Auto Glass Replacement: The Difference Between Windshield Glass and Side Window Glass

Have you ever wondered what the difference is between my windshield glass and the other glass in your car?

Unless you’re glass nerds like us, probably not. 

But, today we’re going to educate you on the difference and why it’s really important to know the difference. 

The difference between windshield glass and the other glass in my car

Safety glass is used in all automobile glass. 

It’s manufactured to reduce the likelihood of injury if it breaks. Windshields are made from a lamination process, and the windshield glass in your car is made of laminated glass, which is designed to offer the highest levels of safety in the event of a crash. 

Laminated glass is made up of two pieces of glass, with a thin layer of vinyl between them. The three pieces are laminated together by applying heat and pressure in a special oven called an autoclave

When a small object strikes a piece of safety glass, typically only the outer layer of the windshield that is struck breaks. And in severe impact situations, the glass “shatters” but usually does not fly apart because the broken pieces of glass generally adhere to the vinyl inner lining.

Your side and rear windows are made of tempered glass. This is glass produced by heating the glass to more than 1,100°F, then rapidly cooling it. This “tempering” process makes the glass many times stronger than un-tempered glass of the same thickness. 

If broken, tempered glass is designed to disintegrate into small pieces of glass about the size of rock salt. There should be no large, jagged pieces of glass to injure the driver or passengers.

Every part on a new car, comes from the original equipment manufacturer (OEM), including the windshield. This glass meets the original specifications for safety and quality as the glass that it came with from the factory.

Windshields may look simple, but they are actually made from two pieces of glass that are bent in a very precise way. If a windshield does not meet the exact specifications of the manufacturer, it will not fit precisely in your car.

The best way to assure exact fit is to use a windshield produced from a fixture engineered to manufacturer’s specifications. OEM glass is your assurance that this has occurred.

Tempered vs Layered Glass

Wondering what type of glass window is best for your vehicle, if and when you need it replaced?

Here’s what you need to know about tempered and laminated glass.

Tempered Glass

Tempered glass, also known as toughened glass, is created by heating and rapidly cooling a pre-cut standard piece of glass in a tempering furnace. The pre-cut and edged piece of glass is heated up to around 1200°F. After being heated up; the glass is then cooled rapidly. This process is known as quenching.

Quenching produces a hardened piece of glass that is four to five times stronger than before the tempering process. The final product tempered glass is harder to break. Tempered glass is most commonly used for passengers windows on cars while laminated glass makes up your front and rear windshield most of the time. When tempered glass breaks, it is designed to shatter into small pieces that are less likely to cause added injury or damage.

Tempered glass can also be treated with chemicals and thermal treatments; these treatments help give the piece of glass more balanced internal stress capabilities.

Laminated Glass

Laminated glass is created by bonding multiple layers of glass together while under pressure and heat, with a resin called polyvinyl butyral (PVB.) This process creates single sheets of glass that have multiple layers. The PVB produces high sound insulation and helps keep the glass from breaking apart easily. Before shattering, laminated glass will bend and flex. 

Despite not being as strong as tempered glass, laminated glass blocks around 99 percent of ultraviolet light transmission.


Laminated glass is on average more expensive than tempered glass. Until recently, laminated glazings used to cost three to four times as tempered glass. Car manufacturers are required to use laminated glass for windshields. More and more companies are starting to use laminated glass for side and rear windows.

Regardless of your preference of glass window for your vehicle, one company that can fix any kind of windshield is City Auto Glass, where we make auto glass repair easy.