Spray foam insulation is applied as a liquid that expands and sets against roofs and ceilings. The headline you need first: SEAI does not grant spray foam, and it can create real problems when you come to sell or remortgage. For most Irish homes, a grant-eligible alternative is the safer choice.
What is spray foam?
Spray foam comes in two types:
- Open-cell foam — softer, more breathable, lower insulating value per millimetre
- Closed-cell foam — denser, rigid, higher insulating value, and largely impermeable to moisture and air
It is most often sprayed onto the underside of a roof (between and over the rafters) to create a “warm roof”, or onto attic ceilings. The selling point is a continuous, gap-free, draught-sealing layer. The problems lie in what that layer does to the roof structure and to future surveys.
Why SEAI does not grant it
Spray foam is not on the list of SEAI-supported insulation measures. There is no spray foam grant — none of the dwelling-type grant amounts that apply to attic or wall insulation are available for it. That alone makes it poor value next to measures that attract funding.
The mortgage and resale problem
This is the issue that catches homeowners out. When foam is sprayed onto the underside of a roof:
- It covers the rafters and felt, so a surveyor can no longer inspect the timbers for rot, leaks, or insect damage
- Where ventilation is reduced, trapped moisture can lead to condensation and timber decay behind the foam
- Removal is messy and costly, often requiring the roof covering to be stripped
Because of this, many lenders and their surveyors treat spray foam as a red flag. Mortgage applications on affected homes have been declined or made conditional on the foam being removed and the roof inspected — which can delay or derail a sale. Even where a lender proceeds, buyers may negotiate hard on price.
If you are buying, selling, or planning to remortgage, this risk usually outweighs any performance benefit.
What it costs (in prose, no grant)
Because there is no SEAI grant, you pay the full price yourself. Spray foam is generally more expensive per square metre than approved alternatives, and a full roof can run to several thousand euro depending on area, foam type, and access. With no grant to offset it — and a possible removal bill later — the lifetime cost picture is poor compared with grant-eligible measures. If you do get quotes, get three in writing and ask specifically how roof ventilation and future inspection will be handled.
Grant-eligible alternatives
You can achieve the same comfort and energy savings with measures SEAI actually supports:
Standard attic insulation — mineral wool or other approved materials laid at ceiling level is the lowest-cost, highest-value option and is fully grant-eligible:
| Dwelling | Attic grant |
|---|---|
| Detached | €2,000 |
| Semi-detached / end-terrace | €1,500 |
| Mid-terrace | €1,400 |
| Apartment | €1,100 |
Rafter (warm roof) insulation — where you need to insulate at roof level (for a converted attic room), approved rigid-board or mineral-wool systems between and over the rafters are grant-supported and do not bury the timbers in foam:
| Dwelling | Rafter grant |
|---|---|
| Detached | €3,000 |
| Mid-terrace | €2,000 |
| Apartment | €1,500 |
For the full picture on insulating the roof properly — including ventilation and how the warm-roof versus cold-roof choice affects your home — see our guide to attic insulation. The insulation grants guide lists which measures qualify, and how to improve your BER rating shows where attic work fits in a wider plan.
The bottom line
Spray foam offers a continuous seal, but it is not grant-eligible and can cause genuine mortgage, survey, and resale headaches. For the large majority of Irish homes, standard attic or rafter insulation delivers the same benefit, attracts a SEAI grant, and keeps your roof inspectable — a better outcome on cost, comfort, and resale.
Plan the right roof upgrade for your home: Check your SEAI grant eligibility or browse all our insulation guides.