What to Do If You Get a Stone Chip in Your Windscreen

That sharp crack of a stone hitting the glass is a sound every driver knows. Look closely and you will usually find a small chip, often no bigger than a lentil. Most chips like that can be filled with a stone chip repair in about 20 to 30 minutes. The catch is that they do not stay small for long, which is why the first few days matter.

What to Do as Soon as You Spot a Chip

1. Cover it with clear tape. A small piece over the chip keeps out dirt and water, and a clean, dry chip takes the resin far better.
2. Note where it is and how big it is. Check whether it sits in front of the driver, and hold a coin next to it to judge the size. The MOT rules below explain why both matter.
3. Go easy on the glass. Keep the heater and air conditioning from blowing straight at the screen on full, skip the car wash and close the doors gently.
4. Book the repair. A few days can be the difference between a repair and a new windscreen.

Why a Small Chip Turns Into a Crack

A windscreen is two layers of glass bonded to a clear plastic layer in the middle. When a stone breaks the outer layer, the chip becomes a weak point. Temperature swings put it under stress: a frosty morning followed by the heater on full, or a car parked in the sun and then rinsed with cold water. Potholes, speed bumps and slammed doors add vibration. Any of these can send a crack running from the chip across the screen, and once that happens a repair is usually off the table and you will need a new windscreen.

How the MOT Judges Windscreen Damage

MOT testers use a template that splits the screen into two zones within the area the wipers clear. The full rules are in the MOT inspection manual on GOV.UK.

• Zone A is a strip 290 mm wide, centred on the steering wheel. Damage larger than 10 mm across here fails the MOT.
• Zone B is the rest of the swept area. Damage larger than 40 mm here fails.

Which Chips Can Be Repaired?

• Chips roughly the size of a 5p coin or smaller.
• In zone A, right in front of the driver, chips up to 10 mm across. A repair there can leave a faint mark in your line of sight, so we talk it through with you before we start.
• Chips that have not yet spread into a crack.
• Chips a few centimetres or more from the edge of the screen, where damage tends to spread quickly.
• One or two chips on the same screen. With more than two, we recommend a new windscreen instead.

Should You Try a DIY Repair Kit?

Repair kits from car parts shops are cheap, but they are hard to get right on a chip you cannot see inside. If air or moisture is still in the chip when the resin sets, it is sealed in, and the chip usually cannot be filled properly afterwards. A chip that could have been repaired may then need a new windscreen, so if you are unsure, keep it taped and leave the filling to us.

How a Repair Seals the Chip

In short, the chip is cleaned and dried, filled with resin under pressure and set hard with UV light, then polished level with the glass. The result is a sealed repair that makes the chip much harder to see, though it may still leave a faint mark. Our stone chip repair page goes through the visit step by step.

How to Lower the Risk of Another Chip

• Leave a bigger gap behind lorries and tippers, especially on roads that have just been resurfaced, where loose chippings get thrown up.
• On frosty mornings, let the demister clear the ice rather than reaching for hot water, which can turn an old chip into a crack.
• Look over the screen when you wash the car, so a new chip is found while it is still small.

Not Sure If Yours Can Be Saved?

Send a photo of the chip with the coin beside it to our WhatsApp on 07426 801611 and we will tell you whether it can be repaired. If it can, we will have a technician with you within 24 hours.