By law, if the damaged area is within the direct line of sight of the driver, the windshield must be replaced. Also, a repair should be considered only if the damage affects the top layer of glass. If the damage has affected the PVB layer, then the windshield should be replaced, as this would cause the structural integrity of your windshield to be compromised.

In the event of a collision, the glass may break; however, the thin layer of adhesive plastic in the middle will keep it together. This serves a dual purpose. First, the adhesive will prevent the majority of the glass from shattering and causing cuts and scratches to the occupants. Secondly, it allows the windshield to provide somewhat of a cushion to the passengers, should they strike the windshield. The polyvinyl butyrate is flexible, reducing the amount of force exerted to the occupants upon impact with the windshield. This is why windshields are constructed from glass the way that they are, rather than being constructed from plastic. Plastic does not provide the same amount of flexibility and cushion during an accident.

It is well known that seatbelts and airbags are dependent upon one another in order to provide full support in the event of an accident. Additionally, most of your vehicle’s safety features are also dependent upon the windshield. For example, the windshield provides support for your vehicle’s airbags (the passenger airbag in particular). Without this support, the airbag would be incapable of being fully deployed and any protection the airbag was meant to provide would be compromised. Alternatively, the windshield plays a major role in the structural integrity of your vehicles passenger compartment, especially in the event of a rollover. If the windshield is unstable, it may very well fail in the event of a rollover accident, causing the passenger compartment to fall in on itself, putting the vehicle’s occupants at extreme risk of injury or death.

Replaced windshields must be perfectly positioned and installed as to not compromise the integrity of the vehicle’s cab. The windshield provides essential support to the passenger compartment in the event of an accident, especially in rollovers. Think of the windshield as the keystone of an arch.

During a windshield repair, the technician uses a specially formulated resin, injecting it into the damaged area of the glass. The resin is then cured, restoring the windshield’s integrity, and polished to restore the clarity of the glass. If the windshield has become damaged to the point where the PVB layer is compromised, repair should not be considered and complete replacement is required.

The PVB film keeps the glass from shattering in the event of an accident. On impact, most of the glass is kept from entering the vehicle’s cabin, and can even act as a retainer to keep objects, including you, inside the vehicle.

Be sure the windshield is perfectly centered on the vehicle. A misplaced windshield will not provide a structurally sound passenger compartment in the event of a collision or rollover. Also inspect the weather stripping to ensure it fits tightly against the vehicle’s body with no bumps, waves, or gaps. If the replacement windshield on your vehicle is not completely bonded to the vehicle, the windshield may become detached in the event of an accident, leading to even greater chance of serious injury or death.

Most importantly, if the windshield’s inner layer of polyvinyl butyrate has been affected in any way, the windshield should be completely replaced. This adhesive layer is the most important aspect of any vehicle’s windshield, and is what keeps the windshield from shattering into many pieces when impacted.