Why Did My Car Window Shatter?

image of a shattered car window

Did your car window shatter recently? Car windows can shatter for no apparent reason or due to thermal contraction/expansion stresses. It is also caused by manufacturing defects and “object hits.” However, the spontaneous shattering of a car window can be unnerving. This is especially unnerving if it happens while you are driving. In fact, a shattering vehicle window can make a “pop” sound similar to a gunshot. Below is some more information on this topic.

Explore Our Auto Glass Services Call To Schedule A Free Estimate

An Overview

Modern autos are fitted with either laminated or tempered/toughened glass windows. Laminated auto glass consists of a polyvinyl butyral (PVB) plastic sheet sandwiched between two pieces of glass. These elements are then subjected to intense pressure and heat, thereby strengthening the auto glass. In the event of damage, the shattered glass pieces stick to the PVB sheet instead of flying in different directions and potentially injuring the occupants of a car. On the other hand, tempered/toughened auto glass typically undergoes a special heating and cooling process during manufacturing that enhances its toughness by five to 10 times, the American Physical Society (APS) explains. After sustaining damage, tempered auto glass shatters into tiny pieces instead of jagged splinters that could injure vehicle occupants.

Why A Car Window Shatters

Below, we share some of the common reasons that car windows shatter when they break.

Make An Appointment: (610) 377-7787

Internal Glass Defects With Your Auto Glass

image of mistakes depicting auto glass repair mistakes

Internal auto glass defects such as nickel sulfide inclusions or “stones” can cause car windows to shatter spontaneously. According to the Glass Education Center, nickel sulfide stone defects mostly form in the center tension zone of auto glass during tempering processes. Over time, such stones grow in size due to exposure to temperature differences and eventually cause shattering of the defective car window. Unfortunately, identifying such a car window defect with the naked eye can be extremely difficult because nickel sulfide stones tend to be microscopic, ranging from 0.003 to 0.015 inches in diameter. To prevent this from happening, the American Society for Testing and Materials (ASTM) has published guidelines requiring car manufacturers to ensure that the diameter of internal defects including nickel sulfide stones is between 0.020 and 0.100 of an inch.

Learn More About Our Auto Glass Services Call To Schedule A Free Consultation

The Car WIndow Has Thickness Issues

shattered windshield

Car windows that are not thick enough are likely to shatter even when subjected to minimal vibration (experienced while driving on smooth surfaces). For this reason, you should be extremely careful when replacing your car’s original windows to avoid ending up with low quality windows.

Pre-Existing Damage With Your Car Glass

Pre-existing auto glass damage could worsen over time leading to spontaneous shattering of car windows. For instance, a chipped window or a cracked windshield that occurs on the edge of a car window could spread over time until it causes the entire window to shatter. For this reason, you should ensure your car undergoes auto glass repair as soon as possible to prevent such an outcome.

Vandalism & Car Windows

Vandalism that involves hitting car windows could cause them to shatter. Remember tempering processes only strengthen auto glass up to a certain degree meaning they are prone to shattering when hit forcefully with sharp or blunt objects.

Read Our Reviews



Some of the factors that might cause car windows to shatter include vandalism, internal glass defects such as nickel sulfide inclusions, thickness issues, and worsening of pre-existing damage. Your auto glass is an important mechanism for the safety of you and your car’s passengers. It keeps you safe in the event that an accident was to occur. This is why it is crucial to repair your auto glass as soon as you notice that there is a crack or chip in it.

Call To Book An Appointment


Call Liberty AutoGlass For All Of Your Auto Glass Needs


If you have a damaged windshield or any auto glass needs, be sure to address it immediately. Liberty AutoGlass will be able to repair your windshield quickly while using the highest quality materials. You can rest assured that you and your passengers are safe when using our services. All of our auto glass services are affordably priced and we perform them in a time-efficient manner.

Be sure to check out our windshield replacements and other auto glass services that we offer. This includes back glass, door glass, vent glass, and quarter glass repair and replacement services. Liberty AutoGlass also offers mobile services where we come to you. This way, your day will not be interrupted by having to come to the shop and wait while getting your auto glass repaired or replaced. We back all of our work with a guarantee.

Contact us today or give us a call at (610) 377-7787 or (877) 90-GLASS if you have any questions. Click here to view our complete mobile auto glass service area in Pennsylvania.

Call Now: (610) 377-7787 Read Our Reviews

Liberty Auto Glass credentials