Fibreglass flat roof repair that bonds into the old roof
Most leaking GRP roofs are not worn out. A crack at a trim, a blister or a tired topcoat lets water in at one spot. We grind the damaged area back to sound laminate, lay new resin and matting into it and finish with topcoat, so the repair becomes part of the roof instead of a patch sitting on top.
Also searched as fibreglass roof repair, GRP roof repair or fixing a cracked fibreglass flat roof on an extension, dormer or balcony.
Updated September 2026
Water coming through now? Ring 085 220 1422, or send a photo to WhatsApp and we will tell you if it looks repairable.
Faults we repair on GRP roofs
Cracks along trims, drip edges and upstands, by far the most common failure
Blisters and bubbles where the laminate has lifted off the deck
Crazed, faded or chalky topcoat that has started to let water in
Leaks around outlets, rooflights and wall junctions
Impact damage from ladders, dropped tools or storm debris
Silicone or bitumen paint on fibreglass stops new resin bonding later. If someone has already tried that, we grind it all off before we start.
Five steps, in this order
Find where the water gets in and check the ply underneath for soft or wet spots
Cut out loose laminate and grind back well past the damage
Clean the area with acetone so the new resin bonds to the old
Lay new resin and matting, lapped onto sound roof all round
Finish with topcoat, then water test the repaired area
If the deck under the damage is rotten, a repair on top will not last. We will show you and price replacing that section of ply.
Repair, recoat or replace?
A repair makes sense when the damage is in one place: a cracked trim, a few blisters, a leak at an outlet. The rest of the roof is sound and still bonded to the deck, so we fix the bad section and leave the rest alone.
A recoat makes sense when the laminate is fine but the topcoat has worn thin across the whole roof. After enough years of sun and rain the surface goes chalky and starts to craze. We clean and key the whole surface and put a new topcoat over it, which gives the roof one even colour again and protects the laminate underneath.
Replacement makes sense when the deck has gone. If water has been getting in for a long time the ply goes soft, and GRP over a soft deck will crack again. In that case we strip it and relay it on new ply, as described on our fibreglass GRP page. On a large, simple roof EPDM or Lava 20 can be the better choice, and we will tell you if yours is one of those.
Wondering what it will cost? Our flat roof repair cost guide sets out 2026 prices for repairs, re-covering and new flat roofs.
Fibreglass roof repair questions we get asked
Can a fibreglass flat roof be repaired, or does it need replacing?
Most can be repaired. If the damage is in one area and the deck underneath is dry and firm, we relaminate that section. It needs replacing when the ply has rotted or the laminate has lifted across large parts of the roof. We check the deck before we price, so you know which one you have.
Can you repair GRP in wet weather?
The damaged area has to be dry for the resin to bond and cure. Resin laid onto a wet roof will not hold, so if the forecast will not settle we book the repair for the first dry spell rather than do it badly on the day.
Will the repair match the rest of the roof?
New topcoat on an older roof is rarely an exact match, because the original colour has faded. On a roof you look at every day, such as a balcony or a low extension, recoating the whole surface gives you one even finish. We will price both so you can choose.
How much does fibreglass roof repair cost?
A localised repair to a crack, blister or trim usually costs €250 to €900. Re-covering a whole 20 to 30 m² roof in new GRP is typically €2,000 to €5,500, depending on the state of the deck. We give a fixed price after a free survey across Kerry, Cork and Limerick.
Is the repair guaranteed?
Yes. Like all of our work, it comes with a written guarantee.
Everything we do on a roof
We cover all three counties: roofers in Kerry, roofers in Cork and roofers in Limerick.
Flat roof systems and the rest
GRP is one of several flat roof systems we lay. If your roof turns out to need more than a repair, these pages explain what each option involves.
Get your fibreglass roof watertight again
Send us a photo or book a survey. We will tell you whether it can be repaired and what it costs. Free survey across Kerry, Cork and Limerick.