EPDM vs GRP vs felt: which flat roof suits your Teesside property?
EPDM rubber is the default for most Teesside flat roofs: single sheet, no seams, 20 to 30-year life, £900 to £1,800 for a garage. GRP fibreglass gives a harder, walkable, good-looking finish for balconies and visible roofs at a similar price. Modern torch-on felt is the budget option, far better than its reputation but still the shortest-lived of the three.
Last updated: August 2026.
The short version
All three systems keep water out on day one; they differ in how long they keep doing it, how they look, what they tolerate, and what they cost. The right choice follows from what the roof covers, whether anyone will walk on it, and whether you will see it from an upstairs window, so this guide works through each before scoring them head to head.
EPDM rubber: the default answer
A synthetic rubber membrane, usually laid in a single sheet cut to the roof's exact size. No seams means no seam failures, the most common flat-roof leak of all simply has nowhere to start. EPDM tolerates standing water, flexes through Teesside's freeze-thaw winters without cracking, and lasts a realistic 20 to 30 years with long manufacturer warranties. It looks utilitarian, a black sheet, which matters on roofs visible from above and not at all on the average garage. For most Teesside garages, extensions and dormers at £900 to £3,000 depending on size, it is the right default.
GRP fibreglass: the good-looker
A resin and glass-fibre laminate applied wet and curing into a hard, jointless shell. The finish is excellent, smooth, coloured, walkable, and the natural choice for balconies, walkways and flat roofs you will actually see. Weaknesses are honest ones: GRP is rigid, so it dislikes roofs that flex or move; installation is weather-fussy and skill-sensitive, and a bad GRP job fails early at the edges and trims. Price sits close to EPDM on most Teesside jobs, with the detailing skill of the installer mattering more than the material itself.
Torch-on felt: the budget survivor
Modern three-layer torch-on felt is not the 1980s material that gave flat roofs their reputation: the capsheets are tougher, the laps are welded, and a well-laid felt roof now delivers 10 to 15 years reliably. It remains the cheapest of the three, typically 15 to 25 percent under EPDM, and it repairs easily. It also remains the shortest-lived, the most dependent on installation heat-welding being done right, and the least tolerant of ponding. For tight budgets and simple roofs it is a legitimate choice; for a roof you want to forget about for three decades, it is not.
Head to head
| Factor | EPDM | GRP | Torch-on felt |
|---|---|---|---|
| Garage roof, typical | £900–£1,400 | £1,000–£1,500 | £700–£1,200 |
| Extension roof, typical | £1,400–£3,000 | £1,500–£3,200 | £1,100–£2,500 |
| Working life | 20–30 years | 20–30 years | 10–15 years |
| Seams | None (single sheet) | None (wet-laid) | Welded laps |
| Tolerates ponding | Excellent | Good | Poor |
| Walkable | Occasionally | Yes | Occasionally |
| Visible finish | Plain black | Excellent, coloured | Mineral or plain |
| Installation sensitivity | Low | High | Medium |
| Repairs | Patchable | Patchable, visible | Easiest |
The Teesside shorthand
Garage or hidden extension roof you want to fit and forget: EPDM. Balcony, walkway, or a roof visible from the house: GRP, with the installer's track record checked hard. Tight budget on a simple roof: modern felt, from someone who does it properly. Whichever system, the deck and the detailing decide the outcome, and the quote should state both. The cost guide prices every combination, and the flat roofing page covers the process.