By Patrick Foley, Business Owner
*What it is, how long it lasts, and when a Cork homeowner should repair, overlay or replace*
Torch-on felt is a bitumen membrane roofing system, applied in two or three layers with a gas torch, and it's the most common flat-roof covering on Cork extensions, dormers and garages built between roughly 1985 and 2010. A well-laid torch-on roof lasts 15–20 years in Cork's climate; failure typically starts with cracked bitumen, ponding water or a slow leak into the ceiling below.
Summary
- Torch-on (also called "built-up felt") is a two- or three-layer bitumen membrane heat-welded on site with a propane torch — different animal to pour-and-roll felt from the 1970s.
- Expected life in Cork conditions is 15–20 years; on a north-facing dormer in Ballintemple or Bishopstown, expect the lower end.
- Indicative installed rate for traditional felt is €50–€70/m², but we no longer recommend it for new work — EPDM at €80–€100/m² and single-ply PVC at €90–€120/m² outlast it and cost less over the roof's life.
- Small localised repairs (a split seam, one blister, a lifted upstand) can be patched; if you see multiple blisters, ponding, or the felt is brittle underfoot, the deck usually needs looking at and a full recover is the honest call.
- Deck replacement where the OSB or plywood underneath has gone soft adds €30–€50/m² on top of the membrane rate.
- Urgent: any active drip through a ceiling after wind-driven rain off the harbour, or visible sag in a flat roof, is a same-day job — water sitting on a compromised deck accelerates rot every hour.
What torch-on felt actually is
"Torch-on" describes the installation method, not the material. A roofer rolls out a polyester- or glass-reinforced bitumen membrane, heats the underside with a propane torch until the bitumen melts, and beds it to the deck below. A cap sheet — usually mineral-finished, in slate grey or green — goes on top and is welded to the underlay at the seams.
Done properly, you get a monolithic waterproof layer with no mechanical fixings piercing the surface. Done badly — under-torched seams, cold laps, a torch held too long in one spot and scorching the membrane — you get failures within five to eight years. Cork has both.
The system replaced the older "pour-and-roll" felt from the 1960s and 70s (three layers of felt bonded with hot bitumen from a bucket), and it was the default flat-roof spec on Irish extensions from the mid-80s until EPDM rubber started taking over in the early 2010s. If your house has a flat-roof kitchen extension, a garage, a dormer cheek, or a porch canopy built in that window, torch-on felt is what's up there roughly nine times out of ten.
How to tell if you have torch-on felt
From the ground, look for a grey or green mineral-finished surface with grit that comes off in your hand if you rub it. You'll see rolls butted along their long edges, usually about a metre wide, with the seams running down the fall of the roof. Upstands against walls are typically 150mm high and finished with a lead or aluminium counter-flashing chased into the mortar.
If the surface is smooth and rubbery with no seams visible — that's EPDM. If it looks like painted fibreglass with a slight sparkle — that's GRP. If it's silver and asphalt-like with a bitumen smell in summer — that's the older mastic asphalt, common on 1930s and 40s Cork houses in Sunday's Well and Montenotte.
The signs your torch-on roof is failing
The five things worth checking every autumn, before Cork's storm season sets in:
- Cracks and crazing on the cap sheet. UV breaks down the bitumen binder over time. Fine cracking is cosmetic; deep cracks that expose the reinforcement are water pathways.
- Blisters. Air or moisture trapped between layers expands in summer heat. One or two isolated blisters can be cut, dried and patched. A field of them means the bond has failed across the roof.
- Ponding water 48 hours after rain. Cork gets roughly 1,200mm of rainfall a year, most of it in short heavy bursts off the Atlantic. A properly falled roof drains within a day. Standing water indicates deck sag or an original fall that was never right.
- Lifted or open seams, especially at upstands and around soil vents. These are the first places to fail because the roofer has to work the torch into an awkward angle.
- A stain on the ceiling below, or a musty smell in the room under the flat roof. By the time water shows internally, the deck has usually been wet for weeks.
Homes closer to the coast — Blackrock, Ballintemple, and out to Cobh and Kinsale — get the extra kicking of salt-laden wind and horizontal rain, which finds the smallest lifted seam and drives water under the membrane.
Repair, overlay, or full replacement
The honest test is the same as it is for Cork roof repairs generally: fix what's localised, replace what's failing along its length.
Repair makes sense when the membrane is broadly sound (under about 12 years old, no widespread crazing) and the fault is a single split, a lifted seam, or a damaged upstand. A competent patch — cutting back to sound material, priming the deck, and heat-welding a new section — buys you the rest of the roof's design life.
Overlay — welding a new cap sheet over the existing membrane — is a middle option some Cork roofers offer at around 15 years in. It works if the existing surface is flat, dry and firmly bonded, and it saves the strip-out cost. It doesn't work if the deck is soft, if there's trapped moisture (you'll blister the new layer within a season), or if the falls are already wrong. We'll say so on the survey.
Full replacement is the right call when the membrane is at end of life, when multiple failure signs are present, or when the deck itself has gone. At that point, we'd steer most Cork homeowners away from felt entirely and toward EPDM or single-ply PVC — 25–35 year systems for a small premium on the installed rate, with fewer seams and no torching risk near timber structures.
What it costs in Cork
Every figure below is indicative and confirmed free after a site survey.
| System | Installed rate | Expected life |
|---|---|---|
| Traditional torch-on felt | €50–€70/m² | 15–20 years |
| EPDM rubber membrane | €80–€100/m² | 25–35 years |
| Single-ply PVC | €90–€120/m² | 25–35 years |
Deck replacement where the plywood or OSB under the membrane has deteriorated adds €30–€50/m². On the majority of failed torch-on roofs we survey, at least a portion of the deck needs replacing — moisture wicks under lifted seams and rots the timber from above.
Typical project cost by size:
| Roof | Size | Indicative cost |
|---|---|---|
| Small extension or garage | 15–25 m² | €1,200–€3,500 |
| Larger extension or dormer set | 50–100 m² | €4,000–€12,000 |
What moves the price within those ranges: access (a first-floor dormer needs scaffolding), the number of upstands, penetrations for soil vents and rooflights, whether existing gutters and outlets are being renewed, and how much of the deck needs replacing. Confirm exact rates after a survey.
Why we no longer recommend torch-on for new work
Three reasons, all honest ones.
First, lifespan per euro. EPDM at €90/m² lasting 30 years works out cheaper per year than felt at €60/m² lasting 18 — before you factor in the second replacement you'll pay for on the felt.
Second, fire risk. Torching bitumen next to timber fascias, uPVC soffits and roof insulation is how flat-roof fires start. The Irish trade has moved decisively away from open flame near residential timber, and rightly so.
Third, seams. Felt has a seam every metre. EPDM on a domestic extension often has none — the sheet is cut to size and dressed as one piece. Fewer seams, fewer future failures.
We still repair torch-on felt every week across Cork, and we'll overlay a sound roof where that's the sensible answer. We just won't specify new felt on a job where the owner has a choice.
When it's urgent
Call the same day if you see:
- Active dripping through a ceiling below a flat roof, especially after wind-driven rain.
- A visible sag or dip in the roof surface — the deck is likely saturated.
- Membrane physically lifted or flapping after a storm (common in Cork after the winter southerlies coming up the harbour).
- Water coming down an internal wall from the junction between a flat roof and the main house — usually a failed upstand or counter-flashing.
We provide same-day make-safe and 24/7 emergency call-outs across the city and county. The call-out stops the water and makes the property safe; the permanent repair is quoted separately once we can properly assess the deck. Every emergency job is documented with timestamped photographs — useful if you end up making an insurance claim under the storm peril.
Cork-specific notes on flat roofs
Cork's housing stock produces a fairly predictable pattern of flat-roof work. City-centre and inner-suburb Victorian and Edwardian properties in Ballintemple, Blackrock and Sunday's Well often have small flat roofs over bay-window projections and rear returns — usually felt over a timber deck, often on the third or fourth covering by now. Blackpool and Bishopstown have a lot of 1970s and 80s semis with flat-roof kitchen extensions coming to the end of their second felt life. Coastal villages like Ardmore and out toward Bantry get the worst of the wind exposure — seams fail earlier and the counter-flashings work loose in the salt air.
Blocked outlets and hoppers are a recurring cause of "leak" calls that turn out to be overflow. If your flat roof drains into a hopper and downpipe, a gutter clean at the same time as the roof survey is worth doing — water sitting on felt because the outlet is blocked with moss is a preventable failure.
Guarantees and how the job runs
A repair to a torch-on roof carries a written workmanship guarantee of at least 3 years, rising to 10 years on major repair work. A full replacement — whether we recover in felt (rarely), EPDM or single-ply — carries a 10-year replacement guarantee with the manufacturer's material warranty on top. All in writing, on the quote, before any work starts.
The job itself: free on-site survey, written quote with the range explained, no deposit on anything under €10,000 (a 33% deposit applies at or above that), and payment on completion. We're fully insured with €6.5m public liability, VAT registered (IE4415315DH), and company-registered (782157) — the kind of thing that matters if the work ever ends up in an insurance claim.
If you'd like an honest look at a flat roof anywhere in the city or county, get a free quote from our Cork team and we'll tell you plainly whether it's a patch, an overlay or a full recover. Call 021 7020328.
Frequently asked questions
How long does torch-on felt last in Ireland? 15–20 years is the realistic range in Cork's climate. South-facing roofs get more UV and tend to craze earlier; north-facing roofs stay damp longer and can suffer from moss and biological growth. A well-installed roof kept clear of debris will make the upper end; a poorly torched one with ponding water can fail in under 10.
Can torch-on felt be repaired, or does it all have to come off? Localised repairs work well on a membrane that's broadly sound. A single split, a lifted seam or a damaged upstand can be cut back, primed and heat-welded — expect a small repair to run in the low hundreds. Once you're seeing multiple blisters, widespread crazing, or ponding across the roof, you're paying good money to patch a system that's at end of life.
Is EPDM really better than felt, or is that just what roofers upsell now? Both statements are partly true. EPDM genuinely does last longer (25–35 years vs 15–20), has fewer seams on a domestic-scale roof, and involves no open flame. It's also a better margin for the roofer. Our position: if the roof is going to be there for 25+ years and it's your family home, EPDM or single-ply pays back. On a garage you plan to knock in 8 years, a felt overlay is fine.
Will my insurance cover a leaking flat roof? Storm damage — a membrane physically lifted or torn by high winds — is usually covered under the storm peril. General wear and tear, ponding, and gradual failure over years typically aren't. Cork insurers vary on how they treat "storm plus age": a 25-year-old felt roof that lifts in a gale is often argued as end-of-life rather than storm damage. We provide timestamped photographic evidence and cost estimates in the format loss adjusters expect.
Do you handle the fascias and gutters at the same time as a flat-roof recover? Yes, and it usually makes sense to. If we're already on scaffolding and the fascia behind the flat roof is soft or the gutter outlets are corroded, doing it together saves you a second mobilisation. See our fascia, soffit and guttering work for what's involved.
How quickly can you get out to a leaking flat roof in Cork? Same day for emergencies — a leak actively coming through a ceiling gets a make-safe visit within hours. Non-urgent surveys are usually within the week across Cork city and county.