A cracked windshield will not shatter into pieces the way a side window does. That does not make it safe to ignore. Here is how windshield glass behaves once it is cracked, and when you should stop driving on it.
Why windshields do not shatter
A windshield is laminated: two layers of glass bonded to a plastic interlayer. When it cracks, the interlayer holds the glass together. Side and rear windows are tempered glass, which breaks into small pieces instead.
What a crack does to the windshield
- It keeps spreading. Road shock, potholes and temperature swings make a crack longer, sometimes suddenly.
- It weakens the glass. A second impact on a cracked windshield is more likely to push the glass in.
- It weakens the structure. The windshield helps support the roof in a rollover and backs up the passenger airbag.
- It blocks your view. A crack in the driver’s line of sight can also break your state’s equipment laws.
Stop driving on it and call for service when
- the crack is spreading quickly,
- it has reached the edge of the glass,
- the glass looks pushed in or loose,
- water or wind is coming in, or
- it is in your line of sight.
What to do next
A single crack up to about six inches, not at the edge and outside the driver’s line of sight, can usually be repaired. Anything else means a replacement. Both can be done at our shop or at your location, often the same day.
Not sure if your crack is legal to drive on? See the cracked windshield laws for Michigan, Indiana and Illinois.