Transparent pricing for EPDM, GRP fibreglass and traditional flat roofs — garages, extensions and full house roofs. Updated for 2026.
Flat roof pricing depends primarily on the area to be covered and the material chosen. Modern flat roofing materials — EPDM rubber and GRP fibreglass — offer significantly better performance and longevity than traditional felt, and the price difference is smaller than most homeowners expect.
| Project Type | EPDM Rubber | GRP Fibreglass | 3-Layer Felt |
|---|---|---|---|
| Single garage (approx. 16–20m²) | £600–£1,000 | £700–£1,200 | £400–£700 |
| Double garage (approx. 28–36m²) | £900–£1,500 | £1,100–£1,800 | £600–£1,100 |
| Small extension (approx. 10–15m²) | £500–£900 | £600–£1,100 | £350–£650 |
| Large extension (approx. 20–30m²) | £900–£1,500 | £1,000–£1,800 | £600–£1,100 |
| Flat-roofed bungalow (approx. 60–80m²) | £2,500–£4,000 | £3,000–£5,000 | £1,800–£3,000 |
| Large flat roof house (100m²+) | £4,000–£7,000 | £5,000–£8,000+ | £3,000–£5,000 |
Prices include materials, labour, stripping of old roof covering, new decking where needed and VAT. Scaffolding adds £300–£600 if required.
Lifespan: 25–50 years | Best for: All flat roof applications, particularly larger areas
EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber membrane that is highly flexible, UV resistant and virtually seamless on most applications. It's excellent value for money given its lifespan, easy to repair if damaged, and performs exceptionally well in the UK climate. At A1 Rooflines, EPDM is our recommended choice for most residential flat roofing projects.
Lifespan: 25–40 years | Best for: Extensions with complex detailing, high traffic roof terraces
GRP (Glass Reinforced Plastic) creates a rigid, seamless surface that is extremely hard-wearing. It can be moulded around complex shapes and upstands and produces a smooth, attractive finish. GRP is a premium product — slightly more expensive than EPDM but an excellent choice for visible roofs and roof terraces. Read our full EPDM vs GRP comparison.
Lifespan: 10–20 years | Best for: Budget repairs or temporary solutions
Traditional three-layer felt is the least expensive option upfront but has a significantly shorter lifespan and higher maintenance needs. We generally only recommend felt when there's a specific budget constraint, as the long-term cost over 25 years is higher than EPDM or GRP. Many homeowners come to us having had felt applied by a previous contractor that has already failed after 8–10 years.
A comprehensive flat roof quote from A1 Rooflines includes:
If the existing roof deck (the boards beneath the felt/membrane) is rotten or damaged, it must be replaced before new waterproofing is installed. Decking replacement typically adds £200–£500 to the cost depending on the area affected.
Building Regulations require that when more than 50% of a flat roof covering is replaced, the insulation must be upgraded to current standards. This adds £300–£800+ but significantly improves energy efficiency.
Adding a roof light (such as a flat roof skylight) typically costs £500–£1,200 including fitting. New roof drains and outlets add £100–£300.
A1 Rooflines install EPDM and GRP flat roofs across all of Warwickshire. Free survey, detailed written quote.
Request a Quote 📞 07376 660209A1 Rooflines install EPDM and GRP flat roofs across Coventry, Leamington Spa, Warwick, Rugby and the whole of Warwickshire.
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