Why Do Windshields Crack?


Ever had your windshield break for no apparent reason?

Well, glass doesn’t really break “for no reason.” There could be several causes for your windshield cracking, breaking or shattering. Let’s take a look at some of the more common ones.

There are, of course, several obvious reasons for a chip or crack in your glass – flying grave or other road debris dropped from the vehicle in front of you on the highway. In those cases, the common sense rule of not following too closely, staying alert and avoiding rides behind open-top trucks can prevent many of these glass mishaps.

But what about the not-so-obvious causes? If you notice your windshield has been chipped, cracked or otherwise broken, consider these possible causes. But more important than the cause is the correction. Take steps to have the glass repaired or replaced as soon as possible.

Possible Causes of Broken Windshields

Poor Installation

Factory-installed windshields usually meet a high standard of safety and construction, but sometimes a windshield isn’t installed as precisely as it should. If the glass is installed improperly, the windshield could be loose – causing vibration – or stressed, which can cause cracks.

Temperature Changes

Severe temperature swings can cause glass to expand and shrink rapidly, especially when you use a defroster or even a car heater. Also, the glass typically heats faster around the edges, so the expansion and contraction is happening at different rates, which can lead to cracks.

Sunlight

Like temperatures, sunlight can cause the same problems. The sun’s heat on metal and other materials around the glass can cause the glass edges to expand faster than the middle of the glass and cause cracks. One way to avoid this is to keep your car in a garage or in the shade, if possible.

Pressure Changes

We’re not talking barometric pressure, but sudden pressure changes from shifting from low to high spends (or vice versa), wind gusts, or even heavy objects resting on the glass, can cause stress cracks.

Hail

We’ve all seen the weather reports of hail storms, with hailstones described as “golf ball-sized” or “baseball-sized.” Hail is nothing more than a ball of ice traveling at high speed when it hits your windshield – and has the same effect striking your glass.

Glass Imperfections

In a few very, very limited cases, the glass installed in your vehicle may have been defective. You may not be able to make this determination, but an auto glass shop may be able to. Quality glass shops are also aware of recall notices for defects involving glass or related items. In fact, Glass.com often notifies its affiliate shops of any such recalls.

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How Serious is a Cracked Windshield?

small-windshield-chip

The Good and the Bad

So the bad news is that you have an unsightly crack in your windshield. The even worse news is that you need to take time out of your day to do something about it. The good news? Having the damage fixed by a trained technician can be a quick and painless process, and for some, it’s already covered by insurance. Plus, Glass.com makes it easy by providing instant price quotes from shops in your area and you can book conveniently online in a matter of minutes.

So how do you know if the damage needs to be fixed?

The short answer is it almost always needs to be fixed.

Assessing the Damage

Damage comes in all shapes and sizes, and every crack should be examined by a trained technician. There are two important factors that will determine if you need a repair or if you need a replacement: the size of the crack and its location. Upon examining these two things, a reputable technician will advise you on the next step to take.

But one thing’s for sure, a damaged windshield is usually more serious than it appears and will more than likely require a repair, if not a replacement.

The Underlying Danger

Your crack may be small now and easy to ignore, but don’t put off having it fixed. One of the most common problems with cracks, if they are put to the side, is that they have the tendency to grow. And temperature is one of the main culprits for this. Fluctuating temperatures can cause the glass to expand and contract which can worsen the problem.

A crack in your windshield already has likely weakened its structural integrity, which can leave you and your passengers vulnerable in the event of an accident, so why wait for the problem to worsen?

Don’t Hesitate

A damaged windshield can be a serious problem and can put you at risk to injury or harm. So don’t wait to have a technician repair or replace your windshield. If you’re not sure where to find a reputable technician, Glass.com offers instant price quotes from shops in your area.

© 2019 Glass.com Inc. All Rights Reserved. No reproduction without expressed written permission. Questions? Contact info@glass.com.

Glass.com attempts to provide accurate information but cannot be held liable for any information provided or omitted.  You should always work with a licensed, insured and reputable glass shop that can assess your specific needs and local building codes and offer professional services. Never attempt to cut, install, or otherwise work with glass yourself. All content is provided on an informational basis only.


Phillip Thompson

By Phillip Thompson

Phillip Thompson is an author for Glass.com


12 responses to “Why Do Windshields Crack?”

  1. Hi I just want to ask about my windscreen,this morning I went to work my screen was fine,I park under cover parking Got to my car at 5 pm.And their was a crack in my windscreen it is on the drivers side and runs up from the bottom about 15cm long.Their was no chip their,could the weather coused it.

  2. I find it interesting that you mentioned that wind gusts can cause stress cracks on a windshield. When you said that, I thought that I should find nearby replacement services for my brother before he leaves on a food trip by car. Doing this will help him get it repaired in case it breaks while he drives over highways at night.

  3. One day I parked my car (TATA NANO) outside , on that evening there was a rainfall, on the next morning the cars rear windshield has seen broken. What might be happened?

    • Hi Sameer,

      Was there any hail or wind also? Wind could have caused a branch to fall on the car or a large ball of hail could have broken the glass. Or it simply could have been a coincidence that it was raining that night. Unfortunately there are many, many possibilities and without more information it is hard to say what caused the breakage.

  4. My windshield cracked and i have no clue why or how. I see a point of impact but nothing has hit it. Ive had it for a week. Its cracked on the driver side at the bottom. Then today again from the point of impact to the passenger side.

  5. Hi,
    My wife, who doesn’t weigh more than 105 lbs, was waiting for in the car while I went to grab something. The seat as reclined and she had her feet up against the windshield, the windshield cracked! This is a 2018 BMW X5, it seems that there must a manufacturing defect and of course the dealership is denying this. Does this seem normal? Doesn’t seem fair to dish out the $1,000. A windshield should be able to withstand such minimal pressure.

    • Hi Chris,
      There are many factors that play a role in this. It could be that the windshield already had minor damage that wasn’t readily observable to the naked eye and the pressure cause the damage to spread. Temperature changes also play a part. It does seem a bit out of the ordinary, but difficult to say whether it is “defective”. There are not currently any open windshield recalls for the 2018 BMW X5, but you can file a complaint with the National Highway Traffic Safety Administration if you feel it is warranted.

  6. if you pull on the mirror and twist it really hard the wrong direction of the design, will that crack the windshield?

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