If you're replacing a flat roof, you'll come across three main options: felt, EPDM rubber, and GRP fibreglass. They all keep the rain out, but they don't cost the same, last the same, or look the same. Here's a fair rundown of each, including where the cheaper options genuinely make sense, so you can decide what's right for your roof.
Felt (built-up or torch-on)
Felt is the traditional flat-roof covering, and it's still the cheapest way to cover a roof today. It's quick to lay, widely available, and if budget is the only consideration it will do a job.
The catch is lifespan. Felt is laid in overlapping layers, and those overlaps, plus the surface itself, are prone to blistering, cracking and lifting as the material ages and the sun gets to it. Most felt roofs need attention within 10 to 15 years, and torch-on systems involve a naked flame during fitting, which isn't ideal near timber and fascias.
- Best for: tight budgets, outbuildings, or a short-term fix.
- Watch out for: seams and blistering, and a shorter life than the alternatives.
EPDM rubber
EPDM is a single rubber membrane, often laid in one sheet and bonded down. It's a real step up from felt: it flexes with temperature, has no naked flame in the fitting, and a good EPDM roof can last around 20 years.
Where it's less ideal is the detailing. The membrane itself may be one piece, but the joints, corners and upstands are bonded and taped, and those are the spots that tend to need attention over time. It's also a softer surface, so it's more easily punctured by a dropped tool or a dragged ladder, and many people find the matt black finish a bit utilitarian.
- Best for: larger simple roofs with few obstacles, on a middling budget.
- Watch out for: bonded joints at the details, and puncture risk.
GRP fibreglass
GRP (glass-reinforced plastic, the same fibreglass used on boat hulls) is what we fit, so we'll be upfront about our bias, but the reasons are straightforward. It's built up wet, in place, into one continuous sheet with no joints anywhere, then finished with a hard, coloured topcoat. There's nothing to peel, lift or come unstuck, which is why a well-laid GRP roof lasts 30 to 40 years and comes with a 25-year written guarantee.
It's tough enough to walk on straight away, comes in 92 colours with a smooth or non-slip finish, and needs next to no maintenance. The trade-offs are honest ones: it costs more than felt, it's a more skilled fit, and the resin needs dry, reasonably warm weather to cure properly, so timing matters. If your existing roof structure is sound, a GRP overlay can sometimes go straight over the top, which keeps the cost and disruption down.
- Best for: homeowners who want to fit it once and forget about it, and anyone who cares how the roof looks.
- Watch out for: a higher up-front price, and the need for a skilled installer and decent weather.
The honest summary
There's no single "best" flat roof, only the best one for your budget, your building and how long you plan to be there. We're happy to give you a straight opinion on all three for your specific roof, even if that means telling you a repair will do for now. Have a look at why people choose us, or just get us out for a look.
Free, fixed-price quote, no pressure. Call 07976 730433 or request one here.
← Back to the blog