It's not uncommon for drivers to wonder when it might be time for windshield replacement or repair work on their vehicles. While modern auto glass is much safer than it was a few decades ago, there still comes a point where a damaged windshield will be more than a nuisance. Take a look at when the time might come for a windshield repair and replacement technician to check out your ride.
The size of the affected area is important to monitor. Older NWRA standards assume a windshield must be replaced once a crack is longer than 14 inches or wider than three. Proposed newer standards set that at just 6 inches from the center of wherever the damage occurred. Bear in mind that doesn't mean anything smaller than that is repairable. Some types of damage can present problems even if they're small, especially anything with concentric rings or deep pitting.
Growth Matters, Too
Any crack or pit that continues to grow after the damage occurred is bad news. There is a risk the growth could continue until air pressure against the windshield cause it to cave. Contact a windshield replacement technician as soon as you see evidence a damaged area is increasing in size.
Particularly, you don't want to see any damage within your line of sight if you're the driver. To ballpark where your line of sight is, simply draw imaginary straight lines up from the sides of your steering wheel to the top of the windshield. Anything in the space you've defined is your line of sight. Even a minor chip can be problematic in this zone. Don't assume it can be filled and smoothed out because there is always a risk of distortion. You can't afford to have any distortion in this zone because your ability to read and recognize things doesn't have to be impaired much when you're traveling at highway speeds.
Building up multiple areas of damage is not uncommon, especially for folks who live in regions with lots of gravel roads or vehicles hauling materials. Once you've accumulated more than three spots with chips or cracks, you should consider replacing the windshield. This includes spots that were previously repaired. Similarly, you should consider replacing any windshield that has experienced hazing or distortion due to heat or chemical exposure. If you're unsure, it's best to err on the side of caution and replace the windshield.