"How long will it last?" is the first thing nearly everyone asks us, and it's exactly the right question. A flat roof isn't something you want to be thinking about again in a few years, so here's an honest answer rather than a sales one.
The short answer
A GRP fibreglass roof that's been laid properly will usually give you 30 to 40 years, and often more. We guarantee ours for 25 years in writing, covering both the materials and the workmanship, but that figure is deliberately cautious. Fitted well, fibreglass tends to outlast the paperwork.
For a bit of context: traditional felt is generally good for 10 to 15 years before it starts to blister and split, and a rubber (EPDM) membrane tends to manage around 20. So even at the careful end of the estimate, GRP is the kind of roof you sort once instead of every decade.
Why it lasts so long
It comes down to one word: seams. Felt is laid in overlapping sheets and rubber is a membrane with bonded joints, and it's almost always those joins, and the detailing around edges and pipes, that give up first. GRP is different. It's built up wet, in place, as one continuous sheet of fibreglass and resin that cures into a single hard shell with no joints anywhere for water to find. Nothing to lift, nothing to peel, nothing to come unstuck.
That shell is also tough enough to walk on from day one, so it copes with ladders, foot traffic and the odd bit of maintenance without being damaged.
What actually affects the lifespan
Here's the honest part: not every GRP roof is equal, and the biggest variable is the fit, not the material. The things that make the difference are:
- The preparation. A sound, dry, properly fixed deck is everything. Rushing this is where cheap jobs fail.
- The weather on the day. Resin needs dry, reasonably warm conditions to cure correctly, which is why the drier months are the ideal window to have a roof fitted.
- The detailing. Edges, upstands, outlets and around any pipework are where skill shows. Get these right and the roof simply doesn't leak.
- The deck underneath. A good roof laid over tired, damp or springy boards won't reach its potential. Sometimes the decking needs replacing first, and we'll always tell you straight if it does.
What about maintenance?
Next to none, which is a large part of the appeal. Clear leaves and debris away from the outlets once or twice a year so water can drain, and give it a look after a big storm. That's genuinely it. There's no re-coating on a schedule, no annual patching, no felt to keep an eye on.
Repair, or replace?
If your current roof is felt, only a few years old, and has one small leak, a repair may be all you need, and we'll happily say so. But if it's been patched more than once, or you're chasing the same leak every winter, you're usually throwing good money after bad. That's the point where a new GRP flat roof pays for itself in peace of mind. If you're not sure which camp you're in, our post on the signs a flat roof needs replacing is a good place to start.
The bottom line
A GRP roof is a genuine long-term fix, not a patch. Fitted properly, it's very likely the last flat roof that part of your home will ever need. The only real variable is who lays it, so it's worth having someone come out, look at what you've actually got, and give you an honest steer.
That's what we do, for free, with a fixed price and no pushy follow-ups. Give us a ring on 07976 730433 or request a quote here.
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