Flat Roofs – GRP (Fibre Glass)

GRP Roofing 

A properly laid fibreglass roof also known as GRP Roofing, will last for at least 30 years with no measurable deterioration.

All our team have been fully trained by the largest suppliers in the south east.

All our GRP Roofs come supplied with a full 25 year guarantee.

The roof will be laid onto a dry deck in dry conditions at a temperature not below 5°C. The resins and top coats should be suitable for use in GRP Roofing. This guide relates only to the application of the GRP laminate and top coat. Typically two men can strip, re-deck, laminate and top coat a roof of about 20 square metres in one day. We always try to plan starting the roof when a settled period of weather is forecast.


The decking boards will be Sterling OSB3 tongue & groove. They will be fixed to the roof structure using ring shank nails or screws with a minimum penetration of 25mm, which will be used at 300mm centres down the length of each joist covered by the boards. When laying tongue and groove boards, we ensure the gap between the boards is face up so it can be reinforced by the resin that runs into it when the laminate is layed. All the boards must have their joints staggered to increase the strength of the roof.


Edge trims are manufactured in GRP. One side has a high adhesion finish (matt finish), the other side has a glossy finish, always bond to the matt finish. All trims will be fixed with nails or staples to the decking board. With the exception of the F300 Flat flashing and the D260 Angle fillet, the trims will be bonded in place using the Polyurethane Adhesive.Silicone sealant or general-purpose mastics are not suitable adhesives for the fixing of trims. Where trims need to be joined they will be overlapped and bonded with a strip polyurethane adhesive then bandaged together.
The A200 – Drip facia trim can be offset in order to ensure that the drip stands over the gutter. Preformed corners may be used, or if preferred, mitres can be cut into the trim to form the corner then sealed on site with a patch of glass fibre.
The laminating will be planned depending on the air temperature.

Long runs may be attempted in cooler conditions while short runs must be used in hotter conditions. Remember that the resin will always cure faster in hotter conditions and an allowance will be made for this when deciding how much glass to lay in one mix. (The Glass : Resin ratio should be 1:2.5). Before the laminate is applied the glass will be pre-cut to the desired length., shorter lengths in hotter conditions.  Do not step on the wet glass and resin. We will continue this until the roof has been completely covered and the laminate has been well consolidated.

Top coat 

The laminated roof will be top coated as soon as possible –  The laminate is about half cured when it is impossible to move the glass fibres within the resin matrix. 

The GRP Roof is then complete and will take several days to fully cure. It will not deteriorate and maybe cleaned occasionally with soap and warm water. DO NOT USE BLEACH or any strong alkali on the roof. 

The roof will withstand foot traffic and may have planters or tiles or other decorative finishes applied to it with no detrimental effects. The edge trims may be painted if required. 

The top coat comes in a variety of colours, but mostly used is light grey, mid grey and dark but other colours are available on request.

Contact us by using our email form or ring 07837 230576