Most windshield cracks start with a small chip. The chip comes from the road; the crack comes from what happens to the glass afterwards. These are the causes we see most often in Michigan, Indiana and Illinois.
Rocks and road debris
Gravel thrown up by trucks, construction zones and freshly salted roads is the most common cause of a chip. Following a truck at highway speed raises the risk.
Temperature swings
A warm cabin against frozen glass, a defroster on full, hot sun followed by cold air conditioning — sudden temperature changes stress the glass around an existing chip until it runs.
Potholes and rough roads
Hard impacts flex the vehicle body and the glass with it. A crack that was stable can grow several inches after one bad pothole.
An old chip that was never repaired
A chip left alone collects dirt and water. In freeze-thaw weather, that water freezes and expands inside the break. This is the most common path from chip to crack.
Stress at the edge of the glass
A crack that starts at the edge with no impact point is a stress crack. Temperature swings, body flex or an installation that left the glass under stress are common reasons.
Slammed doors, hail and falling branches
Slamming a door with the windows closed pushes against the glass. Hail and falling branches cause direct damage.
How to keep a chip from becoming a crack
- Get chips repaired quickly; repair usually takes under 30 minutes.
- Cover a fresh chip with clear tape to keep water and dirt out.
- Warm and cool the cabin gradually.
- Leave more space behind trucks and gravel haulers.