Fibreglass
GRP Fibreglass Flat Roofs
A GRP fibreglass flat roof costs €75 to €140 a m² laid, or €2,800 to €6,500 for an extension or garage. It needs dry weather above 10°C to cure, and lasts 25 to 35 years.
What GRP is, the weather it needs, and what it costs.
Free, no obligation. One local company prices it, not five.
What a new flat roof costs for your size
Two taps: the membrane and roughly how big the roof is. The deck, insulation, rooflights and access move the price.
Your roof area × the typical rate
€2,250 to €4,200
30 m² at €75 to €140 a m² for grp fibreglass, laid. An estimate, not a quote.
- A kitchen extension, 25 to 40 m², is €3,000 to €6,500 for the whole job.
- A rotten deck adds €30 to €50 a m².
- Repair and roofing work on a house is at 13.5% VAT, not 23%.
What GRP is
GRP is glass-reinforced polyester: a glass-fibre mat laid on the deck and wetted out with resin, which cures into one hard sheet with no joints. A coloured topcoat goes on last. Pre-formed GRP trims finish the edges and the upstands. It needs temperatures above 10°C to cure properly, so most GRP roofs are laid from spring to early autumn, and it cures in about 4 to 6 hours at 15°C or more.
- For: hard enough to walk on, so it suits balconies and roofs you need to reach; no joints; takes a coloured topcoat; neat trims.
- Against: weather-dependent to lay; it can crack where the deck moves, at board joints and trims, if the deck isn't right; it's less forgiving of poor workmanship.
- In winter, ask whether the job will wait for a warmer spell, or which other membrane is offered.
For more on GRP alone, see fibreglassroofing.ie.
What a GRP roof costs
| Job | Typical cost | What moves the price |
|---|---|---|
| GRP fibreglass, extension or garage | €2,800 to €6,500 | Dry, mild weather to cure; trims |
| Rear kitchen extension, 30 to 40 m², GRP | €3,800 to €6,500 | Trims, a rooflight |
| GRP, a m² | €75 to €140 a m² | Laid, with topcoat |
Flat roof jobs we cover
Flat roof replacementExtensions, garages and dormers. €3,000 to €6,500 on a kitchen extension.More on flat roof replacement →
Flat roof repairLeaks, blisters, split seams, outlets. €250 to €900.More on flat roof repair →
EPDM rubber roofsOne sheet, no flame. €70 to €140 a m² laid.More on epdm rubber roofs →
Torch-on felt roofsThe lowest cost. €55 to €90 a m² laid.More on torch-on felt roofs →
Warm flat roofsInsulation above the deck. €130 to €190 a m².More on warm flat roofs →Flat roofs in every county
- Carlow1.4% flat main roofs
- Cavan0.8% flat main roofs
- Clare1.2% flat main roofs
- Cork2.5% flat main roofs
- Donegal1.0% flat main roofs
- Dublin3.0% flat main roofs
- Galway1.2% flat main roofs
- Kerry1.8% flat main roofs
- Kildare1.0% flat main roofs
- Kilkenny1.4% flat main roofs
- Laois1.2% flat main roofs
- Leitrim1.2% flat main roofs
- Limerick1.6% flat main roofs
- Longford0.9% flat main roofs
- Louth2.3% flat main roofs
- Mayo2.3% flat main roofs
- Meath1.3% flat main roofs
- Monaghan0.9% flat main roofs
- Offaly1.3% flat main roofs
- Roscommon1.2% flat main roofs
- Sligo1.4% flat main roofs
- Tipperary1.6% flat main roofs
- Waterford2.2% flat main roofs
- Westmeath1.5% flat main roofs
- Wexford2.7% flat main roofs
- Wicklow2.7% flat main roofs
Free quote
Get a price in 4 taps
Tap what you need and leave your number. It goes to one flat roofing company that covers your county, and they ring you back to arrange a look and a written price.
Questions people ask
How long does a fibreglass roof last?
25 to 35 years when it's laid on a sound deck in the right weather.
Can GRP be laid in winter?
It needs dry weather above 10°C to cure. On a mild dry winter day it's possible; often the job waits.
Is GRP better than EPDM?
GRP can be walked on and takes a colour. EPDM goes down in any season without a flame or curing. Prices are close: see the comparison.
Why do fibreglass roofs crack?
Mostly where the deck moves underneath: board joints, the trims and the junction with the wall. A sound, well-fixed deck is the fix.
Get a free price for your flat roof
One local flat roofing company, a look at the roof, a written price. Free, no obligation.