The GRP System (Fiber Glass System) (Supply & Fit or Supply Only)

This Unique System Can Be Supplied in Sheet Form for Dry Lay Situations or in the Traditional Laminating Procedure.

Guaranteed for 20 years (Insurance Backed Upon Request)

The GRP (Glass Reinforced Polyester) or Fibreglass system has been in the market place for decades, and is widely used in industrial and domestic instances, The reason being is that there is no requirement for the boiling pot or torches as with the roll and pour and torch on systems, the whole system is a no heat application that means no naked flame.

Fibreglass Flat Roofing

A properly laid fibreglass roof also known as GRP Roofing, will last for at least 30 years with no measurable deterioration. The roof must 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. The deck should be of 18 mm OSB3 T&G laid wrong side up with staggered joints and be well fixed to the underlying joists. Typically two men can strip, re-deck, laminate and top coat a roof of about 18 square metres in one day. Always try to plan starting the roof when a settled period of weather is forecast. You should ensure that the new deck is laid to adequate falls (1:60 or 1:80) in order to allow drainage.


All the board joints and all the trims must be "bandaged "to the roof to ensure that no stress cracking can occur at the joints. This is done by applying a 3" wide glass bandage to each joint and to all the trim edges. These bandages must be well consolidated. 

The procedure for bandaging is the same, on a smaller scale as that used for the main laminate. A small amount of resin, usually about 1 kilo is decanted into a small bucket and mixed with catalyst. (A chart for a guide to the correct amount of catalyst is available). The resin is the applied to the board edges and to the trim edges with either a 3" brush or small roller. The pre-cut bandage is then rolled out over the resin and a further amount of resin is then applied to the glass bandage, which is allowed to wet out before consolidating with a small consolidation roller. All the detail work may also be completed at this stage, drain outfalls, channels, pipes and roof fittings can all be sealed with GRP You will find that a brush is more useful to form complex shapes and to consolidate the glass than a roller for these details.


The main laminate may be applied before or after the bandage has cured. The laminating must 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 must 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 must be pre-cut to the desired length., shorter lengths in hotter conditions. The laminate need not be laid to falls, i.e. it does not matter in which direction the joints are lapped. Clear all unnecessary items off the roof and mix sufficient resin and catalyst to complete the first "run". Wet out the first area to be done and roll out the glass. Apply the remainder of the resin to the glass, allow to wet out for a few minutes, then consolidate the glass with the consolidation roller ensuring that no dry patches of glass remain and that no air is trapped in the laminate. 

Continue with the next "run" of glass overlapping the first by 50mm. Do not step on the wet glass and resin. Continue this until the roof has been completely covered and the laminate has been well consolidated.

Top Coating

The laminated roof must be top coated as soon as possible - Try not to leave the laminate overnight. Test the laminate for cure by using slight finger pressure. The laminate is about half cured when it is impossible to move the glass fibres within the resin matrix. At this point it will withstand light foot traffic so that you may stand on the laminate to complete the top coating. Mix up sufficient top coat to complete the roof with the same amount of catalyst used on the main laminate. Decant a small amount to finish the edges and all details work with a small paint brush and apply the rest to the main roof area with a clean 7" lambswool roller. 

Ensure that the top coat is even and not more than half a mm thick. If the top coat is applied too generously, there is a danger that it will crack. 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. All trims may be painted if required.

When you have prepared the new deck, the
GRP Roofing is carried out in the following sequence.

1: Trimming: Fitting the edge trims.

2: Bandaging: Reinforcing the board joints.

3: Laminating: Applying the GRP membrane.

4: Top Coating: Applying the final top coat.


The trims are supplied in 3m lengths and should be fitted as shown by nailing the bonding edge to the deck. The facia, drip and up stand trims should be bonded to an underlying slate batten (as shown) in order to support the edge. 

The 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 choice of trims is as follows:

Drip facia, used wherever the roof drains into a gutter.

free standing edge wherever no drainage is required.

Used in place of lead wall flashing, usually used with fillet trims.

Fillet trims used wherever a roof meets an abutting wall.

Expansion joint used only on roofs over 100m2.

Flat flashing used mainly as a slate flashing where a pitched roof meets a GRP flat roof.

Should you require a GRP system a full in depth survey can be carried out, on completion a detailed specification detailing the type of materials to be used and our recommendations  along with the guarantee periods available will be submitted, a full quotation will be attached to the specification for your approval, with all GRP systems there are options available from all the main manufactures which carry full guarantees.

( insurance baked guarantees available on request)

The GRP Systems can also be specified for : Warm, Cold, Inverted, Ballast, Balconies with walkway tiles, Green Roofs.

Our Technical staff are on hand to assist clients with technical assistance on all  matters concerning our range of  flat roofing services, whether it be problem solving, specifications or general enquiries.

We offer a full nationwide service for all our clients.   

FIRST CLASS ROOFING SYSTEMS UK are also in the unique position to have our own in house Cad design / Technical department, this enables us to supply detailed drawings for all your requirements.

We are approved installers for many roofing manufacturers, in all instances the products supplied and installed by our company will carry a  full manufacturers guarantee and will be installed by approved and fully trained operatives only.