Judging the Size of the Crack: How to Know You’re in Need of a Windshield Repair

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Repairing a Cracked Windshield in Mississauga

A windshield in good condition makes your car look great, but it also has an important safety purpose. The windshield protects you from rocks and any other objects sent flying on the road, and also from dust and suspended particles. These might not seem like a threat, but even a small object is very dangerous when you’re moving at high speed.

Actually, a windshield is made of two glass layers separated by a plastic layer. A single glass pane would be more likely to break completely when struck by an object, but this two-layer design is much more resistant. When only the external layer is damaged and the affected area is small, you can often get the windshield repaired without needing a full replacement.

Driving with a damaged windshield is very dangerous, and the risks often get underestimated. A windshield with cracks is weaker, and less likely to protect you from another impact. Also, if the damage is located right in front of the driver’s seat, it affects visibility and accidents are more likely. In some places, you might even get a ticket for driving with a damaged windshield. If you are driving a vehicle as part of your job, you should always conduct a pre-trip inspection of the vehicle, including the windshield.

Should I repair or replace my windshield?

Only a qualified auto glass technician can determine if your windshield can be repaired after an impact, or if you need a full replacement. However, the Auto Glass Safety Council has developed the Repair of Laminated Automotive Glass Standard (ROLAGS), which provides guidelines to determine what types of damage can be repaired.

  • Bullseye impact: Diameter up to one inch or 25 mm
  • Combination break: Diameter up to 2 in or 50 mm
  • Windshield crack: Length up to 14 in or 350 mm
  • Half-moon or partial bullseye: Diameter up to one inch or 25 mm
  • Star break: Diameter up to 3 in or 75 mm
  • Surface pit: Diameter at least 1/8 in or 3 mm

We must keep in mind these are just guidelines, and this information should not replace a professional windshield inspection. Some cracks may start small, but they can grow due to temperature changes and the constant vibration produced by the engine. The best recommendation is getting your windshield checked as soon as possible, before the damage has a chance to spread. Sometimes the extent of the damage is too severe, or its location makes it hard to repair.

Here are four cases where you will need a new windshield:

1) Deep cracks that go through the windshield

Generally, a windshield crack can be repaired when it’s superficial and small. However, when the damage has reached the intermediate plastic layer and the inner glass layer, you will need a full replacement. Keep in mind your windshield has a protective function, and deep cracks can greatly reduce its strength.

You will also need a replacement if your windshield has been damaged from the inside, since this also reduces its protective function.

2) Cracks on the corners of your windshield

Corner cracks are very dangerous, and auto repair technicians will normally recommend a new windshield if this happens. There are two main reasons why a full replacement is the best solution in this case: a corner crack makes your windshield unstable, and it’s more likely to shatter completely with the next impact.

3) Multiple cracks or impacts on your windshield

A windshield is more vulnerable when there are several previous impacts on its surface, even if they are small. Each impact makes your windshield weaker, reaching a point where the next one can shatter it completely. In other words, the windshield loses its protective function, and flying objects are more likely to hit the driver or passengers.

4) Windshield damage right in front of the driver

As mentioned in the ROLAGS, there are many cases where windshield damage can be repaired, saving you the cost of a replacement. However, when the crack or impact is in the driver’s line of sight, you might need a new windshield even if the damage is small.

Windshield repairs often leave marks, and this is not an issue when they are out of sight. However, a mark right in front of the driver can affect visibility of the road and other cars, and this is an issue when you need to respond fast to avoid an accident.


Your windshield is a part of your car’s design, but also a protective feature. Minor damage can generally be repaired, but large cracks and impacts normally mean you need a new windshield. There are also specific cases where a replacement is recommended, even if the damage is small: deep cracks, corner cracks, multiple smaller impacts, and any damage that leaves a mark in front of the driver.
BIS Safety Software is a learning & compliance company. Since 2006, BIS has been providing software perfectly suited to the safety professional to help them and their companies meet their safety training needs, as well as manage their entire safety program.

If you are located in Barrie, there are plenty of windshield replacement companies in Barrie, Ontario, but North Auto Glass is one that can be of great assistance to you.

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