GRP Flat Roofing Costs in Ireland
What fibreglass costs per m², how it compares to EPDM and felt, and when it's the right call for an Irish extension, dormer or garage.
What fibreglass costs per m², how it compares to EPDM and felt, and when it's the right call for an Irish extension, dormer or garage.
Flat Roof Crack Repair Done Right in Limerick City Centre
GRP stands for Glass Reinforced Plastic, the same material used for boat hulls. On a roof it goes down as a liquid polyester resin, worked into chopped-strand fibreglass matting, then finished with a pigmented topcoat. Once it cures, you have a single rigid shell bonded to the deck underneath. There are no seams, no welds and no laps. That is its main selling point over felt and its real difference from EPDM, which is a rubber sheet dressed in place.
For Irish homes, GRP is most commonly specified on kitchen extensions, dormer cheeks and tops, garage roofs, porch roofs and small commercial units, anywhere flat or near-flat where a minimum fall of 1:40 can be achieved.
Indicative installed rates for 2026, Ireland-wide:
Indicative 2026 price range, Ireland-wide, in euro. VAT at 13.5% extra.
| System | Installed rate | Lifespan |
|---|---|---|
| GRP fibreglass | €90-€140/m² | 25-30 years |
| EPDM rubber membrane | €90-€140/m² | 25-35 years |
| Traditional felt (3-layer) | not recommended for new work | 15-20 years |
Where the existing deck has deteriorated, replacement adds roughly €30-€50/m² across the affected area. VAT at 13.5% applies on top of all figures. Your written quote is the number that counts.
What moves the price within the €90-€140 band:
On most Irish extensions, GRP and EPDM are both sound 25-year-plus systems. The choice comes down to the shape of the roof and the installer in front of you.
GRP suits:
EPDM suits:
Felt we no longer recommend for new work. It is a 15-20 year system against 25-30 for GRP and 25-35 for EPDM. If you are already paying for scaffolding, trims and labour, the covering is the smallest line on the quote. Specifying felt to save a few hundred euro costs you a decade of service life. See our wider guide to flat roofing systems for a fuller comparison.
25-30 years when it is laid properly on a dry, sound deck. Three things decide whether a GRP roof reaches its design life in Irish conditions:
This is where most flat roof quotes diverge. The covering is the headline price; the deck is the hidden one.
If your existing flat roof is felt from the 1990s or 2000s, there is a very good chance the deck underneath is chipboard, and a very good chance water has already reached it. Chipboard swells and crumbles; you cannot lay GRP on it.
A proper quote tells you which it is before the job starts, not after the old covering comes off. We go up and open a corner so the quote reflects reality. The price quoted is the price paid.
Three things specific to Ireland matter:
Rainfall. Dublin averages around 750mm a year; Galway and west Cork clear 1,200mm. Falls and outlet sizing matter more here than in drier climates. A 1:40 minimum fall is standard; 1:60 is common on older extensions, and it ponds. GRP tolerates occasional ponding but hates permanent ponding. If your deck will not give a true 1:40, that needs to be priced in.
Wind. Coastal Galway and west Cork see sustained Atlantic exposure. Edge trims and perimeter fixings have to be specified and fitted correctly or they lift. This is the single most common failure we see on cheaper GRP installs along the coast.
UV and thermal cycling. A pigmented topcoat is not optional in Ireland. Bare resin yellows and degrades under UV. Specify topcoat on every quote, including on hidden gutters and parapet tops.
Yes, and it is one of GRP's practical advantages over EPDM. Localised damage, cracks around upstands or failed topcoat can be ground back and patched in with fresh resin and matting. The repair bonds chemically to the original and, done correctly, is invisible.
Typical repair costs sit in the €400-€2,500 range for most small-area work, rising where scaffolding is needed or the deck has to be opened. A written quote after a proper inspection is the only honest answer. Repairs carry a written guarantee of a minimum of 3 years, rising to 10 years on major repair work.
GRP is less forgiving than EPDM. Resin ratios, matting consolidation, trim detailing and the weather window all have to be right. A roofer doing one GRP job every six months will miss things a specialist will not.
Questions worth asking any installer:
Recommended Roofing carries €6.5 million public liability and €13 million employer liability, is CIRI registered, Guaranteed Irish, and a member of the National Guild of Master Craftsmen. Our crews are directly employed; we do not subcontract.
Every flat roof job we do is backed in writing before any contract is signed:
These guarantees are automatic. They are not upsells, not registrations and not extended-warranty products. Every replacement job carries them by default. See our customer reviews and case studies for real examples.
If you are looking at a flat roof job elsewhere, these city-specific guides cover the same ground with local detail:
If you are weighing up a flat roof replacement or a new extension cover in Dublin, Cork, Limerick or Galway, we will come out, go into the attic or lift a corner, and give you a written fixed-price quote with the deck condition and covering specified clearly. The quote is free, no-obligation, and the price on it is the price you pay. Contact us to arrange a free written quote, or call us: Cork 021 2040925, Limerick 061 788600, Galway 091 622895.
The indicative installed rate is €90-€140/m² for 2026, before VAT at 13.5%. Smaller roofs, complex edge detail and deck replacement all push the price toward the top of that range. Your written quote after an on-site inspection is the only firm figure.
25-30 years when laid correctly on a sound, dry deck. The biggest factors are deck condition at the time of installation and whether the resin was laid in suitable weather. Poor installation on a wet or soft deck significantly shortens that life.
Neither is universally better. GRP suits complex shapes, upstands and walk-on finishes; EPDM suits large simple rectangles and tighter weather windows. Both give 25 or more years when installed properly. The quality of the installer matters more than the material choice.
Deck replacement adds roughly €30-€50/m² on top of the covering rate. On extensions built before 2010 with chipboard decks, assume at least partial replacement will be needed until the deck has been opened and checked.
Yes. Localised cracks, damaged upstands and failed topcoat can be ground back and patched with fresh resin. The repair bonds chemically to the original. Typical small-area repair costs are in the €400-€2,500 range, before VAT.
Full replacement work carries a 10-year written workmanship guarantee plus a Lifetime Leak Guarantee. Repair work carries a minimum 3-year guarantee, rising to 10 years on major repairs. All guarantees are written and automatic, not conditional on registration.
Most ground-floor and modest first-floor flat roofs do not need scaffolding. It is priced in where the building is very high or on a busy pedestrian street where public protection is needed. Where scaffolding is required, it is a separate line on the quote, and you are welcome to source it yourself.
Yes. VAT at 13.5% applies on top of all roofing costs. All published ranges are before VAT.
Occasionally, for maintenance or cleaning gutters, yes. For regular foot traffic such as a roof terrace, specify a heavier-duty anti-slip topcoat at quote stage and discuss the deck loading with your installer.
Properly laid GRP on a stable deck does not crack in normal service. Hairline crazing occurs when resin is laid too thin, in bad weather, or over a deck that flexes. These are installer errors, not material failures.
Replacing an existing flat roof like-for-like generally does not. A new extension that includes a flat roof falls under normal planning rules. Protected structures and Architectural Conservation Area properties require a separate conversation with your local authority.
Ask whether their own crew will do the work or whether it is subcontracted, ask for their CIRI registration number and check it at ciri.ie, ask for written insurance figures, and get the guarantee in writing before signing anything. A contractor who does not want to be checked is telling you something.
Roof Repairs in Ireland. Free survey, written fixed-price quote, 10-year guarantee.