Is It Safe to Drive With a Cracked Windshield?

Hey folks! This is John from Freedom Auto Glass LLC.

Welcome to another Q&A session where I answer questions from you all on the internet.

Today's question is:

"Is It Safe to Drive With a Cracked Windshield?"

Summary:

John gives a nuanced answer, noting that safety depends on the vehicle. On many German cars, the windshield is built into the vehicle's structure and is designed to help during a single rollover, keeping the roof from caving in for that one impact. American cars rely less on the windshield because of heavier structural metal. He dispels a common fear: a cracked windshield will not suddenly cave in, because it is two laminated layers of glass bonded with plastic in the middle, allowing it to withstand multiple hits — he says it could be struck with a baseball bat without falling in. A quality windshield won't shatter. Still, he treats it as a safety issue and recommends replacement, while acknowledging it's case by case and the customer's decision. He adds that German cars often use a stiffer urethane adhesive because the glass does more structural work.

Answer:

That's a tough one, and the honest answer is it depends on the car. On a lot of German cars especially, the windshield is actually built into the structure of the vehicle — it's designed to help in one rollover, to keep the roof from caving in for that one impact. After that single impact it's done, but it does serve a real safety purpose. American cars tend to rely less on the windshield for that, because they've got more thick, heavy metal in the structure. The German cars are sportier, and the glass is genuinely part of how the vehicle holds together. A lot of people think that once a windshield cracks it's going to suddenly fall in on them, but that's not how it works — it's two pieces of glass laminated together with a layer of plastic in the middle, so it can take multiple hits. You could honestly beat on it with a baseball bat and it's not going to fall in on you. A good windshield isn't going to shatter. That said, it is always a safety issue, so I do recommend getting it replaced — but it's case by case, and ultimately it's up to the customer. One more detail on those German cars: the urethane, the glue, is actually stiffer on a lot of them. They use less glue and it's a stiffer formula — you see that on Volkswagens, Mercedes, that kind of thing — because the glass is doing more structural work.