Cracked Windscreen: MOT Failure?

The MOT test is a crucial annual inspection designed to ensure your vehicle meets roadworthiness and environmental standards. While many components are routinely checked, one area that often sparks concern is the condition of the windscreen. A seemingly minor crack or chip can, under certain circumstances, be the reason your car fails its MOT. Understanding the specific criteria used by examiners is key to avoiding an unexpected failure and ensuring your vehicle remains legal and safe to drive.

Understanding the MOT Windscreen Regulations

The Driver and Vehicle Standards Agency (DVSA), which oversees MOT testing in the UK, has clear guidelines regarding windscreen damage. The primary concern is visibility. If a crack or chip obstructs the driver's view of the road, it's a potential failure point. This isn't just about aesthetics; it's a fundamental safety issue. Impaired vision can lead to accidents, making it imperative that windscreens are kept in good condition. The regulations specify the size, position, and type of damage that will result in a fail.

Where the Damage Matters: The "Toughened Glass" Zone

The MOT test focuses on specific areas of the windscreen. The critical zone is the area swept by the windscreen wipers. If there is damage within the driver's primary field of vision, it's highly likely to cause a failure. The DVSA defines this area as:

• Directly in front of the driver.
• An area in the driver's line of sight.

More precisely, the regulations refer to a "zone A". This zone covers the area swept by the passenger side wiper. If any damage within this zone is larger than 10mm, it will result in a failure. For any damage outside this primary swept area, but still in the driver's field of vision, a larger chip or crack is permissible, up to 40mm in diameter. However, even these larger chips must not be within the smaller 10mm area.

Types of Windscreen Damage and Their MOT Implications

The nature of the damage also plays a significant role. The MOT test differentiates between chips and cracks:

• Chips: These are typically small, circular or star-shaped damage points. A chip less than 10mm in diameter in the driver's primary field of vision is usually acceptable. However, if a chip is larger than 10mm but less than 40mm, it will fail if it's within the swept area of the driver's side wiper.
• Cracks: Cracks are more serious as they can spread and further compromise the windscreen's structural integrity. A crack that extends across the windscreen, or a crack that is branching from a chip, is likely to cause a failure. If a crack is longer than 10mm and within the driver's primary field of vision, it will fail. Multiple cracks or a combination of chips and cracks can also lead to a fail, even if individual pieces of damage seem minor.

The "Swept Area" Explained

The "swept area" is a crucial term in MOT regulations. It refers to the portion of the windscreen that is cleared by the windscreen wipers. The DVSA specifically states that damage within the area swept by the driver's side wiper is more likely to cause a fail. This is because the wipers are essential for maintaining visibility in adverse weather conditions. If damage is located in a spot that the wipers regularly pass over, it can create further smearing or obstruction, especially when water or dirt is present.

Table: Windscreen Damage and MOT Pass/Fail Criteria

To simplify, here's a breakdown of common windscreen damage scenarios and their likely MOT outcomes:

What Constitutes the "Driver's Field of Vision"?

The driver's field of vision is the area of the windscreen that the driver needs to see through to safely operate the vehicle. This is generally considered to be the area directly in front of the driver, extending to the sides as far as is necessary to perceive hazards. The MOT test specifically focuses on any damage that could impair this crucial view. If a crack or chip is positioned such that it requires the driver to move their head or eyes unnaturally to see past it, it's likely to be considered a failure.

Can a Small Chip Cause a Fail?

As highlighted in the table, a very small chip, less than 10mm in diameter, located within the driver's primary field of vision and within the swept area, should technically pass. However, it's always advisable to get even minor chips repaired. Small chips can easily spread into larger cracks, especially with temperature changes or vibrations, and then become a definite MOT failure. Furthermore, some examiners might be more stringent, and a chip that is borderline could still lead to a fail if they deem it to be a significant obstruction.

The Importance of Windscreen Repair

Proactive windscreen repair is far more cost-effective than replacement and can prevent MOT failures. Most reputable garages and specialist windscreen repair services can fix minor chips and small cracks. Repairing a chip not only restores the windscreen's structural integrity but also prevents the damage from spreading, saving you money and hassle in the long run. It's a small investment to ensure your vehicle remains roadworthy and safe.

What to Do if Your Windscreen is Damaged

If you notice a chip or crack in your windscreen, don't delay in getting it assessed. Many insurance policies include £0 excess windscreen cover, meaning you can get it repaired or replaced for free. Even if you have to pay out of pocket, the cost of a repair is significantly less than a full windscreen replacement, and certainly less than the cost of a failed MOT and subsequent re-test. Take your car to a professional who can advise on the best course of action.

Frequently Asked Questions

Q1: Can a crack on the passenger side of the windscreen fail my MOT?

A: It depends on the size and exact location. If the crack is within the driver's primary field of vision or the swept area of the driver's side wiper and exceeds the specified dimensions (10mm for chips in the swept area, 40mm for chips outside but still visible, or any crack over 10mm in the driver's view), it can cause a fail. Damage purely on the far passenger side, completely outside the driver's view and the wiper sweep, is less likely to cause a fail unless it compromises the overall structural integrity of the glass.

Q2: My windscreen has a small chip, but it's not directly in front of me. Will it pass?

A: If the chip is less than 40mm in diameter and is not within the area swept by the driver's side wiper, it should generally pass. However, if it's anywhere in the driver's direct line of sight, even if outside the swept area, it could still be an issue if it's over 10mm. It's always best to get it checked by a professional.

Q3: What if the damage is on the outside of the windscreen only?

A: The MOT test assesses the damage to the glass itself, not whether it's on the surface or penetrated. If the damage is visible and obstructs the driver's view according to the defined criteria, it can still lead to a failure, regardless of whether it's a surface scratch or a deeper chip.

Q4: How often should I check my windscreen?

A: It's good practice to visually inspect your windscreen regularly, perhaps once a month, and certainly before your MOT is due. Look for any new chips or cracks, especially after driving in poor weather or on rough roads.

Q5: Can I drive with a cracked windscreen if it's not my MOT date yet?

A: While a cracked windscreen might not cause an immediate fine if it doesn't impair your vision significantly, it is illegal to drive a vehicle with a windscreen that is so damaged that it is likely to impair the driver's vision. It's always recommended to get it repaired or replaced as soon as possible to ensure safety and avoid potential penalties.

Conclusion

In summary, a cracked or chipped windscreen can indeed cause a car to fail its MOT. The key factors are the size, position, and type of damage, with particular attention paid to the driver's field of vision and the area swept by the wipers. Regular inspection and prompt repair of any damage are the best ways to ensure your vehicle remains roadworthy and passes its annual MOT test with flying colours. Don't let a seemingly minor windscreen issue compromise your safety or lead to an unnecessary failure; get it checked and repaired by a professional today.

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