After getting a crack in my windshield, I found that I had a lot to learn! Can it be repaired? If so, how quickly must it be repaired? Does insurance cover it? Was the crack due to a defect in the original windshield? Is the replacement going to be the correct one? Is it going to be as good as the original? What do those codes on windshields mean? This information was not easily accessible.
What a Windshield is Made of
A car windshield is made up of two pieces of glass that are separated by a layer of "PVB" (polyvinyl butyrate) that essentially 'glues' the two pieces together. This has several benefits, the most important being that in the event of a crash, it is much more difficult for objects outside a car to get in (or passengers to be ejected from the car), and the windshield is unlikely to break into lots of small pieces. This layer can also help block out harmful UV rays, can add some tinting, and can help reduce the amount of sound that comes through the windshield.
Repair or Replace?
One of the first questions that comes up after a windshield is damaged is whether to repair it or replace it. Originally, damaged windshields had to be replaced. But that was very expensive, so windshield repair became common. In fact, many insurance companies will give you the option of repairing a windshield for free, instead of replacing it (in which case you might have a deductible to pay). Commonly, it is said that if a crack is smaller than 6" long (or smaller than the size of a dollar bill), it can be repaired (and that chips/dings fitting under a credit card can be repaired). There is one company, UltraBond, that has a product that can repair cracks up to 24" long.
Repairing is often desirable because it keeps the original factory installation of the windshield. Repairing also prevents the old windshield from being thrown out, helping the environment.
Cost
Repairing typically costs about $50 for the first chip, plus about $10-$15 per additional chip. Cracks can be more expensive, depending on the length, up to about $100-$150. Replacing a windshield is significantly more expensive; the average price commonly being reported as $350 (but can be well over $1,000 if an OEM windshield is used).
Windshield Markings
Windshields (and other auto glass parts) have a marking that has information about the piece of glass and who manufactured it. Since we couldn't find any good reference out there, we started our own! Feel free to check out our
After getting a crack in my windshield, I found that I had a lot to learn! Can it be repaired? If so, how quickly must it be repaired? Does insurance cover it? Was the crack due to a defect in the original windshield? Is the replacement going to be the correct one? Is it going to be as good as the original? What do those codes on windshields mean? This information was not easily accessible.
Windshield Standards
Automobiles sold in the United States are covered by a series of safety standards called Federal Motor Vehicle Safety Standards (FMVSS). The ones related to windshields are FMVSS #205 ("Glazing Materials") and FMVSS #212 ("Windshield Mounting"). You can find the standards on this site, both FMVSS205 and FMVSS212.
Deductibles
Normally, cracks in windshields are covered under the Comprehensive section of your car insurance policy. That section is usually optional, so there is a chance that you may not have any coverage. If you do have coverage, you probably have a deductible (typically $500). However, some states require no deductible (in which case you pay nothing), and others have lower deductibles (such as Massachusetts, which has a maximum $100 deductible, so the most you could pay is $100).
Driveaway Time
When a windshield is replaced, 1-hour driveaway times are common (meaning that after an hour, you can drive the car, and the windshield is guaranteed to stay in place). However, it can take 8-24 hours for the adhesive to fully dry. This means that in some types of collisions (rollovers or head-on collisions), the windshield could pop off, causing the roof to crush more easily, or airbags not to function properly (as they use the windshield for support).
Crack Types
Typically, cracks occur when a rock or other road debris gets kicked up by a car in front of you, and hits your windshield. This will often result in a "starburst" pattern (small cracks leading away from where the rock hit), or one long crack (most often if the rock hits the edge of the windshield).
Bull's Eye - Damage to glass caused by a rock (or other object) that is circular, typically with a cone in the outer layer of the glass.
Chip - Damage to glass caused by a rock (or other object) that causes a small piece of glass to come off the windshield.
Combination Break - When there are multiple types of breaks in a windshield, such as a chip with cracks coming off of it.
Crack Chip -
Ding - [used by general public]
Edge Crack - A crack that starts within 2" of the edge of the windshield, or reaches the edge of the windshield. It normally forms immediately, and starts at 10-12" long.
Floater Crack - A crack that starts in the middle of the windshield (anywhere that is not within 2" of the edge of the windshield).
Half Moon - Damage to glass caused by a rock (or other object) that is similar to a bull's eye crack, but not completely circular.
Long Crack -
Partial Bulls-Eye - Same as Half Moon.
Pit - [impact point]
Star Break -
Stone Break - A small chip that occurs when a stone (or other hard item) hits the windshield. It can then become a large crack over time.
Stress Crack - A crack that occurs without anything hitting the windshield, typically due to a large variation in the temperature (such as when the car is sitting in the sun, and then you start it and use the air conditioning). It almost always starts at the edge of the windshield. Stress cracks will normally be a straight (or slightly bending) line, and will not have any sign of impact. A "pen test" is often used to determine if there is a stress crack -- a ballpoint pen is run along the crack, and if it dips anywhere, it is not a stress crack. That is because with a stress crack, no glass actually comes off the windshield.
OEM vs. Aftermarket (ARG; Auto Replacement Glass)
OEM (Original Equipment Manufacturer) windshields are created differently than aftermarket ones (aftermarket parts are ones that are sold to replace the original parts of a vehicle). "OEM auto glass standards require 100 percent windshield retention in frontal barrier crash tests, while DOT only requires 80 percent!" [http://ezinearticles.com/?The-Truth-About-OEM-Phoenix-Auto-Glass-Parts&id=474405 "Some aftermarket parts do not match the tolerance, thickness, and shape of OEM auto glass parts; therefore, they can have a higher rate of leakage, wind noise, imperfect fit, solar performance, and optical distortion" [same]. Note that glass "from an OEM manufacturer" is not OEM glass, it's just glass from the same company that made the original part (which may have completely different specs). ARG windshields have higher levels of stress, since manufacturers limit the stress allowable in the OEM windshields they contract for (source).
Interestingly, many state laws allow the use of aftermarket parts, but define them as being either sheet metal or plastic. That implies that the laws do not apply to windshields (despite the term aftermarket applying to non-OEM windshields in standard usage), making interpretation of the laws more difficult.
