GRP fibreglass roofing in Sussex and Surrey

What is GRP roofing?

GRP means glass reinforced plastic. A layer of glass fibre matting is laid onto a prepared deck and wetted out with resin, which cures into a rigid, seamless laminate. A topcoat is then applied to protect it from the weather and give the finished colour. Because the whole roof is formed on site, there are no joints to fail, and corners, upstands and outlets become part of one continuous surface.

Where GRP is the right choice

• Balconies and terraces, where the roof will be walked on, often with an anti slip finish
• Dormers and bay roofs with many corners and edges
• Roofs with rooflights, vents or pipes that need neat, watertight detailing
• Homes where appearance matters, as the topcoat comes in a range of colours

GRP compared with EPDM

Neither is better in every case. We will recommend the one that suits your roof and explain why. You can read the full comparison in our guide to EPDM vs GRP vs felt.

How we lay a GRP roof

1. Strip the old roof and check the deck, replacing any rotten boards.
2. Lay a vapour control layer and insulation with falls built in, for a warm deck where appropriate.
3. Fix a new, suitable deck board and tape the joints.
4. Fit preformed GRP edge trims and corners.
5. Laminate the roof with resin and glass fibre matting, working each detail carefully.
6. Apply the topcoat once the laminate has cured.
7. Check every edge and outlet, clear the site and photograph the finished roof.

Why weather matters with GRP

Resin needs dry conditions and suitable temperatures to cure properly. Rain or damp on the deck during laying is the most common cause of GRP problems. We plan GRP work around the forecast and keep the roof protected until the laminate is ready. That sometimes means waiting a day, which is always better than rushing.

Balconies and walk on roofs

If people will walk on the roof, it needs to be designed for it: a suitable deck, the right laminate and an anti slip topcoat. Balconies also need safe edge protection and correctly detailed door thresholds. We discuss all of this at the survey.

GRP near you

See flat roofing in East Grinstead and flat roofing in Crawley, or our main flat roofing page.

What materials make up a GRP roof?

A GRP roof starts with a firm, dry deck, usually suitable boards fixed securely to the joists, or insulation and a deck on top for a warm roof. Edge trims are fixed first. A resin is then applied, a chopped strand glass fibre mat is laid in it and rolled out with more resin until fully wetted. Once the laminate has cured, a topcoat gives the colour and the weather resistant surface. The quality comes from the deck preparation, the right weight of mat and careful rolling to remove air.

Warning signs that a GRP roof has been laid badly

• Cracks along board joints, showing the deck has moved
• Patches that look white or dry where the mat was not fully wetted
• Bubbles or blisters in the surface
• Topcoat peeling or wearing through
• Leaks at trims or around roof lights

These problems usually come down to workmanship or weather during installation.

GRP for dormers, porches and bay roofs

Small roofs with lots of edges and details are where GRP really shines. Because it is laid wet and cures into one piece, it wraps neatly around corners and upstands. Dormer roofs, porch canopies and bay roofs all benefit from the clean, seamless finish.

GRP on East Grinstead and Crawley homes

In East Grinstead, many homeowners choose GRP for dormers and porches on older houses because the finish can be kept discreet. In Crawley, GRP is popular on rear extensions and on balconies above garages. Where a roof will be used as a balcony, planning permission and Building Regulations for guarding usually apply. See flat roofing in East Grinstead and flat roofing in Crawley.

Step by step: replacing a failed roof with GRP

1. Strip the old covering
2. Replace any damaged or unsuitable deck boards
3. Add insulation for a warm roof where required
4. Fix trims and prepare joints
5. Lay the laminate and allow it to cure
6. Apply the topcoat
7. Check outlets and clear the site

What affects the price of a GRP roof?

As a guide, GRP roofs in the South East usually cost between £90 and £140 per square metre, so a single garage roof is typically from £1,700, with balconies and detailed roofs costing more. Size, insulation, deck condition, details such as roof lights and upstands, and access. Priced after a free survey. Read EPDM vs GRP vs felt. Your exact price is confirmed in writing after a free survey.

Frequently asked questions

Get a quote for a GRP roof

Call 01342 445004, WhatsApp 07939 862 818, or request a free survey.