GRP Fibreglass Roofing for balconies and walkways

GRP, or glass reinforced plastic, is what most people mean when they talk about fibreglass roofing. It is built up in layers on site rather than arriving as a pre-made sheet, which lets it be shaped tightly around upstands, outlets and awkward corners. Once cured it forms one continuous, rigid surface with no joints or seams at all, which is a big part of its appeal on roofs that get regular use.

The build up starts with a layer of resin and matting laminated directly onto a prepared deck, usually marine ply or OSB3, followed by a further layer for strength. Trims at the edges and around upstands are laminated in as part of this process rather than fixed on afterwards, so the whole roof cures as one solid piece. A pigmented topcoat resin goes on last, giving the roof its colour and its UV resistant, weatherproof finish.

Because it forms a genuinely hard, walkable surface, GRP is often the right choice for balconies, roof terraces and access walkways where people will be out on the roof regularly, not just for the odd maintenance visit. It also suits dormer cheeks and small flat sections on pitched roofs where a tidy, seamless finish matters for the look of the building as well as the performance.

Ventilation and movement in the deck below need thinking about before laminating, since GRP is rigid and will crack if the timber underneath flexes too much. We check the deck is properly fixed and stiff enough for the job, and add extra noggins or support where needed rather than laminating over a bouncy deck and hoping for the best.

Weather plays more of a part in GRP installs than with some other systems, since the resin needs the right conditions to cure properly. We plan jobs around this so the laminate goes off correctly rather than rushing it in unsuitable conditions, which is where a lot of botched fibreglass roofs come from.

Costs depend on the roof area, the amount of trim and upstand work involved, and access. A small dormer cheek is a quick job, while a full balcony with drainage outlets and glass balustrade upstands takes more time and materials. All of this is broken down in the free written quote before work starts.

We fit GRP roofs for homeowners across Coventry, Solihull, Warwick, Leamington Spa and Rugby, on everything from garage roofs to balconies over extensions. If your existing GRP roof has gone dull, chalky or has a crack in the topcoat, we can also look at recoating or repairing it rather than starting again from the deck up.