Guide
How much does external wall insulation cost in 2026?
External wall insulation typically costs £105–£170 per m² of wall in 2026, plus scaffolding, depending mainly on the insulation board and the finish. A three-bed semi with EPS and silicone render usually comes to about £10,200–£17,700 including scaffold; brick-slip finishes and breathable wood fibre systems cost more. Installing insulation in a home is zero-rated for VAT until 31 March 2027.
What decides the price per m²?
- Insulation board — EPS is the least expensive, mineral wool and phenolic cost more, wood fibre the most.
- Thickness — thicker boards cost a little more but rarely change the price dramatically.
- Finish — silicone, acrylic and mineral renders are similar; brick slip adds roughly £70–£120 per m².
- Detailing — window and door count, bays, eaves extensions and services on the wall add labour.
- Access — scaffold, licences for pavement scaffolds and difficult rear access.
Typical totals by house type
| Property | Typical wall area | Guide total (incl. scaffold) |
|---|---|---|
| Mid-terrace (front and rear) | 40–55 m² | £5,100–£9,600 |
| End-terrace | 65–80 m² | £8,200–£14,000 |
| Three-bed semi | 80–100 m² | £10,200–£17,700 |
| Detached house | 120–160 m² | £15,400–£28,000 |
| Bungalow | 55–75 m² | £6,700–£12,800 |
Worked from our EPS and silicone render rate (£105–£145 per m²) plus our scaffold allowances. Mineral wool, wood fibre and brick slip cost more. These are totals: installing insulation in a home is zero-rated for VAT until 31 March 2027. Your survey fixes the price.
What extras should I expect?
Most quotes include cill extensions, beads, trims and re-fixing downpipes and lights. Items that vary are extending the roofline where eaves are shallow, moving gas meters (by the gas network), extending boiler flues (by a Gas Safe engineer), and repairs found once old render is removed.
Is VAT charged?
Installing insulation for walls in homes is currently zero-rated for VAT in Great Britain until 31 March 2027, then 5% from 1 April 2027. Northern Ireland has followed the same zero rate since 1 May 2023. Scaffolding supplied as part of the insulation job is part of the same zero-rated supply. Render-only work and repairs are normally standard-rated at 20%.
Questions
Is EWI cheaper than internal insulation?
Per m², internal insulation is usually cheaper (roughly £75–£130), but moving fittings, redecorating and lost space narrow the gap on whole-house jobs.
Why do EWI quotes vary so much?
Different systems, thicknesses and especially different levels of detailing. Compare the specification line by line, not just the total.
Can I spread the cost?
Some owners do one elevation at a time. It costs more overall because scaffold and set-up are repeated.