Terms and phrases used in the GRP Roofing industry



Acetone is a cleaning solvent that is used to GRP roofing resins from rollers and brushes so that they can be re-used.

Bubble Buster

Also known as consolidating rollers and paddle rollers, these are made for the GRP roofing market that reduce splash back when used with the base resin system.


Catalyst sometimes called activator or hardener is the chemical that is mixed into the GRP roofing resins and topcoats to start the curing process.

Catalyst Dispenser

A specially designed method for safely measuring and dispensing catalyst.


CSM stands for chopped strand matting and is the fibreglass that is used with the base resin to reinforce the system giving it strength.



Consolidating and laminating is the process of bonding the glass fibre to the OSB decking by applying the matting to the decking and rolling it with a paddle roller. This breaks down the binder of the fibreglass and gets any air out of the surface.


The laminate refers to the surface created when the GRP roofing resin bonds to the chopped strand matting and is fully cured.

Green Trimming

Green trimming is the process of tidying up the glass fibre around the trims and corner section usually with a retractable knife when the main laminate is cured but not solid.

Pot Life

The amount of working time you have with the catalysed GRP roofing resins and topcoats before it starts to cure.

Wetting Out

To reach full strength the chopped strand matting in the GRP roof should be fully saturated with the resin system. When the glass fibre reaches this stage it's called wetting out.

Technical Terms


Chopped strand matting is made up of tiny strands of glass bonded by an emulsion binder which breaks down when the polyester GRP roofing resin is applied.


A term used to describe what happens when the main GRP roofing membrane comes away from the decking underneath.


An exothermic reaction is a chemical reaction that releases energy heat. The GRP roofing base resin when activated with the catalyst will generate heat by the polymerisation process and will become noticeably hotter.