What roof insulation costs in Ireland
Insulating an attic floor costs €1,800 to €2,101 for a semi-detached house and €2,400 to €2,700 for a detached one, before an SEAI grant of €1,500 or €2,000. Insulating a room in the roof at the rafters, with a plasterboard finish, runs €100 to €180 per m², and a warm flat roof with a new membrane €130 to €190 per m². VAT is included.
Every method priced, per home and per m², with the grant taken off where there is one.
Free and no obligation. Your plan goes to one contractor, not a list.
- €1,800–€2,101attic floor, semi-D, before the grant
- €100–€180per m² at the rafters, finished
- €130–€190per m², warm flat roof
- €2,000most SEAI attic grant, detached
Our price guide
VAT included, for work in 2026.
| Job | Cost, VAT included | What moves it |
|---|---|---|
| Attic floor, detached house | €2,400–€2,700 | SEAI grant €2,000, or €2,500 at the higher rate |
| Attic floor, semi-detached or end-of-terrace house | €1,800–€2,101 | SEAI grant €1,500, or €1,900 at the higher rate |
| Attic floor, mid-terrace house | €1,600–€2,200 | SEAI grant €1,400, or €1,800 at the higher rate |
| Attic floor, top-floor apartment | €1,200–€1,515 | SEAI grant €1,100, or €1,400 at the higher rate |
| Attic floor, per m² | €25–€50 per m² | Mineral wool to about 300 mm, between and over the joists |
| Rafter level, boards and plasterboard | €100–€180 per m² | A room in the roof or sloping ceilings, finished and skimmed |
| Spray foam at roof level | €50–€100 per m² | Shown for comparison: see our spray foam page before choosing it |
| Warm flat roof with a new membrane | €130–€190 per m² | Boards on the deck, a vapour control layer and the new covering |
| Vent cards for foam or rafter work | €400–€800 | Keep the 50 mm air gap open under the felt along every rafter |
Attic floor figures are for a whole home, from what SEAI-registered contractors were paid in 2026 and what an Irish installer charges. Per m² figures are installed.
What's included
- Attic floor: lifting stored things off the joists, the wool laid in two layers, eaves vents, lagging the tank and pipes, an insulated draught-stripped hatch
- Rafter level: boards cut between the rafters with an air gap, insulated plasterboard under them, skim
- Warm flat roof: insulation boards, a vapour control layer, the new membrane and its trims
- VAT on the work
What pushes it up or down
- A boarded attic floor, a water tank or downlighters in the ceiling below
- Taking down old plasterboard before a room in the roof is insulated
- Rotten deck boards found when a flat roof is stripped
- Spray foam that has to come off before anything else is done
- The grant: approved before work starts, and paid after the contractor submits the paperwork
Attic insulation, by home and by size
For an attic floor, a semi-D comes to €1,800 to €2,101 before the grant and about €300 to €601 after it. Every kind of home, the higher-rate grant and what each attic size costs per m²: attic insulation cost.
Plan your roof insulation
A few quick taps, and your plan fills in as you answer: the right method for your roof, what it costs, the grant and the standard to ask for. Contact details come last, and only if you want a contractor to price it.
Attic floor insulation, semi-d or end of terrace: €1,800 to €2,101 before the €1,500 SEAI grant, so about €300 to €601 to pay.
How the estimate is worked out
Attic floor insulation uses what SEAI-registered contractors were paid for each kind of home in 2026 and what an Irish installer charges, with the SEAI grant taken off. A room in the roof and a flat roof are priced per m² of the area you enter: rafter boards with a plasterboard finish, or a warm roof with a new membrane. VAT is included. Use it to plan with. It isn't a quote: a contractor prices your roof after a survey.
Rooms in the roof and flat roofs, by size
- A room in the roof of 20 m² (sloping ceilings, knee walls and top ceiling): €2,000 to €3,600, VAT included.
- A room in the roof of 30 m² (sloping ceilings, knee walls and top ceiling): €3,000 to €5,400, VAT included.
- A room in the roof of 40 m² (sloping ceilings, knee walls and top ceiling): €4,000 to €7,200, VAT included.
- A warm flat roof of 15 m² on an extension: €2,000 to €2,900, VAT included.
- A warm flat roof of 25 m² on an extension: €3,300 to €4,800, VAT included.
- A warm flat roof of 40 m² on an extension: €5,200 to €7,600, VAT included.
Measure a room in the roof as the area of sloping ceiling, knee wall and top ceiling together, not just the floor. The planner on this page works out the same sums.
Where the money goes further
- Top up, don't strip. Dry, even insulation already on the joists can stay; the new layer goes across it.
- Do a flat roof when it needs re-covering. The insulation and the new membrane share the scaffold and the labour.
- Insulate over the rafters when you re-slate. With the slates off, the boards go on top and the rooms keep their headroom.
- Apply for the grant first. Work started before approval doesn't qualify.
- Ask for the U-value on the quote. It makes two quotes for different products comparable.
Questions before you insulate
How much does it cost to insulate an attic in Ireland?
€1,800 to €2,101 for a semi-D and €2,400 to €2,700 for a detached house, before the SEAI grant.
How much does rafter insulation cost per m²?
€100 to €180 per m² for rigid boards with an insulated plasterboard finish.
How much does it cost to insulate a flat roof?
€130 to €190 per m² as a warm roof with a new membrane: €3,300 to €4,800 for a 25 m² extension roof.
Do these prices include VAT?
Yes. SEAI's figures are what registered contractors were paid, and the per m² rates are installed prices.
Is spray foam cheaper than boards?
Per m², spray foam at roof level runs €50 to €100, less than finished rafter boards, but it is harder to inspect and remove, and it isn't grant-aided on its own.
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Methods
Costs, grants and rules
Keep the heat under your roof
Pick the roof, what's there now and the home to see the method and the cost. When you want a firm price, your plan goes to a single vetted insulation contractor for your area.