The windscreen of your car plays a crucial role when it comes to driving safely, such that if you are driving with a damaged windscreen, even if that damage is only minuscule, you need to be aware of the potential risks involved, both practically and legally speaking.
In this guide for motorists, we explain why having a damage-free windscreen when driving is so important for safety reasons. We also look at the rules relating to windscreens from a legal point of view, including “Is it illegal to drive with a cracked windscreen on UK roads” and “Can you drive with a chip on the windscreen?”.
Why is it so important to have a damage-free windscreen?
Being able to clearly see the road ahead is essential to safe driving where, in turn, having a clear and undamaged windscreen is vital for good vision. As such, the windscreen of your vehicle needs to be kept in good condition otherwise, depending on the location of any damage, even a small chip or crack can impede your vision making it difficult to see approaching traffic and other road hazards. In this way, you would pose a danger not only to yourself, but to other road users. Any small chips and cracks, even on the passenger side could also exacerbate the dazzle and glare from sunlight or headlights of oncoming cars.
In addition to compromising visibility, even minor damage can effect the structural integrity of your vehicle’s windscreen. This can make the glass more susceptible to either shattering when hit by flying road debris, or suddenly cracking with road vibrations or any changes in temperature, again putting the lives of you, the occupants of your car and other road users at risk. It is a common myth that because all modern windscreens use safety glass, this cannot shatter. This is simply not the case. Although safety glass comprises two layers of glass with a thin plastic film between the layers, where this lamination is designed to hold the glass together, a shattered windscreen can still significantly obstruct the driver’s view.
Chipped windscreens & passenger safety
The windscreen of your vehicle is not just a barrier to protect you against the elements. It is an essential structural component, where any damage can weaken it. The windscreen may not seem like your vehicle’s most obvious safety feature, but a well-fitted and well-maintained windscreen plays more of a role in keeping you and your passengers safe than you might initially think. This is because, if an accident should happen, a structurally sound and correctly installed windscreen can help to prevent passenger ejection, prevent a roof-collapse in an accident where the car rolls over, and allow airbags to properly inflate.
When it comes to the risk of passenger ejection in a road traffic accident, it goes without saying that you and any passengers should be wearing a seatbelt at all times when the vehicle is moving. However, in the event of a collision, the windscreen will also serve as a barrier to prevent the driver and anyone else from being ejected. If the glass has even a small chip or crack in it, this means it is fundamentally weaker than it ought to be and may not be able to withstand the force of a person being hurled against it at great speed.
Equally, in the context of rollover accidents, as modern cars get lighter and their pillars get slimmer, greater reliance has been placed on windscreens to provide occupant protection. With a windscreen providing over half of the strength to prevent the car roof from caving in, if already damaged in some way, it is possible that the windscreen would simply shatter.
Finally, front airbags rely on the rigidity of the windscreen to be able to inflate outwards and provide the maximum amount of protection. If a windscreen is damaged, the force exerted as the airbag deploys can shatter or detach the windscreen, causing the airbags to inflate in the wrong direction, leaving the driver and front passenger without protection.
Are you driving a ‘roadworthy’ vehicle?
By law, your vehicle must be legal and roadworthy, where driving an unroadworthy motor vehicle may also invalidate your insurance. As such, cars must normally pass an MOT test three years from the date of their first registration and every year after that.
Specifically, under section 30(3) of the Road Vehicles (Construction and Use) Regulations 1986, all glass 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. The Highway Code also states that windscreens must be kept clean and free from any obstructions to vision.
Finally, under section 40A of the Road Traffic Act 1988, a person will be guilty of an offence if they use a motor vehicle on a road when the condition of that vehicle is such that its use involves a danger of injury to any person, including the driver themself, any passengers or other road users. As such, it is an offence to use a vehicle in a dangerous condition, including where damage to the windscreen presents a serious road safety risk.
Is it illegal to drive with a cracked windscreen?
In many cases, where a windscreen is cracked, this will mean that the vehicle is not roadworthy and therefore illegal to drive, where it is an offence to drive a vehicle in a dangerous condition. This is because a crack to the windscreen is more than likely going to obscure the driver’s view, or be at risk of doing so if the crack spreads while driving.
This essentially means that even if the crack is not directly obscuring your view as a driver, this still poses a risk of danger if the glass shatters or cracks even further. As cracked glass is also likely to dramatically impact the structural integrity of the windscreen, this will increase the risk of injury if an accident occurred, for example, by undermining the airbags.
Can you drive with a chip on the windscreen?
Unlike a cracked windscreen, there is far less likelihood that a chip on the windscreen will present the same level of risk when it comes to road safety. However, if the chip is directly in the driver’s line of vision, where they do not have a clear view of the road ahead, this could still potentially make the car unroadworthy and illegal. As such, if you have a chipped windscreen, it is always best to get this repaired as soon as possible.
In those cases where a chipped windscreen is impeding your view and you are involved in a collision, it is likely that your car will come under close scrutiny by the police. You may find yourself being prosecuted for an offence, even if the accident was not your fault. You may even be held liable for the accident because of the condition of your vehicle, as any obstruction to your view of the road can make it more likely that you were to blame.
Penalties for driving with a defective windscreen
If you are found guilty of a motoring offence or, alternatively, you accept a fixed penalty or plead guilty to an offence, your driving licence will be endorsed with a certain code. You will also be given penalty points on a scale from 1 to 11, with more points for more serious offences. This includes what are described as ‘construction or use’ offences.
Under this category of motoring offence, for causing or likely to cause danger by reason of use of an unsuitable vehicle or using a vehicle with parts or accessories in a dangerous condition, with the endorsement code CU20, you will receive 3 penalty points and a fine.
However, if you drive with a cracked windscreen and are subsequently involved in a road traffic accident, you could be charged with a far more serious driving offence.
MOT windscreen rules
If you take your car in for its MOT and there is damage to the windscreen, a pass or fail will depend on the location and size of any chip or crack. In most cases, if there is damage of 40mm or more anywhere on the windscreen, your vehicle will fail. This means that, before being retested, the chip or crack will first need to be fixed. Ideally, however, this should be repaired before going in for its MOT to avoid any delays and duplicate charges for a retest.
Importantly, even a 10mm-sized chip or crack on your windscreen could result in an MOT fail if the damage falls within what is known as Zone A of your vehicle’s windscreen. This zone refers to the 290mm-wide section of the windscreen that is centred in front of the steeling wheel, in other words, directly in the driver’s line of vision.
The general rule is, if damage hinders the vision of the driver, it is illegal for the car to be on the road and will fail its MOT. Most small chips will not be an instant MOT failure, but they should still be repaired as soon as possible as they can develop into severe cracks.
What should you do if you notice a chip on your windscreen?
Even though issues with your windscreen might seem less pressing than a mechanical fault, windscreen damage can be extremely hazardous, not only to you and the occupants of your car, but to other road users. While a small chip may not initially affect your vision, it is likely to expand and increase in size over time. If this eventually or suddenly forms a crack, this will usually require a replacement windscreen at significantly higher cost.
Anything from the pressure of driving at high speeds, or the slight contraction and expansion of glass in different temperatures, can cause a chip to become a full-blown crack. Further, even though the majority of road debris that hits your windscreen is small in size, it is sometimes enough to shatter the whole windscreen, especially if it hits a weak spot.
Fortunately, depending on the size and position of a chip to the windscreen, this is typically easy to fix by injecting a resin into it and smoothing it over. This will seal the chip, preventing any moisture and dirt getting into it, and whilst a blemish may still be visible, it will restore the structural integrity of the windscreen and the car will be safe to drive again.
How can you prevent getting a chipped windscreen?
Chipped or cracked windscreens most commonly occur after being hit by loose stones, gravel, grit or other debris thrown up from the road by the tyres of other cars. While it would be virtually impossible to prevent this, you can reduce the risk of this happening by:
- driving at a sensible distance from the vehicle in front whose tyres may kick back debris, leaving plenty of space between your car and the one ahead
- driving carefully on any road with poor surfaces, including any highway under repair, to avoid stones, gravel and grit from hitting the windscreen of your vehicle
- driving at a sensible speed to minimise the risk of flying stones, gravel and grit
avoiding pouring hot or boiling water on to the glass to defrost the windscreen in colder temperatures, where a sudden increase in temperature can easily crack the glass
- replacing your windscreen wipers regularly, at least once a year, to ensure that they are efficiently removing built-up dirt which can help to prevent chips and cracks
- regularly inspecting your windscreen for any signs of slight damage, and arrange for the immediate repair of small chips or cracks to prevent these from spreading.
If your windscreen does need replacing, it is vital that this is done by an expert technician using good quality safety glass, as a poorly fitted windscreen and/or substandard glass can, of itself, compromise the structural integrity of the windscreen and its ability to protect you.
Driving with a chipped windscreen FAQs
Is it illegal to drive with a cracked windscreen in UK?
If a cracked windscreen obstructs your view of the road ahead, you could be prosecuted by the police for causing or likely to cause danger by reason of use of a vehicle with parts or accessories in a dangerous condition.
What is the legal limit for a cracked windscreen?
A vehicle will fail its MOT if there is any windscreen damage of at least 10mm in size directly in the driver’s line of vision. In these circumstances, the windscreen would need to be repaired or replaced before being retested.
What to do if you have a cracked windscreen?
If you have a cracked windscreen, you should get this repaired immediately. The damage will not repair itself and this is only likely to get worse which, in turn, could significantly obstruct your view and cause a road traffic accident.
Will a cracked windscreen shatter?
A cracked windscreen can easily shatter, although modern screens comprise two layers of glass with a thin plastic film between the layers designed to hold the glass together. Still, a shattered windscreen can significantly obstruct the driver’s view.
The matters contained in this article are intended to be for general information purposes only. This article does not constitute legal advice, nor is it a complete or authoritative statement of the law, and should not be treated as such. Whilst every effort is made to ensure that the information is correct, no warranty, express or implied, is given as to its accuracy and no liability is accepted for any error or omission. Before acting on any of the information contained herein, expert legal advice should be sought.