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Rules of the Road

Can You Drive With a Cracked Windscreen?

February 13, 2024

6 min read

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Leon McKenzie

Content Writer

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cracked car windscreen

They protect from the elements, aid visibility, and form an essential part of your vehicle’s structure. But windscreens are also a barrier against debris: stones flying up from the vehicle in front; splintered metal in the event of a crash; and birds or deer careering into your path.

So, when your windscreen gets a chip or crack, it's really just doing its job. But in that moment, as you hear the sharp tap on the glass — and afterwards, when you observe the damage — it probably won’t feel like that.

If the chip is a small one on the edges of your windscreen, you might even be tempted to leave it as it is. But that would be a mistake. Here we take a deep dive into the rules about driving with a cracked windscreen, how to get a chip fixed — and in what circumstances even a small imperfection can result in a failed MOT.

Are chips or cracks in your windscreen dangerous?

crashed car against tree

Depending on the location of the chip or crack in your windscreen, it may obscure your vision and reduce your ability to spot hazards. You might also find it increases glare, making it difficult to see properly when faced with headlights or bright sunshine.

As if that's not enough, chips or cracks weaken the glass, meaning it may not provide protection in an accident. Airbags are deployed in around half a second and rely on your windscreen to push them into the right place (your face, if they work properly). But if your windscreen is weakened, it may not be able to withstand the force of the airbag as it expands — putting you and your front passenger in danger.

And if you’re ever in the position where your vehicle rolls, your windscreen's fortitude is one of the key components that'll help keep you safe. It provides structural integrity that can stop your roof from collapsing inwards, and gives you a better chance of walking away from the crash in one piece.

Is it illegal to drive with a cracked windscreen in the UK?

In certain circumstances, driving with a cracked windscreen is illegal. UK law says that you’re not allowed to drive a motor vehicle in a dangerous condition — described as one that 'involves a danger of injury to any person' (Section 40(a) of the Road Traffic Act 1988). A cracked windscreen could qualify as 'dangerous' if it interferes with the driver's vision.

The Highway Code backs up this message, encouraging drivers to keep their windscreens safe and clear from dirt:

“windscreens and windows MUST be kept clean and free from obstructions to vision”

The use of the word MUST indicates that there is a legal requirement to follow the rule. In this case, it refers to the Road Vehicles (Construction and Use) Regulations 1986. Section 30(3) reads:

“All glass or other transparent material fitted to a motor vehicle shall be maintained in such condition that it does not obscure the vision of the driver while the vehicle is being driven on a road.”

So, a small chip near the very edges of the glass may not see you fall foul of the rules. But if you’re spotted with a crack in the middle right-hand side of your windscreen, you could find yourself in legal mud.

The MOT rules (which we go into in more detail below) prohibit chips of 10mm or greater in the area in front of your steering wheel, or 40mm elsewhere. These are likely to be the measurements used by police to determine whether to pull you over. They may issue you with three penalty points and a fine or give you a Vehicle Defect Rectification Notice, after which you'll need to prove that you’ve fixed the windscreen fixed 14 days.

Should you cause an accident because your view was obscured by a crack in your windscreen, you could be charged with further motoring offences. Depending on the circumstances, this could result in more points, a driving ban or even jail time.

Will a chipped windscreen cause your car to fail its MOT?

To be considered roadworthy, your car must pass a rigorous MOT check every year (apart from brand new cars, which don’t have to be seen until they turn three).

Your windscreen is divided up into ‘zones’, and it depends on the placement of the chip or crack as to whether it will lead to a failed MOT. There isn’t much tolerance for damage to the glass in Zone A, positioned directly in front of your steering wheel. In fact, any chip 10mm or more here constitutes an immediate fail, because it would block your line of vision. If that’s the case, you won’t be allowed to drive the vehicle again until the crack is repaired.

Chips or cracks in other areas of the glass won’t cause you to fail unless they’re over 40mm in size. However, they'll probably get picked up by your MOT provider and noted on a list of ‘advisory’ fixes that need to be made.

Remember that any damage will leave your windscreen in a weakened state, causing your car structural vulnerability and increasing the likelihood of further problems developing.

How to avoid windscreen cracks

car windscreen repair

There’s no 100% foolproof method to avoiding windscreen chips — because, as we learnt earlier, one of their fundamental jobs is to protect you from flying debris. But not all cracks are inevitable, and here are a few things you can do to prevent them where possible:

  • Drive at an appropriate speed for the road. Country lanes often enforce national speed limits, but on gravel paths, or roads undergoing repair, a much slower speed will stop loose chippings flicking up so high.
  • Keep a safe distance from the vehicle in front. That way there’s less chance of stones flying up from their wheels into your path, or getting hit with rogue debris from unsafe loads.
  • Avoid sudden changes in temperature on your windscreen. For instance, never use boiling water to de-ice it, as this can crack the glass.
  • Keep your windscreen wipers clean. You should also replace them regularly (about once per year) so that they can remove dirt and debris more effectively.
  • Inspect your windscreen regularly for chips. This needn’t be an onerous task, but a quick check every few weeks could prevent small pockets of damage turning into cracks, which present a much bigger problem.


1. How can you fix a windscreen chip?

Windscreen chips are reasonably quick and cheap to fix. All they require is an injection of epoxy resin or acrylic adhesive to seal it off against moisture and strengthen the glass. Do this when you first notice them, and you’ll save the damage from spreading. Always make sure you seek help from a reputable company, as poor repair jobs can cause worse problems further down the line.

Check your insurance policy to see whether windscreen cover is included. It is it, you may just have to pay a small excess to get the job done. And when choosing your insurance next time, consider whether to include this option in your quotes.

Here are our top tips for finding cheap car insurance on price comparison sites.

2. Do I need to replace a cracked windscreen?

Windscreen chips can, very easily, turn into full-blown cracks if they’re not dealt with properly and promptly. You only have to hit a bump in the road — and, let’s face it, we all know lanes riddled with potholes — for the chip to expand.

It may be possible to treat a small windscreen crack in the same manner as a chip. But for larger cracks, you'll probably need to replace the whole windscreen. And yes, that is a lot more expensive than simply filling in a chip.

3. What if I'm driving a work vehicle with a cracked windscreen?

If you’re driving for work, whether in a company car, or your own, it is generally your employer’s responsibility to make sure the vehicle is safe to drive. You have the right to refuse to drive any motor you don’t believe to be roadworthy, and your employer is not allowed to discriminate against you (for instance by disciplining you) should you do so. Make your employer aware of any defects immediately — whether that be a small chip or a large crack — so that they can arrange for it to be repaired before the problem exacerbates.

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