Stress Cracks – What Are They?

Stress Cracks – What Are They?

There are many different types of windscreen cracks, most of which happen when an object hits the glass.

However, many people aren’t aware that there’s actually another type of crack which occurs without anything impacting the windscreen.   This is called a stress crack and whilst it may seem that these occur spontaneously, there is always an underlying reason why they happen.

Just as humans get stress fractures which are caused by repetitive force, overuse or regular use of a bone that has been weakened by a condition like osteoporosis, a stress crack on a vehicle’s windscreen is generally caused by significant variations in temperature or pressure or it may be as a result of a structural defect.

How do I know it’s a stress crack?

Apart from the fact that the crack has appeared without any rhyme or reason, getting an expert opinion from a professional autoglass repairer is the only way that you can make a positive identification and get advice on whether it’s possible to fix it.

No glass actually comes off the windscreen in the event of a stress fracture so there is no physical sign of impact, and the crack is generally in a straight or slightly bent line.

 Where are stress cracks found?

A stress crack will usually start from the edge of the windscreen.   It can quickly become quite large, particularly if it is subjected to temperature fluctuations and if the vehicle is driven on uneven road surfaces which can cause vibrations.

What causes a stress crack?

Pressure changes, structural defects or weaknesses and severe temperature changes are the three main causes of stress cracks.

For example, pressure change from an explosion can lead to a stress crack even if the vehicle is parked kilometres away from the blast zone.

Structural weaknesses can result from manufacturing defects, such as residual stress along the perimeter of the windscreen which occurs during the annealing (heating and cooling) process of the windscreen glass.   If the windscreen hasn’t been installed correctly or isn’t good quality, or if the actual structure of your vehicle (like the roof, the air bags, the dashboard) aren’t in a good condition, then your autoglass may be at risk of residual stress.

Temperature changes (even just between day and night) or more severe ones like washing the windscreen with cold water on an extremely  hot day or using hot water to melt ice or snow in wintery weather can cause stress cracks.

What to do

A stress crack is serious and because they can spread quickly, they can become a real safety hazard in no time.  There’s the risk that they may spread and obstruct the driver’s vision or they may even cause the glass to shatter, so it is imperative that you have the windscreen repaired or if necessary, replaced as soon as possible.

How much does it cost to repair a stress crack?

Fixing a chip or crack in a windscreen is generally a very simple process and can be done on site quickly and cost-effectively.  However, it does depend on the location and the severity of the problem and because a stress crack usually starts from the edge of the windscreen and worsens quite quickly, often impacting on the driver’s line of sight, it can be difficult to repair.  A full windscreen replacement may be necessary.

However, a windscreen replacement can also be a quick and simple process and if you contact Autoscreens, leaders in windscreen repairs and replacements in Perth, they will respond immediately to get you safely back on the road in no time.  They cover all areas in Perth and will come to your home or workplace at your convenience.

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