Seem to Crack More Often?

Usually, more oversized windows tend to crack more than small ones because more oversized windows are mostly placed outside where there is direct sun exposure. 

The part of the window under direct sunlight starts expanding and puts pressure on the window’s more excellent edges. This mechanism makes oversized windows crack more than smaller ones. 

Quality Glass, Quality Strength

Heat causes a window to crack, but what about the quality? Quality matters a lot. Better quality glass has better strength. Some types of glass, such as tempered glass, can bear heat at maximum. The heat from the sunlight is bearable for this glass type; it only suffers breakage from fire. 

Tempered glass can withstand temperatures up to 470ᵒF. So, it is clear that tempered glass is heat resistant. It is mostly used in home appliances such as kitchen cabinets, stoves, windows, etc. Moreover, this type of glass can be used for places in direct contact with heat because it is heat-resistant, versatile, starch-resistant, safe, and robust.

Glass Bearing Capacity

There are some glass types along with temperature bearing capacity:

Additional Tips To Avoid Cracks

It would help if you remember the following things about the stress cracks:


As already discussed, stress cracking is a natural process, so we can’t prevent this, but we can do some best practices to save our windows from cracking, such as proper shading. You can also plant a tree from the shading of windows. 

Consider upgrading to energy-efficient windows to ensure your home’s comfort and safety. Contact BLVD Windows and Doors for expert advice for high-quality replacements. Let’s make your home safe from temperature extremes – get in touch today for a consultation.

author avatar
Sanita Gavrilova