GRP, or glass reinforced polyester, is laid wet on site. A layer of resin-soaked fibreglass mat goes over a new timber deck, then a pigmented topcoat, and the whole thing cures into a single rigid skin. There are no seams because there are no sheets. Because it's formed in place it follows awkward details that a sheet membrane struggles with: upstands, outlets, odd corners, changes of level. That's why we use it on so many of the balconies, bay roofs, porches and complicated extension roofs around Totnes.
Where GRP is the right choice in Totnes
- Balconies and roof terraces that get walked on. The topcoat is hard-wearing and we can add an anti-slip finish.
- Roofs with lots of detail: pipes, outlets, soil stacks, rooflights and parapets, where one continuous laminate is easier to make watertight than a sheet with a dozen cut details.
- Bay window roofs, porches and small dormers, which are common on the 1930s semis across Totnes, TQ9 and too fiddly for sheet systems.
- Valley and parapet gutters on larger roofs, where a seamless lining stops the leaks that old lead or felt linings cause.
- Anywhere you want a specific colour or a surface that will be looked at from above, such as a roof below bedroom windows.
For a plain rectangular extension roof that nobody walks on, EPDM is usually better value. We fit both and will tell you which your roof wants.
How a GRP roof is laid properly
GRP is unforgiving of shortcuts, and almost every failed fibreglass roof we see in Totnes comes down to one of three things: an old or damp deck, laying in the wrong weather, or no allowance for expansion. Our process is built around avoiding all three.
- New deck, always. GRP needs a fresh, dry OSB3 deck laid with the right expansion gaps. We don't laminate onto old boards, old felt or chipboard.
- Dry conditions. Resin cures by chemical reaction and needs the right temperature and humidity. We lay GRP in dry weather with the deck fully dry, and we'll move a date rather than lay it in the damp.
- Trims bonded, not just nailed. The pre-formed edge and upstand trims are bedded in resin and laminated over so they become part of the roof.
- Expansion joints on larger roofs so the laminate can move with the deck through the seasons.
- Full-weight laminate. We lay the mat weight the system specifies, usually 600 g, rather than a thin single layer that looks the same on the day and fails later.
- Topcoat applied once the laminate has cured, in your chosen colour, with anti-slip aggregate where the roof will be walked on.
Finishes and colours
Topcoats come in a range of greys, greens, browns and terracotta, plus a lead-grey that works well on period properties in Totnes. Anti-slip finishes suit balconies and access walkways. Because the topcoat is a separate layer it can be refreshed in later years to extend the life of the roof without re-laminating.
Insulation and warm roofs
Like any renewed flat roof, a GRP roof should be built as a warm roof with insulation board over the structural deck and the new OSB deck on top. This is what Building Regulations expect and it stops the condensation that makes cold flat roofs in Totnes damp from the inside. We include it in the quote and handle any Building Control notification.
Guarantees
We use approved GRP systems with a 25-year manufacturer guarantee, backed by our own workmanship guarantee. The paperwork comes with the quote so you can read what's covered before you decide.
GRP for bay roofs, porches and dormers in Totnes
The 1930s semis that line so many streets in Totnes have a bay window at the front with a small flat or shallow-pitched roof over it, and a porch roof beside the door. These little roofs are forgotten until water starts running down the inside of the bay. They're too small and too fiddly for sheet membranes, which is exactly where GRP earns its keep. We strip the old felt or lead, fit a new deck, laminate the whole roof including the upstand against the wall and the drip edge at the front, and finish in a lead-grey topcoat that looks right on a period house. The same applies to flat-roofed dormers on converted lofts across Totnes, TQ9, where the roof, the cheeks and the junction with the main roof can all be laminated as one piece.
Looking after a fibreglass roof
GRP needs very little. Keep the outlets clear so water can get away, sweep off leaves and moss once a year, and avoid dragging heavy or sharp objects across it. If the topcoat dulls after fifteen or twenty years it can be cleaned and re-coated without touching the laminate, which is one of the reasons we recommend it for roofs in Totnes that are visible from upstairs windows. If something does crack it, a GRP roof is easy to repair invisibly, because new laminate bonds chemically to the old.
Fibreglass roofing across Totnes and Totnes, TQ9
Totnes Roofing is based in Totnes and works across Totnes, TQ9 and the surrounding parts of Devon. A typical bay roof or porch takes a day; a balcony or extension roof one to two days. We give written quotes after inspecting the roof, and we photograph the deck and laminate before the topcoat goes on so you can see what's underneath.