Wandsworth at a glance
- Postcode districts
- SW18, SW15, SW11, SW17
- Council area
- London Borough of Wandsworth
- Building approval
- London Borough of Wandsworth building control, or a registered building control approver
- Guide price region
- London (+20% on West Midlands rates)
Why choose GRP fibreglass roofing in Wandsworth?
GRP is a good choice in Wandsworth when the roof will be seen or used: a dormer visible from the street, an extension overlooked by upstairs windows, or a roof that needs access for cleaning or maintenance. The hard, jointless finish and moulded trims give a neat result that copes with occasional foot traffic.
Around Wandsworth, flat roofs are common on mansard and dormer loft conversions and on kitchen extensions and roof terraces behind period houses. The Thames basin is one of the drier parts of Britain at roughly 730 mm of rain a year, but summer heat is the bigger test here: dark membranes on south-facing roofs swing a long way in temperature.
How much does a GRP fibreglass roof cost in Wandsworth?
At London guide rates, a 20 m² extension roof in GRP with a new deck and insulation comes to £3,600–£6,450 including VAT. 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 | £3,600–£6,450 |
| Dormer (8 m²), GRP, scaffold | £1,700–£3,200 |
| Single garage (18 m²), GRP fibreglass | £2,150–£3,900 |
| Single garage (18 m²), EPDM rubber | £1,900–£3,350 |
| Extension (20 m²), EPDM, new deck + insulation | £3,350–£5,850 |
Will a new GRP roof need extra insulation to meet building regulations?
If the roof is over a heated room and you are replacing more than half of it, usually yes. In England, Wales and Northern Ireland that counts as renovating a thermal element, and in Scotland the council's building standards service will say whether a building warrant applies.
GRP pairs well with a warm roof because the new deck boards it needs can sit on top of the insulation. The result is thicker, so we check at survey that there is room under door cills and wall flashings, and that the upstands can finish around 150 mm above the new surface. Where approval is needed we arrange it with building control or building standards.
Unheated, detached garages normally sit outside the thermal rules. See the building regulations page for each nation, or the warm vs cold roof guide for why we avoid cold roofs where we can.
What's included?
- Coloured UV-stable topcoat, with anti-slip finish on request
- Moulded GRP trims, kerbs and upstands
- Resin and glass-mat laminate with taped and reinforced joints
- New OSB3 or plywood deck, fixed at close centres
Building regulations in England
Replacing more than half of a flat roof over a heated room usually counts as renovating a thermal element, so the roof is insulated to around 0.16 W/m²K where that's technically and economically feasible, and the work is notified to building control: the council or a registered building control approver, unless a registered competent person self-certifies it. A roof on a new extension is built to 0.15 W/m²K. Patch repairs, and most unheated detached garages, don't trigger the upgrade. Structural changes, or a new covering that adds 15% or more to the roof's weight, also need approval. More on the rules.
Which nearby areas do we also cover?
- Hammersmith and Fulham · 3 mi
- Kensington and Chelsea · 3 mi
- Merton · 4 mi
- Lambeth · 4 mi
- Westminster · 5 mi
- Kingston upon Thames · 5 mi
GRP fibreglass roofing in Wandsworth: questions
Do you cover Wandsworth?
Yes. Wandsworth is part of our London coverage, including postcode districts SW18, SW15, SW11, SW17. Surveys and roofs are carried out by vetted roofing teams working under S&K Property Investments and Improvement Ltd.
Who checks building regulations for a flat roof in Wandsworth?
Where the work needs approval it goes to London Borough of Wandsworth building control, or a registered building control approver. We tell you at the survey whether your job needs it and deal with the paperwork as part of the quote.
How much does a GRP fibreglass roof cost in Wandsworth?
£3,600–£6,450 for a 20 m² extension roof in GRP with a new deck and insulation, at London guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Can a cracked GRP roof be repaired?
Often, yes. The area is ground back, cleaned and re-laminated with fresh mat and topcoat. If cracks keep returning along joints, the deck or detailing usually needs attention rather than another patch.
Does GRP smell when it is being laid?
Yes, the resin gives off a strong styrene smell while it cures. It usually fades within a day or so, and we advise keeping nearby windows closed while the team works.