Car window and windscreen repair

Chip or crack: repair or replace?

A windscreen is laminated: two layers of glass bonded to a clear plastic layer in between. That is why a stone usually leaves a chip rather than a hole, and why a chip can sit there for weeks before a cold morning, a hot day or a pothole turns it into a crack.

Glass repairers look at three things when deciding whether car windscreen repair is possible:

• Size. Small chips and short cracks can usually be filled. Long cracks can’t.
• Position. Damage close to the edge of the glass weakens the whole windscreen, and damage right in front of the driver can affect your view even after a good repair.
• Age and dirt. A fresh chip repairs far better than one packed with grime and water.

Windscreen damage and your WOF

For a WOF, the inspector pays most attention to the area of the windscreen in front of the driver that the wipers clear. Damage there usually means a fail, apart from minor stone marks and properly certified repairs that don’t affect your view. Elsewhere on the glass, damage fails if it is larger than set limits, goes through more than one layer of glass, or stops the wipers working. Chip repairs should meet the standard AS/NZS 2366, so keep the repairer’s receipt as proof.

How chip repair works

The technician cleans out the chip, injects a clear resin under vacuum and cures it with ultraviolet light. The job usually takes well under an hour. A repaired chip may still be faintly visible, but the resin restores strength and stops the damage spreading. Front window chip repair costs a fraction of a new windscreen, so get a chip seen to before it spreads.

When a crack means a new windscreen

Once a crack runs more than a short distance, reaches the edge of the glass or sits in front of the driver, front glass crack repair is rarely an option and the windscreen is replaced. On many newer cars that also means recalibrating the camera mounted behind the glass, which adds to the cost.

Side and rear window repair

Side and rear windows are usually toughened glass rather than laminated. Toughened glass is designed to shatter into small, blunt pieces, so it can’t be repaired. If a side or rear window is broken, it is replaced. Some newer cars use laminated glass in the side windows too, which is quieter and harder to break into but costs more to replace.

Rear windows carry the demister lines, and sometimes the radio aerial, so a replacement includes reconnecting them. Ask the repairer to check that the demister works before you drive away.

When the glass isn’t the problem

Not every car window repair involves new glass. If a window drops into the door, moves slowly or won’t go up, the cause is usually the window regulator, the motor or the switch. A glass repairer or an auto electrician can replace these. Our DIY car fixes guide covers the simple checks to try first.

Car glass repair costs in NZ

The make and model make a big difference. Windscreens with rain sensors, heated glass, a head-up display or an acoustic layer cost more, and cars with a camera behind the glass need recalibrating after a replacement.

Glass cover and insurance claims

If you have comprehensive car insurance, check whether your policy includes glass cover. Many do, and the terms are often better for glass than for other damage:

• Some insurers repair windscreen chips with no excess, because a repair now saves them a replacement later.
• A windscreen replacement may have its own, lower excess, or be covered by an optional glass add-on.
• Your insurer may send you to a preferred glass repairer, but you can usually ask about using another one.
• Third party policies generally don’t pay for damage to your own glass.

Call your insurer or check the policy wording before booking, and keep the invoice either way.

Mobile and 24-hour glass repair

Many glass repairers come to you, so a search for “car glass repair near me” can turn up a technician who works in your driveway or the work car park. Chip repairs and many windscreen replacements can be done on site, as long as the weather is dry, because the resins and adhesives need a dry surface.

After a new windscreen is fitted, the adhesive needs time to set before the car is safe to drive. The technician will tell you how long to wait, so plan for it rather than booking a fitting just before you need the car.

Emergency or 24-hour car window repair is mostly about making a car secure after a break-in or a smashed window: clearing the glass and fitting a temporary cover. The replacement glass is usually fitted the next working day.

Temporary fixes until it’s repaired

• Cover a fresh chip. A piece of clear tape over the chip keeps out water and dirt, which helps the resin bond when it is repaired.
• Go easy on temperature changes. Don’t point the demister or the air con straight at a chipped windscreen on a hot or frosty day, and skip the car wash until it is fixed.
• Avoid home remedies. Superglue or nail polish in a chip makes a proper repair harder.
• Secure a broken side window. Wearing gloves, remove loose glass and vacuum the seats and door channel, then tape heavy plastic over the opening to keep the weather out until it is replaced.

If a crack blocks your view of the road, don’t drive the car until the windscreen has been replaced.