- Price per m²
- £77–£144
- Typical life
- 20–40 years
- Manufacturer guarantees
- 20–25 year material warranties on specified systems
- Typical garage roof
- £1,850–£3,350
Somerset at a glance
- Largest towns
- Bath, Weston-super-Mare, Taunton, Yeovil
- Postcode areas
- BA, BS, TA
- Building control
- Bath & North East Somerset Council, North Somerset Council and Somerset Council
- Neighbouring areas
- Bristol · Wiltshire · Gloucestershire · Dorset
- Guide price region
- South West (+3% on West Midlands rates)
How much does a GRP fibreglass roof cost in Somerset?
Guide prices including VAT at South West rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), GRP, new deck + insulation | £3,100–£5,550 |
| Dormer (8 m²), GRP, scaffold | £1,450–£2,750 |
| Single garage (18 m²), GRP fibreglass | £1,850–£3,350 |
| Single garage (18 m²), EPDM rubber | £1,650–£2,900 |
| Extension (20 m²), EPDM, new deck + insulation | £2,900–£5,050 |
Which flat roofs are common in Somerset?
Flat roofs in Somerset sit on newer estates where the first extension roofs are now being replaced, lock-up garage blocks on estates and terraced streets with flat-roofed rear kitchens and bathrooms. The South West averages roughly 1,260 mm of rain a year and many roofs face wind off the Atlantic, so we specify fixings and edge details for wind uplift as well as drainage. Approximate 1991–2020 regional averages based on Met Office data.
Building regulations in England
Replacing more than half of a roof over a heated room usually counts as renovating a thermal element, so it is insulated to current standards and notified to building control. Renovated roofs over heated rooms are insulated to around 0.16 W/m²K where that's feasible, and new extension roofs are built to 0.15 W/m²K. In Somerset the application goes to Bath & North East Somerset Council, North Somerset Council and Somerset Council. More on the rules.
Why do GRP roofs crack, and can weather affect the installation?
GRP usually cracks where the structure moves and the laminate cannot, typically along board joints, at the junction with trims, or where a roof meets a wall. Weather during laying is the other big factor, because resin cures by chemical reaction and that reaction is sensitive to temperature and moisture.
How we reduce the risk of cracking:
- boards fixed at close centres so the deck does not flex;
- joints taped and reinforced with an extra strip of mat;
- wall junctions finished with a separate trim or flashing, not laminated hard into the masonry;
- roofs over a certain size divided with movement details where the system calls for them.
And how weather is managed:
- no laminating in rain, on a damp deck, or when dew or frost is likely before the resin sets;
- catalyst levels adjusted for the temperature, so resin neither stays tacky on a cold day nor kicks too fast in summer heat;
- the roof sheeted over if a shower threatens a fresh laminate.
That is why a GRP date can move at short notice. A day's delay costs far less than a laminate that never cures properly.
Is GRP better than EPDM, felt or a liquid roof?
GRP is the better choice when you want a rigid, walkable finish, a neat look on a visible roof, or crisp moulded details on a complicated shape. It is not automatically better on a plain garage that nobody steps on.
Strengths: hard surface that takes occasional foot traffic; jointless finish with no laps; trims, kerbs and upstands moulded as part of the roof; choice of topcoat colours; small repairs can be laminated in.
Weaknesses: sensitive to weather while laying; rigid, so it can crack where the structure moves; usually needs a new deck; styrene smell during application; skill-dependent, so workmanship matters more than with sheet systems.
For a simple roof, EPDM rubber is often quicker to lay and more forgiving of movement. Torch-on felt is usually cheaper per square metre. A liquid-applied roof can go over a sound existing surface, larger commercial roofs tend to suit single-ply, and older buildings may already have mastic asphalt worth keeping. The EPDM vs GRP vs felt guide compares the three most common choices.
Which towns in Somerset do we cover?
GRP fibreglass roofing in Somerset: questions
Which towns in Somerset do you cover?
All of Somerset. The main towns have their own pages below, and if yours isn't listed we still cover it: send your postcode and we'll confirm.
How much does a GRP fibreglass roof cost in Somerset?
£3,100–£5,550 for a 20 m² extension roof in GRP with a new deck and insulation, at South West guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Which postcode areas do you cover in Somerset?
All of Somerset, including the BA, BS, TA postcode areas. Send your full postcode and we'll confirm.
Can GRP be laid over an existing felt roof?
Generally no. GRP needs a clean, dry, rigid timber deck, so the old felt is usually stripped and the boards replaced before laminating.
Is GRP suitable for a dormer roof?
Yes, GRP is commonly used on dormers because the trims can be moulded neatly and the finish looks tidy from the ground. Scaffold is normally needed, which we include in the quote.
Can you walk on a GRP roof?
Yes, a correctly laid GRP roof takes occasional foot traffic, such as cleaning windows or maintaining plant. For a regular walkway or terrace, an anti-slip topcoat and a suitable specification are needed.
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