The Crucial MOT Windscreen Chip Rule Explained
When your vehicle undergoes its annual MOT test, the condition of your windscreen is scrutinised, and a chip or crack could lead to failure. The primary concern for the MOT tester is whether the damage obstructs the driver's view or compromises the structural integrity of the glass. Specifically, the DVSA (Driver and Vehicle Standards Agency) rules state that if a chip or crack is within the area swept by the windscreen wipers and is larger than 10mm, it will result in a fail. Similarly, any damage within the 'A' zone (the area directly in front of the driver, extending to the centre of the dashboard) that is larger than 40mm can also cause an MOT failure.
- Chips in the driver's direct line of sight usually fail MOT.
- Damage larger than 10mm within wiper sweep area fails.
- Cracks over 40mm in the driver's 'A' zone fail.
- Structural integrity and visibility are the key MOT concerns.
It's not just about the size; the location is paramount. A small chip, perhaps on the passenger side or near the roofline, might not be an issue. However, if that same chip, or a collection of smaller chips, begins to spread or creates a significant distortion, it could then present a hazard. The MOT test isn't designed to catch every minor imperfection, but rather to ensure your vehicle meets minimum safety standards. A damaged windscreen can impair visibility, especially in adverse weather conditions, and could even shatter more easily in an accident.
Drivers often worry about any mark on their windscreen, but the regulations are quite specific. Understanding these measurements and zones is key to knowing whether your windscreen issue needs immediate attention before presenting your car for its MOT.
Inspect your windscreen thoroughly before your MOT appointment, paying close attention to the dimensions and areas specified by the DVSA.
The MOT tester's job is to assess the vehicle against a defined set of standards. They will use specific tools and visual checks to determine if your windscreen complies. If a chip is borderline, they will measure it against the regulations. It is essential to remember that the tester's decision is based on these objective criteria, aimed at maintaining road safety for everyone.
Identifying Windscreen Damage for MOT Purposes
What exactly constitutes a failure-inducing windscreen chip or crack during an MOT? The DVSA provides clear guidelines, and understanding these can save you time and money. The crucial area is the 'swept area' of the windscreen – the part cleared by the windscreen wipers. Within this zone, a single chip or multiple chips that collectively form a crack measuring over 10mm will cause the vehicle to fail its MOT. This measurement refers to the longest dimension of the damage.
Beyond the swept area, the MOT test also considers the driver's direct field of vision. This is often referred to as the 'A' zone, which spans the area directly in front of the driver. If there is any damage (chip or crack) within this zone that is larger than 40mm, it will also lead to an MOT failure. This damage could be a single crack or a pattern of cracks that, when measured across their widest point, exceed this limit. The intention is to ensure the driver's view of the road is unobstructed and clear.
What About Cracks vs. Chips?
While the term 'chip' is commonly used, the MOT regulations apply to all types of windscreen damage. A stone flicked up from another vehicle can cause a small chip, often described as a 'bullseye' or 'star' fracture. If this chip then spreads into a long crack, it is still subject to the same rules. A crack that extends across the windscreen, especially if it enters the driver's 'A' zone or is extensive within the swept area, is very likely to result in a fail. The MOT tester looks at the overall impact on visibility and structural integrity, regardless of whether the original damage was a chip or the start of a crack.
The tester will not just look at the surface; they will assess the depth and spread of the damage. For instance, a shallow chip that hasn't penetrated the glass might be deemed less critical than a deeper one that has weakened the windscreen's structure. However, the primary criteria remain size and location relative to the driver's view and the wiper sweep.
It is worth noting that some minor imperfections that do not affect the driver's vision or the windscreen's structural integrity may pass. However, relying on this is risky. If in doubt, it is always best to seek professional advice.
What Happens If My Windscreen Chip Fails the MOT?
If your vehicle fails its MOT specifically because of a windscreen chip or crack, it doesn't mean you need a whole new windscreen in every instance. The immediate consequence is that your vehicle is not legally roadworthy until the issue is rectified and it passes a partial retest. This retest typically focuses only on the item that caused the failure.
The first step after a failed MOT due to a windscreen chip is to get the damage assessed by a professional windscreen repair specialist. Many reputable companies offer services such as budjet tyres & mot, ealing tyres servicing & mot, or local garages that specialise in windscreen repairs. They can determine if the chip or crack is repairable. Modern windscreen repair techniques can often fix chips and small cracks effectively, restoring the glass's structural integrity and improving clarity. This is usually a much more cost-effective solution than a full replacement.
When is a Windscreen Replacement Necessary?
A windscreen replacement becomes necessary when the damage is too extensive to repair, or if the repair would not restore the windscreen to a safe, compliant standard. As mentioned, if the chip or crack is within the driver's line of sight (the 'A' zone) and exceeds 40mm, or if damage within the swept area is over 10mm, it will fail. If a repair cannot bring the damage within these limits, or if the damage is too close to the edge of the screen, a replacement is the only option.
A proactive approach to windscreen damage can prevent costly MOT failures and ensure your continued safety on the road.
Once repaired or replaced, your vehicle will need a partial retest. Many garages that conduct MOTs also offer this service. You will need to present your vehicle again for the retest, which will specifically check the windscreen. If it now meets the required standard, your vehicle will pass the MOT. If the repair or replacement hasn't resolved the issue, you may need to seek further advice or have the work redone before another retest.
The costs associated with a failed MOT can add up, including the cost of the initial MOT, the repair or replacement, and the partial retest fee. Therefore, addressing windscreen damage promptly is always advisable.
Preventative Checks and Keeping Your Windscreen Safe
While the MOT test is an annual event, maintaining your car's windscreen should be an ongoing practice. The most common cause of windscreen chips and cracks is impact from road debris, such as stones or grit. These can be flicked up by other vehicles, particularly at higher speeds or on roads undergoing maintenance. While you can't always avoid these incidents, being aware and taking certain precautions can help minimise the risk.
One proactive measure is to maintain a safe following distance from other vehicles, especially lorries or commercial vehicles that might be carrying loose materials. Driving on roads with good surfaces also reduces the likelihood of encountering debris. If you notice a small chip on your windscreen, even if it's not in an area that would cause an immediate MOT failure, it's wise to consider getting it repaired sooner rather than later. Small chips can spread rapidly, especially when exposed to temperature changes (from heating or air conditioning), vibrations from driving, or the stress of hitting a pothole. A timely repair can prevent a minor issue from becoming a major one that leads to an MOT failure or necessitates a full replacement.
What to Look For in a Windscreen Repair
When seeking a repair, look for specialists who use approved methods and materials. The repair process typically involves injecting a clear resin into the damaged area. This resin is then cured, often using UV light, to bond the glass back together. A good repair should restore the windscreen's strength and minimise the visibility of the chip. It's important to understand that a repair may still leave a slight blemish, but it should no longer be a structural weakness or obstruct the driver's view.
Remember that MOT rules can be updated, so it is always prudent to check the latest dvsa new mot rules or consult with your local MOT testing station if you have any specific concerns about your vehicle's windscreen condition. Staying informed about mot tyre rules and other vehicle safety aspects also contributes to overall roadworthiness.
By being vigilant about the condition of your windscreen and addressing any damage promptly, you not only increase your chances of passing your MOT test but also contribute to your own safety and the safety of other road users.