How much does cavity wall insulation cost in 2026?
A private cavity wall insulation install typically costs from about £795 for a mid-terrace house to about £3,795 for a large detached house on our guide ranges, depending on wall area, access and material. The Energy Saving Trust puts a typical Great Britain install at around £2,200. Homes currently pay no VAT on the installation.
What changes the price
- Wall area: house type, number of storeys, extensions and gables.
- Material: bonded bead usually costs a little more than mineral wool.
- Access: conservatories, lean-tos and three-storey walls may need towers or scaffold.
- Repairs found at survey, priced separately.
- Whether it is a first fill, a top-up or a removal and refill.
Will it pay back?
Energy Saving Trust estimates at July 2026 prices for a gas-heated home are around £380 a year for a detached house, £200 for a semi, £160 for a detached bungalow and £110 for a mid-terrace or mid-floor flat. The Energy Saving Trust says most households recoup the cost within about five years.
VAT
Installing insulation in a home is zero-rated for VAT until 31 March 2027, then 5%. Supply-only materials and most commercial work are standard-rated.
Guide price table
| Cavity wall insulation, bonded bead | Guide price |
|---|---|
| Detached house | £2,295–£3,795 |
| Semi-detached house | £1,495–£2,495 |
| End-terrace house | £1,295–£2,195 |
| Detached bungalow | £1,295–£2,195 |
| Semi-detached bungalow | £895–£1,595 |
| Mid-terrace house | £795–£1,395 |
No VAT is charged on installing insulation in homes until 31 March 2027 (then 5%). Guide ranges only: the fixed price is confirmed in writing after a free survey, before any work starts, and anything that could not be seen at survey is agreed with you first.
Related services
Sources: Energy Saving Trust: cavity wall insulation; Which?: cavity wall insulation costs and savings (EST figures, July 2026 prices); HMRC: VAT on energy-saving materials (Notice 708/6).