There are many reasons why windshield damage is a problem that requires immediate attention. Most importantly, your car's windshield is an important part of its structure. A severely compromised windshield can reduce the overall integrity of your vehicle, making it potentially more dangerous during collisions.
However, there are also less dramatic reasons why you shouldn't ignore damage to your windshield. Surprisingly, one of these reasons may be the potential for leaks to develop, especially if you ignore the problem long enough for large cracks to form.
Understanding Automotive Windshield Glass
Automotive windshields use laminated glass. Laminated glass comes in a few different forms but always involves two outer layers of glass with an inner resin or plastic layer sandwiched in between. Windshields typically use a material called polyvinyl butyral (PVB) as the inner layer. This design increases windshield strength, prevents dangerous shattering, and helps the glass distribute collision forces.
Because windshields use two layers of glass, it's rare for a single impact to cause a leak. When you see a chip on your windshield after taking a hit from some road debris, there's a high likelihood the damage is purely on the outer layer. In most cases, chips will fail to penetrate the PVB layer, leaving your windshield safe from air and water leaks.
However, cracks can be a more severe issue. Cracks usually form due to stresses on the glass, but a pre-existing chip is often the catalyst. The chip can weaken the glass, making it more prone to cracking due to vibrations, temperature fluctuations, or other disturbances. These cracks may be more likely to penetrate past the laminate or even form on the internal glass layer.
Why Windshield Cracks Are Dangerous
Windshield cracks are typically far more dangerous than chips for numerous reasons. Cracks that fully penetrate the inner glass layer can create air and water leaks, but the risks don't stop there. Where a chip generally won't affect the structure of the glass too severely, a large crack can greatly diminish the ability of your windshield to absorb collision forces.
Cracks will also grow over time as your windshield experiences the normal stresses of driving on imperfect roads and undergoing temperature fluctuations. The longer you ignore the problem, the more challenging it will be to repair and the greater the likelihood that it will require a full replacement. Cracks that reach the edge of the glass may even create new leaks around the trim.
In general, you should treat any crack on your windshield as a worst-case scenario. It's always better to schedule a repair when you first notice a chip before a crack can form. If you can see a crack beginning to develop, contact an auto glass repair company so that you can avoid leaks and have a chance to save your windshield.