Fibreglass Flat Roofs and Repairs
GRP Fibreglass Roofing in Liverpool
GRP fibreglass roofing is a seamless flat roof covering made from glass-reinforced polyester, laid over a new timber deck and sealed with a hard-wearing topcoat. Roofer & Builder installs and repairs GRP roofs on homes and commercial buildings across Liverpool, Merseyside, Wirral and the wider North West.
A fibreglass roof suits extensions, garages, dormers and porches, where a neat, joint-free finish matters. It is one of several systems covered by our flat roofing services, so we can advise honestly on whether GRP, rubber or felt suits your roof best. We always inspect first, then provide a clear written quotation.
What Is GRP Fibreglass Roofing?
GRP stands for glass-reinforced polyester. Glass-fibre matting is saturated with polyester resin and laid over a solid timber deck, typically tongue-and-groove OSB3 boards. As the resin cures it sets hard, forming one rigid layer across the whole roof with no seams or lapped joints. A pigmented topcoat then protects the laminate from daylight and weather and gives the finished colour, which is usually grey.
Edges are formed with pre-moulded GRP trims: drip trims into the gutter, raised kerb trims along open edges and angle trims where the roof meets a wall. Because the trims are laminated in rather than simply nailed on, they become part of the same waterproof layer.
Two things matter more than anything else. The first is the deck: cured GRP is rigid, so soft, damp or poorly fixed boards can lead to cracking later. The second is the weather: the resin needs dry conditions and suitable temperatures to cure, and manufacturers set limits on when their systems can be applied. Rain, heavy dew or cold can spoil the laminate or topcoat, so fibreglass work has to be planned around the forecast.
GRP, EPDM or Felt?
All three systems can give a reliable flat roof when they are installed correctly on a sound deck. The right choice depends on the size, shape and use of the roof, and on your budget. As a broad guide:
| Feature | GRP fibreglass | EPDM rubber | Felt |
|---|---|---|---|
| Material | Glass-fibre matting and polyester resin with a topcoat | Synthetic rubber membrane | Reinforced bitumen membranes |
| How it is laid | Laminated on site over a new deck | Usually one sheet, bonded to the deck with adhesive | Torch-on or cold-applied in layers |
| Joints | Seamless once cured | Few or none on smaller roofs | Lapped joints between sheets |
| Finish | Hard, smooth surface | Flexible black rubber | Usually a mineral-surfaced cap sheet |
| Installation weather | Dry conditions and suitable temperatures to cure | A dry deck for the adhesive | Dry conditions; torch-on uses a naked flame |
| Often used on | Extensions, dormers, porches, garages | Garages, extensions, larger simple roofs | Garages, outbuildings, commercial roofs |
Manufacturers commonly quote long design lives for all three, but in practice the deck, drainage and quality of the detailing usually matter more than the material. You can compare the alternatives on our EPDM rubber roofing and felt roofing pages.
GRP Fibreglass Roofing
Our GRP Roofing Services
New GRP Roofs
Complete fibreglass roofs for extensions, garages and outbuildings, laid on a new deck with moulded trims and a finished topcoat. Falls, outlets and wall junctions are planned first, so water has a clear route off the roof.
Deck Preparation
Where boards are soft, uneven or water damaged, we replace them, check the joists and correct the falls with firrings where needed. This gives the laminate a stable, dry base that will not flex and crack it.
Dormer and Porch Roofs
Small roofs often have awkward details, such as tight upstands, tiled cheeks and narrow edges. GRP can be laminated neatly into these areas, giving dormers, bays and porches a tidy, seamless finish beside the main roof.
Felt-to-GRP Replacement
When an old felt roof has reached the end of its useful life, it can be replaced with fibreglass. We strip the old covering, assess the timbers underneath and install new boards, trims, laminate and topcoat.
GRP Roof Repairs
Cracks at trims, crazed topcoat and impact damage can often be repaired on an otherwise sound GRP roof. We grind back the affected area, re-laminate and re-coat it, and tell you if a deeper deck problem is the cause.
Upstands, Outlets and Edges
Many flat roof leaks start at the details rather than the main surface. We take particular care forming wall upstands, outlets and gutter edges, and check that the flashings above each upstand are sound and well fixed.
How It Works
How We Approach a GRP Roof
Inspect the Existing Roof
We check the covering, deck, joists, falls, outlets and wall junctions before recommending either a repair or a new roof.
Agree the Specification
Your written quotation sets out the deck, trims, topcoat and any upstand or flashing work, so you know what is included before work starts.
Prepare and Laminate
The old covering is stripped, the deck renewed and the trims fixed. Laminate and topcoat go on when the weather allows them to cure properly.
Check and Tidy
We check the edges, outlets and upstands, clear away waste and leave the site tidy, then explain how to look after the roof.
Why Us
Why Choose Roofer & Builder?
More Than 20 Years' Experience
More than 20 years’ roofing experience on flat and pitched roofs means we understand how a flat roof connects to the rest of the building.
Honest Advice on Materials
We do not push one system for every roof. If EPDM or felt would serve you better than fibreglass, we will say so and explain why.
Repair Before Replace
Where a repair will genuinely solve the problem on an existing GRP roof, we recommend it rather than pushing for a replacement.
Roofing and Building in One Team
Joists, firrings, parapet walls and brickwork can be dealt with by the same team when a flat roof leak has affected the structure.
Recognised Accreditations
We are TrustMark registered, NFRC members and a Restec Approved Installer, and we are rated Excellent by our customers on Google.
Free Written Quotations
Every quotation is free, without obligation and set out clearly in writing, so you can compare it and decide in your own time.
Rated as Excellent on Google
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FAQs
GRP Fibreglass Roofing FAQs
Is GRP better than felt for a flat roof?
Not automatically. GRP gives a seamless, hard-wearing finish without lapped joints, which suits many extensions and dormers. Modern felt systems remain a sound choice for many roofs, especially larger ones. The deck, falls and edge details usually make more difference than the material, so we recommend based on your roof.
Can GRP be laid over an existing felt roof?
In most cases, no. Fibreglass needs a clean, dry and rigid deck, and laying it over old felt would trap any defects and moisture underneath. We normally strip the old covering and boards, check the joists and lay a new deck before laminating.
Can you lay a GRP roof in winter?
Sometimes. The resin needs dry conditions and suitable temperatures to cure, so winter work depends on the forecast and on keeping the deck dry. If conditions are unsuitable, the work is rescheduled rather than rushed, and a temporary covering can protect the roof in the meantime.
Can a cracked fibreglass roof be repaired?
Often, yes. Hairline cracks, splits at trims and small areas of damage can usually be ground back, re-laminated and re-coated, although the colour may not match exactly. Cracks that keep returning often point to deck movement or loose trims. Our guide to GRP roof repairs explains more.
Can I walk on a GRP roof?
A properly laid GRP roof will take light foot traffic for maintenance, such as clearing outlets. If it will be used regularly, for example as a balcony or access route, that needs designing in from the start with a suitable deck and an anti-slip finish.
How much does a GRP roof cost?
It depends on the size of the roof, access, the condition of the deck and joists, the number of upstands and outlets, and whether the old roof needs stripping. We provide a free written quotation after inspecting.
Areas We Serve
GRP Fibreglass Roofing Across Merseyside
From our base in Maghull we cover Liverpool and the surrounding towns. Find your local page:
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If there’s something you’d like our team to take a look at, then feel free to contact us. We’re happy to discuss your project and provide a competitive quote.
Head Office
Maghull Business Centre, 1 Liverpool Road North, Maghull, Liverpool L31 2HB
Opening Hours
Office: Mon–Sat 10:00–18:00
Emergency line: 24/7