Can I drive with a cracked windscreen?

A crack can differ in position, extent and condition. It may affect the driver's view, reach an edge, change over time or sit within glass whose overall condition also needs attention.

Those factors have to be considered together and in the context of the vehicle and windscreen. A measurement on its own cannot determine whether an individual vehicle is appropriate to continue driving.

The current DVSA MOT inspection manual sets specific criteria for windscreen damage. Within Zone A, damage over 10mm is considered; in the remainder of the windscreen's swept area, the corresponding figure is over 40mm.

The manual also states that failure for damage is justified where it significantly affects the driver's view of the road. These figures are MOT inspection criteria. They are not universal legal limits or automatic permission to continue driving.

DVSA defines Zone A as an area within the swept area of the windscreen. It is 290mm wide and centred on the steering wheel.

The Zone A criterion reflects the importance of the driver's forward view during an MOT inspection. It still does not turn the 10mm figure into a general roadworthiness rule for every crack or every vehicle.

GOV.UK states that the driver is responsible for making sure a vehicle is safe to drive, or roadworthy, and that a vehicle can be unsafe even when it has a current MOT certificate.

An MOT records the vehicle's condition when it was tested. It does not remove the need to consider damage that develops or changes afterwards. This guide provides general information and cannot determine the roadworthiness of an individual vehicle without an assessment.

Clear visibility is a practical part of judging damaged glass. The Highway Code states that windscreens and windows must be kept clean and free from obstructions to vision.

A crack should therefore be considered in relation to what the driver can see and the condition of the glass. That does not mean every visible crack automatically makes a vehicle unroadworthy.

Official GOV.UK guidance states that, for this assessment, a crack passing through the swept area of the windscreen and reaching two points at the edge is deemed to render the windscreen insecure.

That is a specific description. It should not be shortened into a claim that any crack touching any edge automatically determines the legal or roadworthy status of a vehicle.

A crack may change or spread as the glass experiences vibration, temperature changes or further stress. How it develops depends on the damage and the condition of the windscreen.

It is not accurate to claim that every crack will definitely spread. An assessment deals with the windscreen's current condition rather than relying on a guaranteed prediction.

Once damage has developed into a crack, whether any repair is appropriate depends on the actual damage and should be professionally assessed.

For detailed guidance on earlier-stage stone-chip damage, see the related guide below.

Some vehicles have driver-assistance cameras mounted at or viewed through the windscreen. If replacement is required, the vehicle and applicable procedure may make ADAS assessment or calibration relevant.

That requirement is vehicle-specific. A cracked windscreen does not by itself establish that calibration is automatically required.

Horizon assesses the actual damage, its location, the condition and specification of the windscreen, and relevant ADAS considerations where applicable.

That assessment provides the basis for advising on the appropriate next step for the vehicle.