Fibreglass Matting — 300g, 450g & 600g Chopped Strand Mat

Why Matting Weight Matters

Chopped strand mat is the structural core of a GRP laminate. The weight per square metre directly determines the thickness and strength of the cured roof. A 300g laminate is physically thinner and lighter than a 450g laminate — it suits small light-use roofs but is not strong enough for a garage or extension where thermal movement, foot traffic during maintenance and long-term performance demand a 450g or heavier laminate. Using 300g mat on a garage roof because it is cheaper is a false economy that typically results in cracking and early failure.

Woven Tape For Joints and Perimeters

In addition to chopped strand mat for the main roof surface, woven fibreglass reinforcement tape is used at specific positions — board joints, trim junctions, internal corners and the base of upstands. Tape provides concentrated reinforcement at movement-prone details where the main mat alone does not give enough support. It is applied before the main mat layer and saturated with the same roofing resin.