GRP fibreglass roofing across Cardiff

Price per m²

£69–£129

Typical life

20–40 years

Manufacturer guarantees

20–25 year material warranties on specified systems

Typical garage roof

£1,650–£3,000

How much does a GRP fibreglass roof cost in Cardiff?

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

Which flat roofs are common in Cardiff?

Flat roofs in Cardiff sit on terraced streets with flat-roofed rear kitchens and bathrooms, shops with flat-roofed rear stores below flats and 1960s and 1970s link-detached houses with flat-roofed garages and porches. Wales averages roughly 1,460 mm of rain a year, among the wettest in Britain, so we design for steady run-off: proper falls, clear outlets and upstands well above the finished roof. Approximate 1991–2020 regional averages based on Met Office data.

Building regulations in Wales

Welsh guidance is that most re-roofing needs building control approval, so it's worth checking whenever more than a quarter of a roof is replaced or repaired. Renovated roofs are upgraded to around 0.16 W/m²K where feasible, and new extension roofs are built to 0.13 W/m²K under the Welsh Approved Document L. In Cardiff the application goes to Cardiff Council. 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.

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.

Which towns in Cardiff do we cover?

• Cardiff
• Whitchurch

Everything about GRP fibreglass roofing → · All flat roofing in Cardiff →