Do I have to replace a cracked window?
A car window’s primary purpose is to allow safe and clear vision of all objects around the vehicle while keeping the element out, and to provide security to the passengers and their personal items. Additionally, they provide structural integrity to vehicle; especially the windshield and rear window. Windows help to work with the body lines and improve the overall aerodynamics as well.
With the exception of the windshield, windows are typically made out of tempered glass which usually cracks and then shatters into thousands of pieces. It is possible for windows to get a scratch or chip, like the ones found typically in the windshield, but it is more common for them to shatter.
Since windows are under stress from the body - especially when in the full up position - a crack that does not shatter the window should be addressed as the added stress will inevitably lead to a broken glass. Damage to the body or door can also cause contact of the window with the interior support structure of the door which can lead to damage or cracking.
Windows are also subject to expansion and compression as heat changes, which will flex them and add to the stress. In the case of a windshield, we treat cracks and chips slightly different since this window is actually laminated together. The window is a composite assembly that is multiple layers of glass with basically a plastic filler in the middle to bond them together. While the window can still shatter, the lamination usually keeps the window from throwing pieces all over the vehicle. These windows tend to get more cracks and chips because of their forward facing position traveling into the path of debris thrown up from other vehicles like small rocks and other items on the roadway.
A small chip can often be repaired by a glass specialist, but if the crack or chip is over a large area, extending from top to bottom or side to side or out in a large star pattern then the entire glass should be replaced. If the chip or crack obstructs the driver's clear view of the road in any way, the safest answer is always “When in doubt replace for safety.
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