The EPC register calls this a room-in-roof insulation. Priced from the recommendations on 629,099 current certificates in England & Wales — not installer marketing.
The register’s indicative installed cost, and the payback at this measure’s typical saving.
| Property | Homes | Installed cost | Saving / yr | Payback |
|---|---|---|---|---|
| Detached bungalow | 35,394 | £2,100 | £241 | 8.7 yrs |
| End-Terrace bungalow | 707 | £2,100 | £241 | 8.7 yrs |
| Mid-Terrace bungalow | 1,672 | £2,100 | £241 | 8.7 yrs |
| Semi-Detached bungalow | 27,638 | £2,100 | £241 | 8.7 yrs |
| Detached flat | 1,216 | £2,100 | £241 | 8.7 yrs |
| Enclosed End-Terrace flat | 522 | £2,100 | £241 | 8.7 yrs |
| End-Terrace flat | 5,701 | £2,100 | £241 | 8.7 yrs |
| Mid-Terrace flat | 15,529 | £2,100 | £241 | 8.7 yrs |
| Semi-Detached flat | 5,865 | £2,100 | £241 | 8.7 yrs |
| Detached house | 130,000 | £2,100 | £241 | 8.7 yrs |
| Enclosed End-Terrace house | 5,356 | £2,100 | £241 | 8.7 yrs |
| Enclosed Mid-Terrace house | 9,640 | £2,100 | £241 | 8.7 yrs |
Savings are the measure’s share of the home’s own certificate saving, estimated the same way the Upgrade Plan estimates it, then taken across every home recommended this measure.
Room-in-roof insulation typically adds 7.9 EPC points, at about £266 a point. A grade band is 11–14 points wide, so on its own it rarely moves a whole grade — it is bought for the points, and combined with the other cheap measures on the list.
From the grants registry, verified 20 August 2026 · all grants
Exact cost, saving and grades gained — from your home’s own certificate.