Your Windscreen's Weak Spot Is Showing — Catch It Before the Cold Does

There is a particular kind of UK November morning where the car is frosted, the heater is on full, and the windscreen makes a small ticking sound that you convince yourself is normal. Usually it is. Sometimes it is the sound of a five-quid chip turning into a several-hundred-pound problem.

Windscreen damage is one of those things that feels minor right up until it isn't. A star, a bullseye, a little crescent near the edge — none of them look urgent in mild October weather. Then the temperature drops, the defroster kicks in, and the glass gets asked to do two contradictory things at once. That is when a harmless-looking pit becomes a crack with ambitions.

Start with a proper look, not a glance

Most drivers check their screen the way they check a front tyre: a quick visual sweep while walking to the door. That misses plenty. Clean the outside of the glass, then clean the inside too, because grime on the inner surface can hide a chip from the cabin side. Use a torch at a low angle rather than straight on. Damage that vanishes in daylight often shows up as a bright pinprick when the light skims across it.

Run a fingernail gently over suspect spots. If it catches, you have found a break in the surface. Pay attention to the wiper park area, the edges of the screen and the driver's line of sight. Photograph anything you find with a coin or a fingertip beside it for scale. It sounds fussy, but it gives you a record of the size before the cold gets to work, and that is useful when you speak to an insurer or a glass technician.

Why the first frost is the enemy

Glass does not particularly enjoy rapid temperature swings. A chip creates a tiny stress riser — a point where force concentrates. When you start the car on a freezing morning and aim a hot blower at a cold screen, the glass expands unevenly around that weak spot. Add a pothole, a speed hump or the sort of torsional twist a car gets when one wheel drops off a kerb, and the chip has every excuse it needs to run.

This is why a repair that would have been straightforward in September can become a replacement in December. It is also why pouring boiling water on a frosted screen is such a bad idea. The thermal shock can crack healthy glass, never mind damaged glass. Use a proper de-icer, let the car's own demister do its job gradually, and keep the blower on a moderate setting for the first few minutes rather than going straight to max heat.

What a DIY kit can and cannot fix

Resin repair kits are widely available for around a tenner to twenty pounds, and some of them are genuinely useful. They work best on small, clean, round impacts — a bullseye or a simple star — where the damage has not spread and moisture has not worked its way in. The idea is to push resin into the break, cure it with UV light, and stabilise the glass so it stops propagating.

What they cannot do is make a complex break disappear, restore strength to a crack that is already running, or deal safely with damage in the driver's central field of vision. Edge damage is another no-go area; the edge of a windscreen is under different stresses, and a repair there is far less reliable. If the chip has legs radiating into the driver's line of sight, or if you can see a dark shadow under the glass suggesting dirt or moisture has got in, a kit is not the answer.

A DIY repair can buy you time and reduce the visual annoyance. It should not be treated as a permanent fix for anything beyond a simple, small impact. If in doubt, get a professional opinion before you start poking resin into it.

The insurance conversation worth having

If you have comprehensive cover, windscreen glass is usually included. Repair is often free or the excess is waived, because insurers would much rather pay for a resin repair than a full replacement. Replacement excesses commonly sit somewhere between £75 and £150, but the headline figure is not the whole story. Modern cars often have cameras and sensors mounted behind the screen, and a replacement can require recalibration of those systems. That is one of the reasons a job that sounds like a simple glass swap can climb towards £600 or more on some vehicles.

Use your insurer's approved glass partner and ask specifically whether the damage is repairable. If you are being steered towards a replacement, it is fair to ask why. Is the damage in the driver's primary vision zone? Is it beyond the size the repair standard allows? Has moisture compromised the break? A good technician will explain. A call centre reading a script may not.

Do not wait until the morning of an MOT to deal with it, either. Damage in the driver's central line of sight can be an MOT issue, and it can also be a safety issue when low winter sun is bouncing off a cracked screen. A repair appointment is much easier to arrange than a failed test and a same-day replacement.

A small prevention plan

Keep an eye on the screen through autumn and winter, especially after cold snaps and after any encounter with a gritter. Fix chips while they are still chips. Warm the car gradually. Avoid slamming doors with all the windows shut when the glass is frozen, which adds a unnecessary pressure pulse. And if a repair is legitimate, do not let yourself be talked into a replacement purely because it is quicker to sell.

A windscreen chip is not a crisis. It is a small piece of maintenance that becomes a large piece of expense if you ignore it. Ten minutes with a torch now is a lot cheaper than a crack that decides to travel the width of the screen on the first properly cold morning.