If you’re replacing a flat garage roof in the UK, the three materials you’ll hear about most are EPDM rubber, felt, and GRP fibreglass. They can all work well — but they suit different budgets, roof shapes, and “how long do I want to forget about it?” expectations.
This guide compares them side-by-side, with realistic cost ranges, lifespan expectations, and the situations where each one makes the most sense.
Quick answer (if you want the short version)
- Best “fit and forget” lifespan: EPDM (often quoted at 50+ years when installed well).
- Best value on a tight budget: Felt (especially torch-on systems), but lifespan depends heavily on spec and install quality.
- Best for a tough, seamless finish on complex details: GRP (fibreglass), typically quoted at 30+ years when installed and maintained properly.
Comparison table: EPDM vs Felt vs GRP
| Material | Typical installed cost (UK, per m²) | Typical lifespan (guide) | Best for | Main downside |
|---|---|---|---|---|
| EPDM rubber | ~£70–£100/m² | 50+ years (often quoted) | Simple flat roofs, long-term durability | Detailing matters at edges/junctions |
| Felt (torch-on) | ~£80–£120/m² (some guides) | ~15–30 years (torch-on often quoted) | Budget-friendly replacements, proven method | Can crack/age sooner if low spec or poor install |
| GRP fibreglass | ~£80–£110/m² (average guide) | 30+ years (often quoted) | Detailed roofs, durable hard surface | Needs correct curing/installation conditions |
Reality check: prices can swing with roof size, access, edge details, and where you live (London/South East often higher). General “standard flat roof” pricing is often quoted around ~£75/m² as a broad guide.
EPDM rubber garage roofs
Pros
- Long lifespan reputation (often quoted 50+ years with good installation).
- Flexible membrane handles movement and temperature changes well
- Often fewer seams (depending on roof size), reducing leak points
- Repairs can be straightforward when damage is localised
Cons
- Bad edge or wall-junction detailing can still cause leaks (it’s rarely the “middle” that fails)
- Not the cheapest option up front in many quotes (though often strong value over time)
Best for
- Most standard single/double garage flat roofs
- Homeowners who want long-term performance and fewer repeat issues
Felt (torch-on or high-performance felt systems)
Pros
- Widely available and familiar to many roofers
- Often competitive pricing and quick turnaround
- Torch-on felt can have a solid lifespan when installed well (often quoted in the 15–30 year range).
Cons
- Lifespan varies a lot depending on specification (cheap felt vs proper multi-layer system)
- More prone to cracks/splits as it ages if the system is poor or detailing is weak
- If your roof has ponding water issues, felt seams can get repeatedly stressed
Best for
- Budget-driven replacements
- Straightforward roofs where you want a reliable, “known” solution
GRP (fibreglass) garage roofs
Pros
- Seamless, hard-wearing finish when installed properly
- Often quoted at 30+ years lifespan potential.
- Great for roofs with lots of trims, corners and details
- Resistant to small punctures compared to some membranes
Cons
- Install quality and conditions matter (curing, layering, detailing)
- Some roofs may develop surface issues over time if poorly applied (you’re buying workmanship here)
Best for
- Garages where you want a strong, rigid finish
- Roofs with awkward detailing where a neat formed finish is important
What usually matters more than the material
In garage roofing, leaks typically come from details and drainage:
- edges and corners
- wall junctions (attached garages)
- outlets/downpipes and ponding water
- poor falls (water sitting on the roof)
If your roof holds water after rain, ask any roofer quoting to explain how they’ll address drainage or detailing — otherwise you can end up “repairing” the same problem again.
“Which should I choose?” (simple decision guide)
| Situation | Best shortlist | Why |
|---|---|---|
| You want the longest lifespan and low hassle | EPDM | Long-life reputation and strong durability |
| You want solid value at a lower upfront cost | Felt (torch-on system) | Proven approach; lifespan depends on spec |
| You want a tough, seamless, neat finish | GRP | Durable formed surface; good for detailing |
| Your garage is attached and leaks at the wall | Any of the three (done properly) | Junction detail matters more than material |
| You’ve had repeated patches and it keeps leaking | Replacement (pick a system + fix drainage) | Stop chasing symptoms; fix root cause |
Cost examples (typical garage sizes)
These are rough “ballpark” totals based on common installed cost per m² guides above. Your quote may differ with access, deck repairs and detailing.
| Garage size | Approx roof area | EPDM @ £70–£100/m² | Felt @ £80–£120/m² | GRP @ £80–£110/m² |
|---|---|---|---|---|
| Single garage (typical) | ~18 m² | £1,260–£1,800 | £1,440–£2,160 | £1,440–£1,980 |
| Double garage (typical) | ~30 m² | £2,100–£3,000 | £2,400–£3,600 | £2,400–£3,300 |
What to ask for in quotes (copy/paste)
- Postcode
- Single or double garage (or rough length × width)
- Current roof type (felt / rubber / fibreglass / unknown)
- Any ponding water? (yes/no)
- Any leaks at the wall junction (attached garage)?
- Ask them to specify: deck condition, edge trims, outlet/drainage detail, and warranty
- Ask for: EPDM vs felt vs GRP price difference (if you’re undecided)
FAQs
Which lasts longer: EPDM, felt or GRP?
Many UK guides quote EPDM at 50+ years when installed properly, GRP often 30+ years, and torch-on felt commonly 15–30 years depending on system quality and install.
Which is cheapest for a garage roof?
Felt is often the cheaper option, but installed costs overlap depending on system specification and local labour rates.
Which is best for a garage that leaks where it meets the house wall?
Any of them can work — the key is a proper junction detail (termination/upstand/flashing). This is one of the most common leak points on attached garages.
Is it worth paying more for EPDM?
If you plan to stay in the property and want long-term value, EPDM often makes sense because of its long-life reputation and low-maintenance nature.
