What Is MDAT?

The MDAT is the minimum time required for the adhesive used during installation to cure sufficiently for safe driving.

In most modern vehicles, this period ranges between 30 minutes and 2 hours, depending on the materials and environmental conditions.

Driving before the adhesive has fully set can compromise the bond between the glass and the vehicle, reducing crash protection and potentially affecting airbag performance.

In short:
A windscreen replacement always involves a Minimum Drive-Away Time that must be strictly followed for safety reasons.

A rear window replacement also involves MDAT, and as with a windscreen, the technician’s recommendations should be followed after the replacement.

For side windows that move up and down, there is no adhesive involved in the replacement process.

On three-door hatchbacks, the rear side windows are glued to the frame, and the same applies to small fixed windows such as quarter or vent glass.

However, the MDAT in these cases is not as critical, and the vehicle can typically be used straight away.

What Affects Drive-Away Time?

Several factors influence how quickly the adhesive cures:

• Adhesive Type: Different adhesives cure at different speeds. Modern urethane-based products often set within about an hour, though some may need longer to reach full strength.

• Temperature: Warmer weather speeds up curing, while colder conditions slow it down. The ideal temperature range is typically 15°C to 25°C, where curing is most efficient.

• Humidity: Moderate humidity supports the curing process. Extremely dry or damp conditions can delay bonding and extend MDAT.

• Installation Quality: Proper surface preparation and application technique ensure a consistent and reliable bond.

During the winter months, when temperatures are low, you may find that we request indoor conditions in a preheated environment, or that we invite you to visit one of our workshops across the UK.

This is not to complicate an otherwise hassle-free service, but to ensure your safety when using your car after the job is done.

The bonding process begins as soon as the new glass has been fitted.

Our technicians typically turn on the heat and close the doors while they tidy up after themselves. Similarly, they may warm up the interior before starting the job to soften the old adhesive if your car has been switched off overnight. This makes it easier to remove the damaged windscreen and prepare for installation.

You might also wonder about the tape placed on the edges of your windscreen after it has been replaced — what’s it for?

The tape, known as retention or sealing tape, helps keep the windscreen securely in position, maintains a proper seal, and protects the adhesive while it cures.