Roofing

Flat roofing

Felt, EPDM or fibreglass on an extension, garage or dormer.

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Whether this needs a licence in Ireland

Ireland

No licence required

Taken from the statute below; not yet reviewed by a lawyer

Irelandwww.cru.ieChecked 14/10/2026

Flat roofing: what the job involves

Re-covering or repairing a flat roof on an extension, garage, porch or dormer in EPDM rubber, GRP fibreglass or torch-on felt. Most flat-roof leaks come from the edges, outlets and where the roof meets a wall, so the detailing matters as much as the membrane.

Also asked for as: flat roof repair · EPDM roof · rubber roof · fibreglass roof · GRP roof

How the job is usually done

Inspect the roof and the ceiling below: find the leak, check for ponding water, and probe the deck for soft spots.
Agree the system — EPDM, GRP or torch-on felt — and whether insulation is being added (a warm roof).
Strip the old covering and any rotten decking, and check the joists.
Lay new OSB or plywood decking with a fall towards the outlet or gutter, and insulation boards if it is becoming a warm roof.
Lay the membrane, form the upstands against walls and dress them under a flashing or chased into the wall.
Fit new edge trims, drip details and outlets, and connect to the gutter or downpipe.
Water-test the outlets and leave the roof clean.

Flat roofing: what is included

Usually included

Stripping the old covering
The new membrane with upstands, edge trims and outlets
Replacing a small amount of soft decking
Taking away the old covering and offcuts

Usually not included — agree it separately

Insulating to a warm-roof specification, unless quoted
New joists or structural repairs
Ceiling repairs and decoration inside
Replacing roof lights or lanterns in the flat roof
Removing asbestos-cement sheeting on old garages

Materials and who supplies them

EPDM rubber membrane, GRP resin and matting, or a torch-on felt system — supplied by the roofer
OSB3 or plywood decking, and PIR insulation boards for a warm roof
Vapour control layer, edge trims, outlets and adhesives
Lead or a proprietary flashing where the roof meets a wall

How long it takes

One to three days for a typical garage or extension roof; rotten decking, adding insulation and a dry-weather window can stretch it.

When to book

Flat roofs need dry weather and, for GRP and adhesives, temperatures above about five degrees, so late spring to early autumn is easiest.

Flat roofing: the rules in Ireland

What the official sources say, checked against them on the date shown. A summary, not legal advice — follow the link to read the rule itself.

Roof work must be planned so nobody can fall from the edge or through the roof: scaffolding or edge protection, roof ladders, and covers or nets over fragile sheets and roof lights. The HSA code of practice sets out what that means in practice.
Applies to: the roofer, as employer or self-employed contractor
Health and Safety Authority — Code of Practice for Safety in Roofwork; Safety, Health and Welfare at Work (General Application) Regulations 2007, Part 4 (work at height) · hsa.ie · Checked 9 October 2026
Where a flat roof is insulated as part of a material alteration, the insulation should meet the U-values for material alterations in Technical Guidance Document L, Table 5. Ventilation and condensation control must be designed in, especially for a cold roof.
Applies to: the roofer or designer
Building Regulations Part L — Technical Guidance Document L, Dwellings (2019), section 2.1.2 and Table 5 · gov.ie · Checked 9 October 2026
Old slates, felt, timber and gutters must go to an authorised facility in a vehicle covered by a waste collection permit. Ask for the permit number if the roofer is taking the waste away.
Applies to: the roofer, and the homeowner who hands the waste over
Waste Management (Collection Permit) Regulations — National Waste Collection Permit Office · nwcpo.ie · Checked 9 October 2026

What flat roofing costs, and why

What jobs on Talqero came to

Not enough comparable jobs yet to publish a range here. Talqero shows a price range only once at least five comparable jobs, agreed prices or offers exist — a range from fewer would describe a handful of jobs, not the market. Post your job and compare the offers you get.

What affects the price

Area of the roof and how many upstands, outlets and roof lights it has
The system: EPDM, GRP or torch-on felt, and its guarantee
Rotten decking or joists found once the old covering is off
Adding insulation to make a warm roof, which raises the roof level and edge details
Access, and whether materials have to be carried through the house
VAT: building work on a home is charged at the reduced 13.5% rate by a VAT-registered roofer, unless materials are more than two-thirds of the price (Revenue’s two-thirds rule)
VAT: building work on a home is charged at the reduced rate of 13.5% by a VAT-registered business — unless the materials come to more than two-thirds of the price, when Revenue’s two-thirds rule applies the goods rate to the whole job. Ask whether a quote includes VAT.

Paperwork to ask for at the end

The membrane manufacturer’s guarantee, registered where the system offers one
The roofer’s written workmanship guarantee
Photographs of the deck and upstands before the membrane went on

Safety

Flat roofs feel safe but have unprotected edges: nobody should walk on one without edge protection.
Torch-on felt uses open flames — ask how the roofer manages fire risk near fascia, eaves and timber.
Older garage roofs of corrugated sheets may be asbestos cement and fragile; do not stand on them.
Resin and adhesives give off fumes: keep windows below closed while GRP cures.

Flat roofing: before you hire

Questions to ask a tradesperson

Which system are you using, and what is the manufacturer’s guarantee?
Will you add insulation, and how will that change the edges and the wall flashing?
What happens if the decking is rotten — is there a rate per board?
Is VAT included?

What you can do yourself

Keeping outlets and gutters clear of leaves is a safe homeowner job from a ladder; membrane work is not.

What to put in your task

What is the flat roof on?
Roughly how big is it?
What is it covered with now?
Is it leaking now?
Are there roof lights or a lantern in it?

Photos that help

The whole flat roof from above, from an upstairs window if possible
Where it meets the house wall and the edges with the gutter
Any ponding water, blisters or splits
The ceiling stain below, if it is leaking

Roofing

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Questions about flat roofing

Does flat roofing need a licence in Ireland?

No licence is required for this work in Ireland (source: www.cru.ie). Ask instead for references and photographs of similar jobs.

EPDM, GRP or felt — which is best?

All three last well when laid properly. EPDM is a single sheet of rubber with few joints and suits simple roofs; GRP is seamless and hard-wearing and suits roofs with foot traffic; modern torch-on felt is a multi-layer system that is easy to repair. The roofer’s experience with the system matters more than the label.

Why does my flat roof hold puddles?

A flat roof should have a fall of at least a little towards the outlet. Puddles that sit for days mean the deck has sagged or was laid level, and they shorten the life of any covering. Re-roofing is the chance to correct the falls with firrings or tapered insulation.

Can a new covering go over the old one?

Sometimes, if the deck underneath is sound and dry. Overlaying a wet deck traps the moisture and rots it, so most roofers strip and inspect first. Ask why they recommend one or the other.

Often booked with flat roofing

Roofers