Windscreen Replacement: What to Expect
The complete process from booking to driving away. How long it takes, what happens step by step, OEM vs aftermarket glass, and aftercare advice.
Timeline Overview
Same day to 1 week
Booking to fitting
Depends on glass availability for your model
45 to 90 minutes
Fitting time
Old glass removed, frame cleaned, new glass bonded
+1 to 2 hours
ADAS recalibration
If your car has a forward-facing camera
30 to 90 minutes
Safe Drive-Away Time
Minimum wait before moving the car
24 hours
Full adhesive cure
Avoid car washes and rough roads during this period
Total time: Most jobs are completed within half a day. Budget 2 to 3 hours for a standard replacement, or 4 to 5 hours if ADAS calibration is needed.
The Replacement Process Step by Step
Old windscreen removed
The technician cuts the existing adhesive with a specialist wire or knife tool. The old glass is carefully lifted out. This takes about 15 to 20 minutes and is the noisiest part of the process.
Frame cleaned
All old adhesive residue is scraped and cleaned from the frame. The bonding surface needs to be completely clean for the new adhesive to grip properly. A primer is applied to the frame and the new glass.
New adhesive applied
A bead of polyurethane adhesive is applied to the frame (some fitters apply it to the glass edge instead). This adhesive is the structural bond that holds the windscreen in place and contributes to the vehicle's structural rigidity.
New windscreen positioned
The new glass is carefully placed into position and pressed firmly into the adhesive bed. The fitter checks alignment and makes final adjustments. Any sensors, rain detectors, or mirror mounts are reconnected.
Adhesive cure time
The Safe Drive-Away Time (SDAT) begins. During this period (30 to 90 minutes depending on conditions and adhesive type), the bond strengthens enough for the car to be driven safely. The fitter will tell you the exact wait time.
ADAS recalibration
If your car has ADAS cameras, the fitter performs static calibration, dynamic calibration, or both. This can add 1 to 2 hours to the total job time. Some fitters do this on site; others book a follow-up appointment.
Final checks and handover
The fitter checks for leaks, verifies all electronics work (wipers, rain sensor, mirror controls), and cleans up. You receive a work certificate and warranty documentation.
OEM vs Aftermarket Glass
OEM (Original Equipment)
- Made by the same supplier as the factory glass
- Exact match for thickness, tint, and optical properties
- Includes acoustic lamination if originally fitted
- Best fit precision for sensor and camera alignment
- Costs 2 to 3 times more than aftermarket
- Recommended for luxury, acoustic, and warranty-age cars
Aftermarket (OEE)
- Made by third-party manufacturers
- Meets the same BS safety standards as OEM
- May differ in acoustic properties and optical clarity
- Widely available for common models
- 40 to 60% cheaper than OEM
- Fine for standard cars without acoustic glass
The practical advice: For standard hatchbacks and family cars (Ford Fiesta, VW Golf, Vauxhall Corsa, Toyota Yaris), aftermarket glass is perfectly fine and saves significant money. For German luxury cars (BMW, Audi, Mercedes) with acoustic windscreens, or Tesla models with camera-integrated glass, OEM gives a better result and avoids potential issues with noise or ADAS alignment.
After the Replacement
Do not drive until the SDAT period is complete
The fitter will tell you the exact time. Driving too early risks the seal failing.
Avoid car washes for 24 hours
High-pressure water can force its way past uncured adhesive.
Avoid slamming doors for 24 hours
Slamming creates a pressure change inside the car that stresses the uncured adhesive bond.
Leave a window slightly open for the first day
This equalises air pressure and reduces stress on the new adhesive.
Avoid rough roads for 24 hours if possible
Potholes and speed bumps cause vibration that can stress the bond before full cure.
Check for leaks after rain
If you notice water inside the car after rain, contact the fitter immediately. This suggests a bonding fault covered by warranty.
Frequently Asked Questions
Can I drive straight after windscreen replacement?
No. You must wait for the Safe Drive-Away Time (SDAT), typically 30 to 90 minutes. Driving too soon can cause the windscreen to shift or the seal to fail.
What is the difference between OEM and aftermarket?
OEM glass is made by the same supplier as the factory original. Aftermarket (OEE) glass is made by third parties to the same safety standards. For standard cars, aftermarket is fine. For luxury or acoustic cars, OEM is worth the extra cost.
How long is the warranty?
National chains offer a lifetime warranty on workmanship and glass. Independent fitters vary from 1 year to lifetime. Always confirm warranty terms before the job starts.