Flat Roof Repairs Dublin — Felt, GRP & Single-Ply

Walk down almost any Dublin street and you'll find flat roofs everywhere — kitchen extensions, dormer conversions, garages, bay window canopies, entire apartment blocks. They're cheap to build, quick to install, and by far the most common thing to go wrong on an otherwise sound house.

The problem is that most flat roof "repairs" only fix the symptom. A blister gets patched, a crack gets sealed over, and it fails again in eighteen months — because the actual cause was never dealt with.

Mr Roofing repairs and replaces flat roofs across Dublin — felt, GRP fibreglass, and single-ply membrane systems, on extensions, garages, and full roofs. Free inspection, 25-year guarantee, and we'll tell you honestly if a repair will genuinely hold or if you're better off replacing the section properly.

Leaking Flat Roofs

Water finding its way in somewhere it shouldn't. We trace the real entry point — which is often nowhere near where the stain shows up inside — before touching anything.

Ponding & Pooling Water

Water sitting instead of draining is the single biggest cause of flat roof failure in Dublin. We fix the fall, not just the symptom underneath it.

Blistering & Bubbling Felt

Trapped moisture or air under old felt roofing, breaking down the surface from below. Left alone, it splits.

Cracked GRP / Fibreglass

UV and thermal movement cracking the surface over time. We repair or overlay depending on how far it's gone.

Full Flat Roof Replacement

Felt, GRP, or single-ply membrane — replaced properly, including fixing whatever caused the original roof to fail.

Garage & Extension Flat Roofs

The most common flat roof job in Dublin, and often the most neglected — out of sight, rarely inspected, until it isn't.

"Ponding water" isn't really about rain — it's about fall.

A flat roof isn't actually flat. It's built with a slight slope — called the fall — that sends rainwater to an outlet instead of letting it sit. Every flat roof needs this, and a huge number of Dublin flat roofs, especially on older extensions, were built without enough of it, or with the fall running the wrong way entirely.

Water that sits on a flat roof rather than draining does two things: it puts far more weight and pressure on the membrane than it was designed for, and it gives moisture far more time to find any tiny weak point and work its way through. A flat roof with the right fall can last decades. One without it can start failing within a handful of years, no matter how good the felt or fibreglass laid on top of it is.

Warm roof vs cold roof — the decision that actually determines how long it lasts.

This is the part almost nobody explains, and it's the single biggest factor in how long a flat roof replacement actually lasts.

A cold roof has the insulation below the roof deck, in the ceiling void — the traditional way flat roofs were built for decades. The problem is warm, moist air from inside the house rises and hits the cold underside of the roof deck, and condenses. Over years, that trapped condensation rots the timber deck from underneath, invisibly, while the roof surface above looks completely fine.

A warm roof puts the insulation above the deck, under the waterproof membrane, so the deck itself stays close to the temperature of the room below and condensation has nowhere to form. It's now the standard approach on any proper flat roof replacement — and it's also a chance to genuinely improve a room's insulation while the roof's already being redone, rather than just replacing what was there before.

When we replace a flat roof, this is a conversation we actually have with you — not a detail buried in the small print.

Outlets block more than people expect, and Dublin's mature gardens don't help.

Flat roof drainage relies on the outlet — the point water actually leaves the roof — staying clear. Leaves, moss, and general debris build up over a Dublin autumn and winter faster than most people check for it, and a blocked outlet turns a well-built flat roof into a pond overnight. It's a five-minute check that prevents a genuinely expensive problem.