The EPC register calls this a solid wall insulation. Priced from the recommendations on 4,401,238 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 | 63,461 | £9,000 | £143 | 62.9 yrs |
| End-Terrace bungalow | 4,639 | £9,000 | £143 | 62.9 yrs |
| Mid-Terrace bungalow | 6,272 | £9,000 | £143 | 62.9 yrs |
| Semi-Detached bungalow | 42,226 | £9,000 | £143 | 62.9 yrs |
| Detached flat | 60,368 | £9,000 | £143 | 62.9 yrs |
| Enclosed End-Terrace flat | 34,014 | £9,000 | £143 | 62.9 yrs |
| Enclosed Mid-Terrace flat | 26,480 | £9,000 | £143 | 62.9 yrs |
| End-Terrace flat | 186,363 | £9,000 | £143 | 62.9 yrs |
| Mid-Terrace flat | 462,117 | £9,000 | £143 | 62.9 yrs |
| Semi-Detached flat | 232,980 | £9,000 | £143 | 62.9 yrs |
| Detached house | 402,710 | £9,000 | £143 | 62.9 yrs |
| Enclosed End-Terrace house | 16,561 | £9,000 | £143 | 62.9 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.
Solid wall insulation typically adds 6.2 EPC points, at about £1,456 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.