Rafters and roofs
Roof insulation grant: rafters, rooms in the roof, flat roofs
For the grant, SEAI wants every heat-loss part of the roof insulated: the attic floor, sloping rafters over rooms, rooms in the roof and flat roof extensions. Only hard-to-reach areas making up 15% or less of the heat-loss roof can be left out. Rafters must reach a U-value of 0.20, ceilings 0.16.
This catches people out: the grant is for the whole roof, not just the easy part of the attic.
Free, no obligation. One SEAI-registered contractor prices it, not five.
- €2,000SEAI attic grant for a detached house
- €2,500at the higher rate
- €300 to €600typically left to pay on a semi-D
- 300 mmof wool: what SEAI's standard takes
The whole-roof rule
Every heat-loss roof counts
SEAI's April 2025 bulletin to contractors says a whole-surface solution means insulating every roof element with heat loss to the outside or to unheated space, "including (but not limited to) extensions, flat roofs, room-in-roofs". It adds that being economically feasible has nothing to do with whether you can afford your share: it's about how hard an area is to reach.
The 85% exception
What can be left out
| Share of the heat-loss roof insulated | What happens |
|---|---|
| 100% | Nothing more needed |
| 85% to 99% | The contractor records the areas left out, in m², and why |
| Under 85% | More work needed before the grant can be paid |
From SEAI's roof insulation bulletin. The target U-value still has to be met.
Rafters
Insulating between the rafters
Where insulation goes on the slope, SEAI's standard sets a U-value of 0.20 W/m²K and a ventilation gap: 50 mm of clear air above the insulation, with vents equal to a 25 mm strip at the eaves and 5 mm at the ridge. If the roof has poor ventilation, the contractor has to tell you in writing. Where part of an attic is converted and part isn't, the unused part is insulated at ceiling level to 0.16.
How common
How Irish houses are insulated in the roof
Predominant roof type on each certificate; houses built before 2011, grant BERs left out, our sums. Rafter insulation is most common in Kerry, Wicklow, Clare.
Converted attics
If your attic is a room
A room in the roof is insulated in its walls, sloping ceiling and the small attic spaces behind the walls. It costs more than a plain attic, but SEAI expects it done if it's part of the heat-loss roof. The free Warmer Homes Scheme won't insulate a converted attic.
Grant check
Your attic grant and what's left to pay
Two taps: your home, and which rate fits you. The answer is SEAI's fixed grant and its own median cost for the job.
Your SEAI attic insulation grant
€1,500
- SEAI median cost, Jan to Jun 2026
- €2,101
- Left to pay at the median
- €601
SEAI's fixed grant for a semi-d or end of terrace at the standard rate is €1,500. SEAI's median cost for attic insulation on a semi-d or end of terrace from January to June 2026 was €2,101. €2,101 less €1,500 leaves about €601. Our sum; your quote can be higher or lower.
Send this for a real priceHow this is worked out
The grant is SEAI's fixed amount for that home type and rate, as Citizens Information lists it. The median cost is SEAI's own figure from grant-funded attic jobs completed between January and June 2026; the PDF doesn't say whether VAT is in. Left to pay is the median less the grant, our sum. The home must have been built and lived in before 2011, the contractor must be on SEAI's register, and SEAI must approve the grant before work starts. It's an estimate, never a quote.
Your grant
Your attic grant and a price, in 4 taps
Tap your home, when it was built, what's in the attic now and who you are. Then leave your number and one SEAI-registered insulation contractor who covers your area rings you to look at the attic and price it in writing.
FAQ
Questions people ask
Does the SEAI grant cover rafter insulation?
Yes, as part of the roof. SEAI's standard covers rafter insulation to a U-value of 0.20 W/m²K, and expects every heat-loss roof area done.
Do I have to insulate my flat roof extension too?
SEAI's bulletin includes flat roof extensions in the whole-surface rule. Only areas of 15% or less of the heat-loss roof that are hard to reach can be left out.
What U-value does a roof need for the grant?
0.16 W/m²K at ceiling level and 0.20 W/m²K at the rafters.
Is the grant higher for a room in the roof?
No. The fixed attic grant is the same; the job usually costs more.
Keep reading
Related guides
- Attic insulation costSEAI's median cost by home type, before and after the grant.
- How thick should attic insulation be?300 mm, 200 mm, blown wool or boards: what reaches SEAI's standard.
- Spray foam attic insulationVentilation, timbers, resale: read this before anyone sprays your roof.
- Attic insulation grant amounts 2026Every attic grant rate in one table, and what changed in 2026 by date.