Cracked Windscreens in Cold Weather: What to Do and What to Avoid

Why cold weather makes damage worse

Glass expands and contracts as it warms and cools. When the temperature changes quickly, or unevenly across the screen, different parts of the glass move by different amounts, and that sets up stress. A chip or a small crack is a weak point, so that is where the stress concentrates.

Water can also get into a chip, freeze and expand. Over a few nights of frost, a tiny break can be pushed a little wider each time. This is why a chip that looked harmless in October may have turned into a crack by January.

De-icing mistakes to avoid

The single most common mistake is pouring hot or boiling water on a frozen screen. The sudden change in temperature is exactly the kind of shock a weakened windscreen cannot take, and even an undamaged one can crack. Lukewarm water is better than hot, but a proper de-icer spray and a plastic scraper is the safer route.

Wipers frozen to the glass are another trap. Running them while they are stuck can tear the blades or strain the wiper motor, and a bit of grit trapped under the blade can scratch the glass. Clear the ice first and lift the blades away from the screen.

• Never use boiling or very hot water on a frozen windscreen
• Use a plastic scraper, never a metal one
• Do not turn the wipers on while they are stuck to the glass
• Avoid scraping hard directly over a chip or crack

Using the demister gently

Cranking the heater to full heat and pointing every vent at the screen is a fast way to put thermal stress on damaged glass. A better approach is to start the engine, set the fan to a moderate speed and let the warmth build gradually, using the air conditioning to help clear misting.

If you can, give yourself a few extra minutes in the morning. Rushing the defrost is how most winter cracks start, and the time you save is not worth a new windscreen.

Looking after a chip before it spreads

If you have a chip, get it seen before the cold sets in, or as soon as you notice it. A small, clean chip is far more likely to be suitable for windscreen chip repairs, which fill the damage and help stop it spreading. Left to freeze and thaw, it may grow beyond what a repair can cope with.

Parking out of the wind and away from frost where possible helps. A cover over the screen overnight can keep ice off the glass, which means less scraping and less need for heat in the morning.

• Keep the chip clean and covered with clear tape until it is repaired
• Avoid parking under dripping trees or where water pools
• Treat any new crack as something to be checked, not ignored

When a crack means replacement

A crack that has grown across the glass, reached the edge or runs through your line of sight is usually a case for windscreen replacement. A long crack makes the screen weaker, and if it is in your direct view it is a safety concern as well.

Around Tyneside, winter also means grit on the roads, which flicks up stones and chips the glass, so cold-weather damage is common. At Banks of the Tyne in Hebburn we handle windscreen repairs and replacement, and we will tell you honestly which one your screen needs once we have seen it.

Frequently asked questions