Restricted visibility through a car windscreen is a common reason for a vehicle to fail its MOT, around 8% of all MOT failures are for this reason. Worn wipers, dirty windscreens or no washer fluid are reasons for failure but cracks and windscreen chips are also a common cause. Below is an extract from the governments MOT manual that specifies exactly when a windscreen will fail an MOT test in relation to cracks and chips. The manual identifies the area directly in front of the driver as ‘Zone A’ (see diagram below) and the tolerance for damage in this area is lower than for the rest of the windscreen.
Reason for Rejection
“Whilst sitting in the driver’s seat ……. examine the driver’s view of the road through the swept area of the windscreen. In Zone ‘A’: a. damage not contained within a 10mm diameter circle, or ……. c. a combination of minor damage areas which seriously restricts the driver’s view. In the remainder of the swept area: d. damage not contained within a 40mm diameter circle, or e. a windscreen sticker or other obstruction encroaching more than 40mm.”
In English this means if you have a chip or crack directly in front of the driver it will fail it’s MOT if the damage is larger than 1cm. For the rest of the screen damage larger than 4 cm will result in a fail. However be aware that there is some judgement involved in cases where there is more than one point of damage and in these cases you could fail even if the individual chips are less than these sizes.
Why So Small?
A 1cm crack is very small however if it is the driver’s line of vision it can easily obscure their view and cause a distraction leading to late decisions or dangers driving. That is the reason that the government set such a small size limit for their MOT test. This should really make all us drivers sit up and take note. If chips and cracks are so dangerous we should really have a zero tolerance to them and get them fixed straight away to ensure we, and our passengers, are as safe as possible. In addition, if left, the damage often gets bigger making repair harder and in some cases impossible. If you have let your chip or crack get too big your only option will be to replace the entire windscreen which can be expensive.
Windscreen Chip Repairs
Most damage 4cm or smaller can be repaired. The area is cleaned and dried and a clear resin used to fill the gap. You can buy DIY repair kits for under £20 however you need to be confident you can use them correctly as a messy job can result in making visibility worse. There are plenty of windscreen chip repair companies who can do the job for you. Their trained and experienced staff are much more likely to do a quality job and they are usually pretty cheap. In many cases, they can claim the repair cost direct from your insurer. However we would recommend suing a company that don;t also replace windscreens as they don’t have an incentive to up sell you to a larger repair job.
Other Windscreen Tips
- Make sure you always have working window washers and there is plenty of water in your washer tank.
- Make sure your window wipers are in good condition and leave a clean surface.
- Clean grease and dust off the interior of your screen for better visibility.
- Don’t fix stickers in Zone A, make sure they are out of the line of sight of the driver.