A critical feature of a car windscreen is that it will keep itself together following an accident, impact or crash, which helps to prevent serious injuries caused by flying glass.

Whilst such an impact will still require a replacement windscreen to be installed very quickly for safety and legal reasons, this protection in the immediate wake of a car accident can help to minimise cuts, abrasions and other damage caused by glass breakage.

It also stops you from being thrown out of the car, which provides additional protection alongside a seatbelt.

This explains why the law is so serious about windscreens, but it does not necessarily explain how windscreens keep together in the first place.

What Keeps Windscreens In Place Following An Impact?

Windscreens are made from tempered, laminated glass, which makes them much stronger, less likely to break apart, causes them to break into small, harmless pieces rather than sharp shards and holds all of the pieces in place to stop them flying around.

Whilst the composition of windshields can vary, they tend to consist of two tempered glass layers with a layer of polyvinyl butyral (PVB), with each layer providing a particular protective purpose:

• The outer layer is designed to resist scratches, has UV resistance, is weather-resistant and is strong enough to protect the occupants of the car from debris that lands on it.
• The PVB interlayer absorbs the energy of impacts and spreads it around the whole of the windscreen, preventing it from breaking and holding the pieces together if it does.
• The inner layer maintains the structural integrity of the windscreen, meaning that passengers will not be thrown from the car and the roof will hold together if the car rolls over.

All of this also helps to ensure that other safety features such as inertia reel seatbelts and airbags deploy properly.