windshield crack

There are a lot of ways a windshield can crack, though some may come as a surprise. Today we’ll look at some of the most common culprits (which can hopefully help to prevent some of said cracks), but before we do, let’s take a look at why it’s so easy for a crack to form.

Glass is made of sand, amongst a few other minerals. Sand is heated to incredible temperatures (3,090° F) that cause it to melt before it’s then cooled into solid sheets used for a variety of purposes.

Now, we’re somewhat oversimplifying this process, but it’s important to understand that when the glass is cooled it appears solid, which to your touch it is. But its molecular structure is more like ice than it is a sheet of steel. At the risk of sounding too ‘sciency’, there are random gaps between the molecules and everything isn’t as closely fitted as it may seem to the naked eye.

Let’s tie what we just learned to the original question – What are the most common causes of a windshield crack?

windshield crack

Temperature Change

One of the most common causes is simply the changing of the seasons.

During the fall your car is slowly engulfed in a layer of frost as the night rolls on. In the morning the sun comes up and melts the frost, heating the glass. So far so good.

Fast forward to winter and enter even colder temperatures and drastic shifts as you run your heater. Again, your windshield is designed to handle this, but over a long period of time the constant temperature changes will put a strain on your glass and cause cracks, but more often will expand a small, unsuspecting crack.

It’s important to note that even sunlight can impact your windshield over time as overheating the glass can be as detrimental as freezing it.

windshield crack


Garbage trucks, cement trucks, lawnmowers, and weed eaters. What do all these objects have in common? They are the bane of glass world ‘round as they either release debris, particularly in the form of stone and gravel, or straight up turn it into a projectile. A bit of dried gravel on a cement truck coming loose on the highway can sound like a gunshot striking your windshield – while only leaving a small, barely visible chip.

Unfortunately, the structure of the glass is now compromised and the results can vary from the chip never growing to spanning your entire windshield.

When on the highway, try and steer clear of driving close behind large trucks carrying a load of any sort. You never know what may come loose.

windshield crack

Pressure Change

You’ve seen the movies, we know you have. A hand grenade goes off in a small room or on a street corner and all the glass in a wide radius is shattered. This is an example of extreme pressure change and it often disagrees strongly with the nature of glass.

Obviously, we don’t live in a Call of Duty game or Arnold Schwarzenegger movie, but pressure change does affect everyone. Think of the last time you drove up into the mountains. The higher you went the more it felt like your ears might pop. This is your body adjusting to the change in pressure. Your windshield reacts to this change as well, and frequent, sudden changes in pressure can cause cracks over time.

windshield crack


There are times when your windshield just isn’t made that well. There might have been a mistake made anywhere from the cooling of the glass to the installation. A poorly installed windshield can crack as it shifts during use. That’s why it’s best to leave windshield replacement and repair to the professionals who know auto glass as well as we do here at Taylor Auto Glass. We inspect all auto glass before installing it to ensure it’s in excellent condition to keep you and your family safe on the road.


For a great explanation of the molecular structure of your windshield glass, head over to Explain That Stuff and check out the diagram toward the end of their post.

Also, for a little bit of fun, watch this video by the Slow Mo Guys to see how extreme temperature change affects glass

Cracks may be scary, but they don’t have to be. The moment you notice a crack, give us a call and let us take a look. Cracks can be contained and repaired if they are small and caught early enough.

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