SA RoofingHow much does a flat roof repair cost in Dublin?
Flat roof prices depend more on what is under the felt than on the felt itself. This guide explains what drives the cost of repairing or replacing a flat roof in Dublin and gives broad, hedged ranges for common jobs.
- Patch repair
- Roughly €250 to €600
- New torch-on garage roof
- Roughly €1,800 to €3,500
- Biggest unknown
- The condition of the deck under the old felt
- Price
- Free written quote after a visit
How much does a flat roof repair cost in Dublin?
As a rough guide, patching a split or blister on a Dublin flat roof typically costs €250 to €600, and resealing a failed upstand €300 to €800. A new two-layer torch-on roof costs roughly €1,800 to €3,500 on a single garage and €2,500 to €5,000 on a typical rear extension, with rotten decking adding €30 to €60 per square metre.
As a rough guide only. SA Roofing gives a free written quote after inspecting the roof.
The ranges below are broad market figures for typical Dublin homes with reasonable access. They exclude scaffolding unless stated and can move up or down quite a bit depending on the roof. Use them as a rough guide only.
| Job | Rough Dublin range |
|---|---|
| Patch repair of a split, blister or small damaged area | Roughly €250 to €600 |
| Resealing a failed upstand or flashing where the flat roof meets a wall | Roughly €300 to €800 |
| New two-layer torch-on roof on a single garage, including stripping the old felt | Roughly €1,800 to €3,500 |
| New torch-on roof on a typical rear extension, including stripping the old felt | Roughly €2,500 to €5,000 |
| Replacing rotten decking where needed | Roughly €30 to €60 per square metre on top of the roofing |
| Adding insulation during a replacement | Roughly €40 to €80 per square metre extra |
Flat roof cost per m² in Ireland
Flat roofs are often priced by the square metre, and that is a useful way to compare quotes, but it works less well on small domestic roofs than on large ones. A rate per square metre covers the membrane and the labour to lay it, while the set-up, access, stripping the old roof, edge trims and upstands cost much the same whether the roof is 8 or 30 square metres. That is why a porch or a small garage roof usually works out dearer per square metre than a large extension.
When a quote does give a rate per square metre, check what it includes. The extras most often priced that way are replacing rotten decking and adding insulation, and the table above gives rough ranges for both, on top of the roofing itself. For the whole roof, the job prices in the table are a more reliable guide than a single rate, and we give a free written quote after measuring and inspecting the roof.
Not sure what yours needs? WhatsApp us a photo and we will tell you what it looks like.
WhatsApp a photoOr get a free quoteGarage, porch and dormer flat roof costs
A single garage is one of the smaller flat roof jobs, and the table above gives a rough range for a new two-layer torch-on roof on one. Porches are smaller again, but they rarely cost proportionally less, because a porch roof usually has an upstand against the front wall, a drip edge over the door and awkward access over a path or a bay, and the set-up time is the same as on a bigger roof.
Dormer roofs are small in area but sit high up, so scaffolding is often the largest single cost, and the cheeks and flashings on either side are usually checked during the same visit. On all three, the condition of the deck is what moves the price most once the old felt is off. Our guide to a leaking dormer roof explains where dormers usually let water in.
Why flat roof prices vary so much
Flat roofs cover a huge number of Dublin extensions, garages, dormers and porches, and they range from a few square metres over a front door to a large roof over a kitchen and living area. Two roofs that look the same from the garden can be very different jobs. One may need a single split cut out and patched, while the other has a deck that has been soaking up water for years and has to be stripped back to the joists.
The figures in this guide are broad market ranges for Dublin, given as a rough guide for budgeting. They are not SA Roofing's prices, and every roof we work on is priced individually after an inspection.
What drives the cost of flat roof work
Size of the roof
Larger roofs need more membrane, more labour and more time, although the price per square metre usually falls as the area grows because the set-up time is shared across more roof. Very small roofs, such as porches, can cost more per square metre for the same reason.
Condition of the deck
This is the biggest unknown. Torch-on felt has to be laid on a deck that is sound and dry, so if the timber boards beneath the old covering are wet or rotten, they have to be replaced first. That is often only visible once the old felt has been stripped. Chipboard decks in particular lose their strength quickly once they get wet.
Upstands, outlets and edge details
Every place where the flat roof meets a wall, a rooflight, a soil pipe or a gutter needs its own detail. A plain garage roof with a single edge draining to the gutter is a simpler job than an extension roof with two walls to seal against, a rooflight in the middle and an internal outlet.
Access and height
A single-storey extension can usually be reached from ladders or a small tower. A dormer, or a flat roof at second floor level, may need scaffolding, which adds to the cost and has to be arranged in advance.
Insulation and falls
When a roof is being replaced, it is a good time to add insulation or correct falls that cause ponding. Both add to the price, but they are far cheaper to do while the roof is open than at a later date. Insulation has to be designed properly to avoid condensation inside the roof.
Removing the old roof
Stripping old felt, chippings and sometimes several layers of earlier repairs takes time, and the waste has to be taken away. The more layers there are, the longer the strip takes.
How the repair or replace decision changes the cost
A patch is always cheaper on the day, and for a roof that is otherwise sound it is the sensible choice. The picture changes when a roof has already been patched several times, the felt is brittle across large areas, or more than one part of the deck is soft. Each repair then buys less time, and the money spent on patches would have gone a long way towards a new roof.
Our article on flat roof repair vs replacement goes through the signs that point one way or the other. Either way, the condition of the deck is what usually decides it, which is why a roofer needs to look at the roof before giving a price.
How to keep flat roof costs down
Keep outlets and gutters clear, since a blocked outlet causes ponding and standing water shortens the life of the membrane. Look at the roof after storms for lifted edges or splits, and deal with small leaks before they soak the deck, because wet decking is what turns a cheap patch into a replacement. Avoid walking on the roof or leaning ladders against the edge trims.
When a replacement is due, ask for the falls to be checked and corrected, because a roof that drains properly lasts much longer. If the gutters are part of the problem, a gutter clean clears the outlets and downpipes that a flat roof drains into.
Getting an accurate quote
When comparing quotes, check that each one covers the same work: removal of the old covering, the number of layers in the new system, upstands and edge trims, any allowance for decking, insulation and access. Ask how rotten decking found during the strip would be priced, so there are no surprises halfway through the job.
SA Roofing repairs, installs and replaces felt and torch-on flat roofs across Dublin. See our flat roof repairs page, or our roof repairs page for the pitched roof above. Because the deck decides so much of the price, we look at the roof and the ceiling below it before giving you a free written quote, and photos sent on WhatsApp beforehand help us judge how urgent the job is.
Frequently asked questions
Why can a flat roof price change after the old felt is removed?
The condition of the deck underneath can only be seen once the old covering is off. If boards are rotten they have to be replaced before the new roof goes on. A good roofer will explain in advance how that would be priced and show you any damage before carrying out extra work.
Is torch-on more expensive than ordinary felt?
A two-layer torch-on system usually costs more than a single layer of older-style felt, but it lasts much longer and is the standard choice for flat roofs in Ireland today. Over the life of the roof it is usually the better value.
Does a flat roof repair need scaffolding?
Most single-storey extension, porch and garage roofs can be reached from ladders or a mobile tower. Dormers and higher flat roofs may need scaffolding, which should be shown separately in the quote.
Can I get a flat roof price from photos?
Photos help a roofer judge how urgent a problem is, but they cannot show the condition of the deck or the details at the upstands. An inspection is the only way to give an accurate price.
Is it worth adding insulation when the flat roof is replaced?
Often, yes, particularly over a heated room such as a kitchen extension. It adds to the cost of the job, but doing it while the roof is open is far cheaper than doing it later. It needs to be designed properly to avoid condensation.
How much does a garage roof replacement cost?
A single garage is one of the smaller flat roof jobs, so it usually sits at the lower end of the replacement range in the table above. The condition of the deck and the access make most of the difference, and we give a free written quote after seeing it.