How many of us haven't winced at the sound of a stone or other object hitting our windscreens? After all, a big piece of glass right in front of one's face is definitely not something to be ignored, especially when stuff is bouncing off it. However, there is sometimes more to worry about than just the sound.
At certain times, our windscreens are particularly vulnerable to damage. During autumn and winter, sudden changes in temperature, extra debris on the roads after storms and unwise methods of de-icing frozen windscreens are all likely to end up damaging that big piece of glass.
Similarly, when your local authority has finally got around to that bit of road resurfacing you've been complaining about, the fresh layer of loose stone chips seems almost magically attracted to your windscreen.
Visibility and the MOT
The condition of windscreens comes under the heading 'Visibility' in the MOT test. For test purposes, windscreens are divided into zones.
The most important zone, Zone A, is described by the government's MOT Inspection Manual as being;
- in the swept area of the windscreen
- 290mm wide
- centred on the steering wheel
Is minor damage a problem?
We should point out that even small chips and cracks can become very big ones in an instant. Your humble blogger has personally had a slightly chipped windscreen suddenly crack from top to bottom after driving over a speed bump. It's best to fix the small things before they become alarmingly big things.
Where the MOT test is concerned, the principle set out in the government guidance is that damage should only cause test failure if the driver's view of the road is significantly impaired:
You should only fail the windscreen if the view is significantly affected. If only the driver’s view of the sky or the bonnet is affected, it should not be rejected.
[...]
Failure for damage is only justified if the damage significantly affects the driver’s view of the road. You do not need to consider the effects on tall or short drivers.
In practice, it is best to assume that a chip or crack measuring more than 10mm within Zone A will result in a test failure unless it is properly repaired, and that an unrepaired chip or crack measuring more than 40mm within Zone B will also cause MOT failure.
Repair or replace?
The MOT test guidance says:
Repaired windscreens must be judged solely on whether the repair interferes with vision. An ‘invisible’ or barely detectable repair, finished flush with the surrounding glass, does not count as damage.
A windscreen repair kit, or a professional repair may fix damage to the extent that the windscreen will pass the MOT test. Professional repairs are usually best because repair companies have superior equipment and more experience than the average car owner. That experience enables them to assess whether a repair has done a good enough job or not. Some DIY repairs do not pass the MOT test.
Professional repair companies, especially those approved by insurers, should carry out repairs to British Standard BS AU 242b, which was issued in 2022. This means that windscreen companies aren't just guided by the MOT requirements, but also a very specific set of requirements set out in the standard.
BS AU 242b defines windscreen zones differently to the MOT guidance. It also takes into account technology that might be affected by damage or repairs to the windscreen, or by replacing the windscreen, such as Advanced Driver Assistance Systems (ADAS) and Heads Up Displays (HUD).
Your (or your insurer's) chosen windscreen specialist will assess any damage to the windscreen and advise whether replacement or repair is required.
Be sure to tell the windscreen company if your vehicle has rain sensor-equipped windscreen wipers, if the windscreen is heated, or if there is any other technology that might be affected.
Insurance implications
Check your insurance policy before contacting a windscreen company. Many insurance policies include windscreen replacement, provided you use a company approved by the insurer, and sometimes there is no excess to pay (or only a small excess).
Claiming for a windscreen repair or replacement shouldn’t affect your no-claims discount in most cases. So, check your policy and then contact your insurer.
Don't forget the wipers
Missing, faulty or ineffective windscreen wipers can also cause your car to fail its MOT test or get you into hot water with the police, so check their condition and effectiveness regularly. New wiper blades are cheap, easy to fit (they come with instructions) and very widely available - probably even from your local supermarket.
The same is true of your screen washers. If they don't work, or if they don't provide adequate water or solution to clean the windscreen properly, you risk an MOT failure and/or penalty points on your licence.
According to RAC, driving with faulty or missing wipers could earn you a £2,500 fine and three penalty points. If you commit the offence twice within three years of the original offence, you may be disqualified from driving for a minimum of six months.
If you are caught without cleaning fluid in your washer reservoir, you may get a £100 fixed penalty and three points on your licence.
