A flat roof in Ireland costs €55 to €130 per square metre fitted for the common systems. That works out around €2,000 to €4,500 for a single garage and €3,500 to €6,500 for a rear extension. Insulated warm roofs and zinc run higher.

HP Roofing has been laying flat roofs on Dublin and Leinster buildings since 1969. Directly employed crews, fully insured, and a written fixed quote before any work starts.

What A Flat Roof Costs In Ireland On Average

Most domestic flat roof replacements land between €55 and €130 per square metre fitted. That covers stripping the old covering, the new membrane, trims, outlets and waste disposal. Where the roof sits over a heated room and needs insulation added, the rate moves higher.

Flat roof pricing works differently to pitched roofing in one important way. The rate per square metre is a poor guide on small roofs. A porch roof and a garage roof both need a setup, a strip, edge trims, an outlet and a day of labour, so the small one costs far more per square metre than the arithmetic suggests.

Measuring is straightforward. A flat roof area is close to its footprint, so length by width gives you a usable figure without climbing anything. A single garage is usually 18 to 25 square metres. A rear kitchen extension is commonly 30 to 40.

Those figures assume normal access and a sound deck. Zinc on a modern extension sits above all of them and is priced from a survey.

For a ballpark before you book anything, our roof cost calculator gives an instant estimate from your size and material.

Flat Roof Cost Per Square Metre By System

The covering decides the price and how long the roof lasts. Cheaper systems cost less now and come back around sooner. The ranges below are fitted rates excluding scaffolding.

Felt is the cheapest way to cover a flat roof and the shortest lived. EPDM and fibreglass are the two most common choices on Irish extensions and garages, and both should give you twenty five years or more where the deck is sound and the detailing is right.

The ranges are wide because flat roofing is detail work. Two roofs of the same area can differ by thousands once you allow for an upstand into an existing wall, a rooflight kerb, a parapet or an awkward outlet.

The systems used on larger domestic and commercial roofs are quoted differently. Single ply PVC, Trocal and mastic asphalt are specified by build-up rather than by a simple rate, so they come off a survey. Our torch-on felt, fibreglass and zinc roofing pages set out where each system earns its place.

What A Flat Roof Price Should Include

A flat roof quote should itemise the build-up rather than name a material and a number. If the quote is a single line, that is your first question to ask.

A complete flat roof price should account for the following.

• Stripping and disposal of the old covering, including skip hire
• Deck inspection and replacement of any soft or rotten boards
• Firrings or tapered insulation to create a fall so water runs off the roof
• The waterproof covering itself, whether felt, EPDM, fibreglass, single ply or zinc
• Edge trims, upstands and flashings where the roof meets a wall, a parapet or a chimney
• Outlets and the connection into your gutter or downpipe
• Insulation where the roof sits over a heated room
• Labour, supervision and site clean-up

Two of those catch people out. The deck cannot be assessed until the old covering is off, and the fall is invisible from the ground. If your current roof holds water for days after rain, the fall is wrong, and a new covering laid on the same fall will pond in the same place.

Ask one more question in writing. Is this a strip or an overlay. Laying a new covering over a failed one costs less on the day and hides wet timber underneath.

What Pushes A Flat Roof Quote Up Or Down

Beyond the covering, a handful of factors decide where your quote lands inside these ranges.

• Size and shape. Larger roofs cost more overall and less per square metre. Small roofs carry the same setup over fewer metres.
• Deck condition. Soft or rotten boards have to come out before anything goes down. Replacing the deck commonly adds around €20 to €30 per square metre.
• Insulation. A warm roof build-up costs more than a straight recover, and it is usually the right call over a heated room.
• Access. A garage roof at ground level often needs edge protection rather than a full scaffold. A flat roof at first floor level or behind a terrace usually needs a scaffold, commonly €800 to €1,500.
• Detailing. Rooflights, parapets, upstands into an existing wall and tie-ins to a pitched roof all add specialist time.
• Location. Dublin and the commuter counties typically run 10 to 20 per cent above rural labour rates, before parking restrictions and skip permits.

Then there are the jobs worth doing while the roof is open and the access is already paid for. A new skylight, a box gutter repair or a new outlet costs less now than calling a roofer back next year.

The Costs That Catch People Out

The headline number covers the covering, the trims and the standard outlet detail. Several extras appear regularly, and knowing them in advance stops a mid-job phone call turning into an argument.

• Rotten decking. Nobody can price this before the old covering comes off. Budget a contingency rather than assuming the best.
• Fixing the fall. If water ponds, the answer is tapered insulation or new firrings. That is a change to the build-up, not a patch.
• Leadwork and upstands. Where the flat roof meets a wall, a parapet or a chimney, the flashing usually needs renewing at the same time.
• Waste and skip hire. Old felt and wet boards are heavy. Disposal should appear as its own line rather than disappearing into the total.
• Older cold decks frequently lack the airflow they need, which shows up as condensation that looks exactly like a leak.

It is also worth asking whether you need a full recover at all. If the deck is sound and the problem is one outlet or one split, a targeted flat roof repair can cost a fraction of a replacement, and our roof repair cost guide breaks the smaller jobs down further.

Cold Roof Or Warm Roof And Why It Changes The Price

This is the biggest decision on any flat roof over a heated room, and it is the one most quotes leave vague.

A cold roof carries the insulation between the joists, underneath the deck. A warm roof carries it above the deck with the covering laid on top, so the structure sits on the warm side and stays dry.

Warm roofs cost more. Expect €110 to €190 per square metre for a full warm roof build-up against €80 to €130 for a straight recover on a sound deck. Where a deck is already sound, adding insulation to it typically lifts the rate by around €25 to €50 per square metre.

Over a garage or a shed, a cold deck is usually fine. Over a kitchen, a bedroom, a bathroom or a converted garage, a warm roof is normally the better build. Roofs in new work are generally specified to a U-value of 0.16 W/m²K, and a flat roof replacement is the natural moment to move towards that.

Whether the building regulations formally require an upgrade depends on the scope of the works, so ask your contractor or a BER assessor to confirm before the job is scoped. Our warm roof construction and roof insulation pages explain how the two build-ups differ.

Repair Or Replace A Flat Roof

Flat roofs get patched more often than any other roof, and patching one that has reached the end of its life costs more over five years than recovering it once.

Repair usually makes sense when the leak is isolated around one outlet, one trim or one upstand, the covering is under ten years old, and the deck underneath is dry.

Replacement usually makes sense when there are several leaks, the membrane is blistering or lifting at the seams, water is ponding for days after rain, the deck feels soft underfoot, or you have already paid for two or more repairs in the last few years.

The practical test is proportion. Once a repair quote approaches a quarter of the cost of a recover on an ageing roof, replacement is the better value. A localised flat roof repair typically runs €250 to €900. Our repair versus replace guide walks through the decision, and our guide to how long a roof lasts covers what shortens those figures.

VAT And Grants On Flat Roofing Work

Flat roofing work carries VAT, and for most homeowners it is the reduced rate rather than the standard one. Direct grants for roof coverings do not exist, and the grant position on flat roof insulation is narrower than most guides suggest.

How VAT Applies To Flat Roofing Work

Roofing is a construction service, and the renovation or repair of a private dwelling generally attracts the reduced 13.5 per cent VAT rate rather than the 23 per cent standard rate.

One rule is worth knowing. If the materials in a job cost more than two thirds of the total price excluding VAT, the whole job moves to 23 per cent. That is Revenue’s two thirds rule. On a labour heavy flat roof it rarely bites, but on a supply heavy job it can.

Scaffolding hire is commonly billed at the standard rate even inside a qualifying job, so check how it appears on your quote. Ask for a VAT inclusive written price so there are no surprises at the end.

Grants That Can Reduce Your Flat Roofing Bill

There is no SEAI grant for replacing a flat roof covering, and there is no individual SEAI grant for flat roof insulation either. The individual insulation grants cover attic insulation and wall insulation.

The attic insulation grant is worth €2,000 for a detached house, €1,500 for a semi-detached or end of terrace, €1,400 for a mid terrace and €1,100 for an apartment, with higher fixed amounts for first time buyers and for homeowners on qualifying welfare payments. The home needs an MPRN and must have been built and occupied before 2011, you need grant approval before work starts, the work has to be carried out by an SEAI registered contractor, and a post works BER is required.

Where flat roof insulation forms part of a wider home upgrade, the route is a One Stop Shop whole-house upgrade rather than an individual grant. Check the position with SEAI before you commit to a specification, and see our roof insulation cost guide for what the insulation itself adds.

How To Get An Accurate Flat Roof Quote

The only way to know your real cost is a roof survey followed by a written, itemised quote. Ranges and calculators are for budgeting. A proper quote reflects your measurements, your deck condition and the build-up you choose.

1. Get at least three written itemised quotes so you compare specification rather than the bottom line.
2. Have the system named. Torch-on felt, EPDM, fibreglass, single ply and zinc are different jobs at different prices.
3. Ask whether the deck is being replaced, and what happens to the price if boards are found soft once the roof is open.
4. Ask what the fall is and how the roof drains, especially if the current roof holds water after rain.
5. Get both guarantees in writing, the manufacturer warranty on the material and the workmanship guarantee on the installation.

HP Roofing has been laying flat roofs in Dublin since 1969, for homeowners and for buildings including Trinity College Dublin and The Shelbourne. Crews are directly employed rather than subcontracted, the company is a member of the National Guild of Master Craftsmen, and every quote is written and fixed before work starts. Our guide to choosing a roofing contractor covers what else to ask, and the flat roofing page sets out how we scope and price a replacement.