Flat roofing in Rathfarnham usually comes down to two materials, EPDM rubber and GRP fibreglass, and the right choice depends on your extension, your budget and how exposed your roof is. This guide compares EPDM and GRP for the Irish climate, sets out real 2026 costs, and explains when to repair a flat roof and when to replace it.
Rathfarnham runs from the village up towards the Dublin Mountains, and a lot of its homes carry flat-roof rear extensions. You see them across the 1930s to 1980s semi-detached estates, on Victorian terraces near the village, and on the 1990s and 2000s infill in between.
Those flat-roof extensions are where most of our Rathfarnham flat-roofing work happens, across D14 and D16. Many were built with old felt that has long since brittled and cracked, so a modern EPDM or GRP cover is a genuine upgrade rather than a patch. Every job starts with a proper look at the deck underneath, because the cover is only as good as the timber it sits on.
Rathfarnham sits higher and more exposed than the coastal South Dublin suburbs, so flat roofs here take a beating. There is heavier rainfall to shed, more wind trying to lift the edges, and winter freeze-thaw cycles that open up any crack in an old felt or a tired joint.
Ponding water is the classic Rathfarnham flat-roof problem: rain that sits instead of draining, then works into the smallest split. Old felt roofs blister and crack, GRP can hairline-craze if it was laid badly, and flashing to the house wall pulls away over time. Left alone, a small split lets water into the deck and the ceiling below, and a straightforward recover becomes a full rebuild.
For most Rathfarnham extensions we fit EPDM rubber. It is a single seamless sheet, so there are very few joints to fail, it stays flexible through freeze-thaw, and it copes well with our wet, windy climate. It is quick to install and handles ponding better than most alternatives.
GRP fibreglass is the other strong option. It gives a hard, walkable finish that suits balconies and roofs you want to use, and it looks crisp with a solid trim. The trade-off is that GRP is laid wet on site, so it needs dry conditions and a skilled hand, and a poor lay can craze in the cold. Both materials, fitted properly, will comfortably outlast the old felt they replace.
Every extension is different, but these are honest Rathfarnham ranges for 2026. We give you a written, fixed price after a free survey, so there are no surprises at the end.
What moves the price is the size of the roof, the state of the deck underneath, access, and whether you go for EPDM or a GRP finish. If the timber deck has gone soft from a long-term leak, that gets replaced first, and the survey tells us up front.
We are a CIRI-registered contractor (Construction Industry Register Ireland), so you can check us independently before anyone sets foot on your roof. Every survey is done by a qualified roofer, not a salesperson, and you get a written condition report with a fixed-price quote within 48 hours.
We start by checking the deck and the falls, because a flat roof that ponds needs the drainage sorted, not just a new cover. A typical EPDM extension is done in a day or two, GRP a little longer because it needs dry weather to cure. We weatherproof anything urgent on the first visit, tidy up fully afterwards, and back the work with a written guarantee, so you know the timeline and the disruption before we start.
Learn more about our flat roofingWe cover all of D14 and D16. See our full Rathfarnham roofing service.
For most Irish flat roofs, EPDM rubber is the best all-round choice. It is a single seamless sheet with very few joints to fail, it stays flexible through winter freeze-thaw, and it copes well with heavy rain and wind. GRP fibreglass is an excellent option too where you want a hard, walkable finish, though it needs dry conditions and a skilled installer.
A properly installed EPDM flat roof typically lasts 25 to 30 years or more, and many outlast that. Because it is one seamless sheet with no felt laps to split, there is far less to go wrong than with an old felt roof. Keeping the drainage clear and the flashing sound helps it reach the top of that range.
EPDM flat roofing in Rathfarnham runs about €80 to €120 per square metre supplied and fitted in 2026. A typical small extension recover usually lands between €1,200 and €2,500, depending on size and the state of the deck underneath. You get a written, fixed price after a free survey, so the figure never changes on completion.
Yes, a flat roof can be converted to a pitched roof, and it is a common upgrade on older Dublin extensions. It costs considerably more than recovering the flat roof, because it involves new timber structure, and it often needs planning permission where it changes the roof's shape or height. We assess whether a good EPDM or GRP flat roof would serve you just as well before recommending the bigger job.
Replacing an existing flat roof like for like does not need planning permission in Dublin. You may need it if you change the roof's shape, height or footprint, or if the property is protected or in a conservation area, which affects parts of the Rathfarnham village core. We flag any of that during the free survey so there are no surprises.
Nearby areas we cover
Flat Roofing in Rathfarnham, Dublin South. Free survey, written fixed-price quote, 10-year guarantee.