The quick answer is not a blanket Yes or a No. you will need to consider a few questions such as is it a chip or a crack, the size of the crack and how long is it, how deep is the crack and are there multiple chips or cracks, and where is the crack located.
If a rock or another object bounces and chips, or creates a divot, in the windshield and if the chip or divot occurs as a surface chip on the windshield and if it does not penetrate to the second layer of the windshield, then it could likely be repaired saving hundreds of dollars.
A crack is very different from a chip. A crack in the windshield is a separation of the glass, itself. The windshield is made up of three layers which include two outside layers of glass with a middle layer of polyvinyl butyrate (PBV). PBV acts as a protective layer against shattering upon an impact. Any breach (chip or crack) in these layers, no matter how small, compromises the integrity of the entire windshield and must be repaired or, depending on how deep the chip or crack is, how long is the crack, are there multiple chips or cracks, and where the chip or crack is located, may warrant the windshield needing replacement. A chip is the beginning of a crack. A crack will grow or spread in length due to weather and temperature variances, road conditions such as potholes, speed bumps, and changes in the regularities of the roads. All these stressors on the vehicle directly impacts the windshield causing a worsening of the crack. A good rule of thumb to use to determine if a crack is able to be repaired or if the windshield needs replacing, is to measure the length of the crack and look for it to be under 5 inches in length and less than one-third of an inch deep. If the crack or chip, measuring less than three-quarter of an inch in diameter, is less than one-third of an inch deep, then it likely did not penetrate all the way to the second layer and can be repaired. However, there could be multiple cracking offshoots from the original chip that run in different directions, not just horizontally. If this is the case, the repair adhesive may fail or not cover all the offshoots, making an extended secondary crack likely. An auto glass company or body shop will be able to assess it and tell you if a repair is sufficient rather than an entire windshield replacement.
If, however, the crack is longer, say 12 inches, and is a surface crack only, then Yes it is likely it can be repaired. Keep in mind, this is not a Do – It – Yourself project. Call Apex Auto Glass to assess the damage. If the depth of the crack has penetrated to the second or third layer of the windshield, then No, it cannot be repaired and the windshield will need to be replaced. This is true with any size crack or chip.
Where the crack is located is another factor to consider. If the 12-inch crack, shorter or longer, has creeped into the sides of the windshield, then damage to the perimeter seal is likely and, err on the side of safety and choose to replace the windshield rather than attempt to repair it. The seal between the glass and the windshield frame has been breached and is unsafe. Also, if it reaches the outer perimeter of the windshield to the frame, then it has also breached the embedded antenna and heating or defrost elements. This breach will make this an unrepairable crack and will require replacement.
So to answer the original question of “can a 12-inch long crack be repaired”? It really is a Yes or No answer. The answer depends on several factors to consider which are location, how deep is the crack, and are there multiple chips or cracks as offshoots of the original chip.
The bottom line is this: the minute you notice a chip or crack in your windshield, no matter how small, call Apex Auto Glass to have its depth assessed. The naked eye cannot determine if the chip or crack has penetrated to the second or third layer of the glass. Also, if repairable, have it repaired as soon as possible. Cracks begin from chips. If it’s a chip, repair it. If it’s a crack and able to be repaired, repair it as soon as possible to avoid the crack creeping and growing longer.