1. Windscreen Replacement
Windscreen replacement is the most common service in the automotive glass sector. In Portugal, it is estimated that over 500,000 windscreens are replaced annually, with the majority covered by QIV (Quebra Isolada de Vidros — Isolated Glass Breakage) insurance. The process requires technical expertise, certified materials and strict adherence to curing times to ensure the safety of the driver and passengers.
When is replacement necessary?
Replacement is mandatory when the damage to the windscreen compromises its structural integrity or the driver's visibility. The most common situations include:
- Cracks longer than 15 cm, regardless of location.
- Chips with a diameter greater than 2 cm (approximately the size of a 2-euro coin).
- Damage in the driver's primary field of vision (zone A), where repair is not permitted under Portuguese legislation.
- Multiple chips on the same windscreen that collectively weaken the laminated glass.
- Delamination — visible separation between the glass layers and the PVB (polyvinyl butyral) interlayer.
- Edge damage to the windscreen, within 5 cm of the border, which compromises the bonding.
The Complete Replacement Process
Windscreen replacement follows a rigorous protocol, standardised by European standard BS AU 242 and by adhesive manufacturers' instructions. Each step is essential for the vehicle's safety.
Vehicle Protection and Preparation
The technician protects the instrument panel, A-pillars and surrounding paintwork with dedicated covers. Components attached to the windscreen are removed: interior rear-view mirror, rain and light sensors, ADAS camera (if applicable), exterior trim and any antennas integrated into the glass.
Removal of the Damaged Windscreen
Using a steel wire or a dedicated oscillating blade, the technician cuts through the polyurethane (PU) bead that bonds the glass to the bodywork. This process requires precision to avoid damaging the paintwork or the chassis frame. The old windscreen is removed using professional suction cups.
Bonding Surface Preparation
The old PU bead is trimmed, leaving a uniform layer of approximately 1-2 mm as a base for the new adhesive. The surface is cleaned with a specific primer (usually isocyanate-based) on both the chassis and the new glass. The primer activates the chemical bond between the PU and the substrates.
Polyurethane Adhesive Application
A continuous, uniform bead of PU adhesive is applied around the perimeter of the new glass (or on the chassis frame, depending on the method). Modern adhesives, such as Sika Tack Drive or Dow Betaseal, offer optimised curing times and superior strength. The bead typically has a triangular profile with a height of 10-15 mm.
Positioning and Fixing the New Glass
The new windscreen is positioned using suction cups and precisely aligned with the chassis markings. After seating, the trims, fixing clips and decorative elements are refitted. The vehicle should not be moved during the first few minutes to allow the initial setting of the adhesive.
Curing Time and Safe Drive-Away Time (SDAT)
The Safe Drive-Away Time (SDAT) is the minimum curing period before the vehicle can be driven safely. With current high-performance adhesives, the typical SDAT is approximately 1 hour under normal conditions (temperature between 15-25 °C, relative humidity above 40%). In low temperatures or reduced humidity, the time may increase to 2-4 hours. Full PU curing typically takes 24 to 72 hours.
Component Reinstallation and Calibration
Sensors, ADAS camera, rear-view mirror and antennas are reinstalled. If the vehicle has ADAS systems with a windscreen-mounted camera, system calibration is mandatory. The technician carries out a final inspection and a water leak test.
Materials matter: OEM (original equipment manufacturer) windscreens guarantee perfect fit and all original functionalities. Quality aftermarket glass (brands such as Pilkington, Saint-Gobain Sekurit, AGC or Fuyao) are reliable and type-approved alternatives. All must bear the ECE (E-mark) marking mandatory in the European Union.