GRP fibreglass roofing across London

Price per m²

£90–£168

Typical life

20–40 years

Manufacturer guarantees

20–25 year material warranties on specified systems

Typical garage roof

£2,150–£3,900

How much does a GRP fibreglass roof cost in London?

Guide prices including VAT at London rates. The fixed price comes after a free survey for new and replacement roofs.

Which flat roofs are common in London?

Flat roofs in London sit on kitchen extensions and roof terraces behind period houses, mansion blocks and purpose-built flats with large flat roofs and Victorian and Edwardian terraces with flat-roofed back additions. 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. 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 London the application goes to City of Westminster, London Borough of Camden, London Borough of Islington and 29 other councils. More on the rules.

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.

How long does a GRP roof last, and is it guaranteed?

A properly laid GRP roof typically lasts 20 to 40 years. The range is wide because so much depends on the laminate being fully wetted out, the deck staying dry and stable, and the topcoat being renewed if it wears.

When GRP fails early, the cause is usually one of these:

• resin laid in damp or cold conditions that never fully cured;
• cracks at board joints or trims where movement was not allowed for;
• a deck that was wet, soft or poorly fixed before laminating;
• a thin or patchy topcoat that has weathered through.

On guarantees, manufacturer material guarantees are available on many specified GRP systems, and some need a registered build-up or an approved installer. Where registration is possible, we do it for you. Every re-roof also comes with our written workmanship guarantee, with the length set out in your quote, and you can ask about insurance-backed options. Read more in our guarantees guide.

Which towns in London do we cover?

• Westminster
• Camden
• Islington
• Haringey
• Hounslow
• Barnet
• Bexley
• Lambeth
• Croydon
• Havering
• Lewisham
• Redbridge
• Southwark
• Bromley
• Ealing
• Hammersmith and Fulham
• Harrow
• Kensington and Chelsea
• Barking and Dagenham
• Brent
• Greenwich
• Hillingdon
• Kingston upon Thames
• Richmond upon Thames
• Sutton
• Waltham Forest
• Enfield
• Hackney
• Newham
• Tower Hamlets
• Merton
• Wandsworth

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