External wall insulation (EWI) — often called “the wrap” — typically costs €15,000–€30,000 for a detached Irish home before grant, falling to roughly €10,000–€20,000 for a semi-detached. It is the most comprehensive wall upgrade available, and SEAI grants cover a meaningful chunk of the bill.
What is external wall insulation?
EWI fixes rigid insulation boards to the outside of your external walls and finishes them with a weatherproof render or cladding. Because the insulation sits on the outside, it warms the whole wall, eliminates most thermal bridges, and leaves your internal room sizes untouched.
It is the go-to solution for solid-walled homes (pre-1940s stone or single-skin block) and for anyone doing a deep retrofit aiming for a B BER.
EWI cost per square metre
The single biggest cost driver is wall area. Installed pricing in Ireland generally runs:
| Item | Typical installed rate |
|---|---|
| EWI, lower end (per m²) | 80 EUR/m² |
| EWI, higher end (per m²) | 150 EUR/m² |
These rates include the boards, adhesive, mechanical fixings, basecoat, mesh, and a standard render finish. A premium silicone or brick-effect render, awkward access, or extensive detailing around windows pushes you toward the higher end.
A typical semi-detached has 90–130m² of treatable wall; a detached house often 150–220m². Multiply your wall area by the rates above for a rough materials-and-labour estimate, then add scaffolding (usually €1,000–€2,500) and any preparation work.
Costs vary by contractor and region. Get three written quotes from SEAI-registered installers before committing.
SEAI grants for external wall insulation
Grants are set by dwelling type and paid after completion and inspection:
| Dwelling | Grant |
|---|---|
| Detached | €8,000 |
| Semi-detached / end-terrace | €6,000 |
| Mid-terrace | €3,500 |
| Apartment | €3,000 |
To qualify, your home must have been built and occupied before the relevant SEAI cut-off date, the work must be done by an SEAI-registered contractor, and a BER assessment is required after the works. See our insulation grants guide for the full eligibility rules.
Total cost example
For a semi-detached house with around 110m² of wall:
- Installed EWI at the mid-range rate: roughly €13,000–€16,000
- Less the SEAI semi-detached grant (€6,000)
- Net cost: commonly €9,000–€13,000
EWI remains a significant investment even after grant — but it delivers the biggest single jump in wall performance and is the only wall measure that also re-weatherproofs and refreshes the exterior.
Pros and cons of “the wrap”
Pros
- No loss of internal room size
- Treats the whole wall, including corners and lintels where heat normally escapes
- Re-renders and weatherproofs the exterior in one go
- Less disruptive than internal dry-lining — you stay living in the house
Cons
- Highest upfront cost of the wall options
- Changes the external appearance and the building line at the eaves and reveals
- Needs careful detailing around windows, doors, gutters, and the damp-proof course
Planning and render notes
For most houses EWI is exempt from planning permission, but protected structures and homes in Architectural Conservation Areas may need consent — and so may any work that projects over a boundary. Always check with your local authority first.
On the render: thin-coat silicone renders shed dirt and resist algae better than older sand-and-cement finishes, especially on exposed or north-facing walls. Make sure window sills, gutters, and downpipes are extended to clear the new, thicker wall, and that the system is detailed to stop water tracking behind the boards.
How EWI compares
If you are weighing your options, compare EWI against the alternatives in our guide to wall insulation types. For solid walls the main rival is dry-lining — see internal wall insulation cost — while homes with unfilled cavities should usually start with cheaper cavity wall insulation. If you are bundling several measures, a managed retrofit may suit; read One Stop Shop vs individual grants.
Not sure which measures your home qualifies for? Check your SEAI grant eligibility or browse all our insulation guides.