People often assume a new flat roof is going to become an ongoing chore, resealing every spring, patching after every storm, chasing leaks each winter. That's felt talking. A properly laid GRP fibreglass roof is genuinely one of the lowest-maintenance parts of a house: no seams to reseal, no membrane to patch, and a hard surface that doesn't perish with sun and rain the way older systems do. Here's the honest list of what you should actually do.
What you should do
The whole maintenance routine is basically two visits a year, spring and autumn, with a broom and about ten minutes of your time.
- Clear off leaves, moss and grit a couple of times a year. It's not that they damage the roof (they don't), it's that they hold moisture and can block outlets. A soft brush is all you need. Never a pressure washer.
- Keep the gutters and outlets clear. A blocked outlet is the single most common reason for a flat roof to sit in standing water, and it's the easiest thing on this whole list to fix. Same twice-a-year rhythm.
- Have a quick look after big storms. Not up on the roof, just from a window: anything obviously fallen on it, big branches, dislodged tiles from a neighbouring pitch, any pooling that hasn't drained a day or two later.
- Check the flashings and upstands once a year. Where the roof meets a wall or a chimney is the one bit worth an actual look. If sealants have shrunk or lifted, get them redone before winter, small job, avoids a much bigger one later.
What you don't need to do
A lot of what people assume needs doing simply doesn't, and this is where GRP really pulls ahead of felt or asphalt.
- No repainting or recoating. The coloured topcoat is baked in during the fit, not a paint layer on top. It doesn't peel, flake or need refreshing.
- No annual resealing. There are no joints, laps or seams to reseal, that's the whole point of a seamless system. Felt roofs need this. GRP doesn't.
- No moss treatments. Moss can settle on any surface eventually, but it doesn't damage GRP, and a soft brush deals with it. You don't need chemicals.
- No annual inspections by a roofer. Nothing wrong with getting one, but there's no product warranty condition that requires it. A homeowner's visual check twice a year is usually enough.
Habits that help
A few sensible ones, particularly if the roof gets any foot traffic.
- Don't drag heavy things across it. Ladders, furniture, plant pots, lift them, don't drag them. GRP is tough but a hard object dragged with grit under it can scuff the topcoat.
- Keep sharp things away from it. Metal edges of a folding chair, unshod tripod feet, the corner of a heavy planter. Put a soft mat or offcut of carpet under anything that lives up there.
- No open flame directly on the roof. BBQs and fire pits want a stand or a paving slab under them, not the roof surface itself.
- Rinse it after building work nearby. If a neighbour is having brickwork done or roof tiles replaced, a rinse-off afterwards clears cement dust before it sets in.
- Take a bit more care if it's a terrace. If you're using the roof regularly, our post on walking on a GRP roof goes through the finishes and looking-after tips in more detail.
When to call a professional
Rarely, but there are a few cases where a look from someone experienced is worth the small cost.
- Storm damage, particularly if anything heavy has landed on it or you can see a crack or split from below.
- Any visible dip or soft patch underfoot. That's not the roof itself, it's the deck below softening, and it needs looking at properly.
- A leak, obviously, though a good GRP roof shouldn't leak inside its guarantee. If it does, the workmanship warranty covers it.
- Any of the classic warning signs from our guide on the signs a flat roof needs replacing. On a GRP roof these mostly don't happen for decades, but worth knowing what to look for.
The long-term picture
The reason a GRP roof lasts 30 to 40 years isn't magic. It's that the material itself doesn't degrade the way felt does under sun and rain, and because there are no joints, there's nothing weakening year on year. Add the twice-yearly leaf sweep, and you've done everything you need to do.
Considering a new roof, or looking after an existing GRP one? We're happy to have a look and give you an honest opinion, no pressure.
Free, fixed-price quote. Call 07976 730433 or request one here.
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