Typical 2026 UK costs by house type, the savings you could make, and how to get a fair price.
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Cavity wall insulation is one of the best value ways to warm up a home built after the 1920s. For a typical property the Energy Saving Trust puts the cost at around £2,200, but it ranges from about £950 to £3,900 depending on the size and number of external walls. Here is the full breakdown by house type, what drives the price, and how to make sure you pay a fair rate. For how it works, suitability and the damp questions, see our full cavity wall insulation guide.
These are typical figures for England, Scotland and Wales. A detached house can save around £380 a year on energy bills, the most of any property type.
| House type | Typical installation cost | Typical annual bill saving |
|---|---|---|
| Detached house | £3,900 | £380 |
| Semi-detached house | £2,200 | £200 |
| Mid-terrace house | £1,100 | £110 |
| Detached bungalow | £1,700 | £160 |
| Mid-floor flat | £950 | £110 |
Cost and saving figures: Energy Saving Trust (England, Scotland & Wales), verified August 2026. These are typical estimates and your own quote will vary by home. Always compare quotes.
Priced by wall area, the material sets the rate. As a guide, glass wool costs around £25 to £30 per m² and polyurethane foam, the best insulator of the common types, around £30 to £65 per m² (materials, Checkatrade, July 2026). Most homes are quoted by property size rather than per m², so use these as a sense check.
The biggest factor is simply how much wall you have, which is why a detached house costs more than a flat. Other things that move the price include how easy your walls are to access, the condition of the brickwork and pointing, your location, and the material used (usually polystyrene beads or mineral wool). Homes joined to a neighbour need a cavity barrier fitted, which can add a little to the job.
For most suitable homes it is well worth it. Around a third of the heat in an uninsulated home escapes through the walls, so filling the cavity makes a real difference to warmth and to your bills. On the Energy Saving Trust figures above it typically pays for itself over about a decade, and a lot sooner if you qualify for a grant. It is not suitable for every home though, so an installer survey is essential for very exposed, flood-prone or narrow-cavity walls.
Two things bring the cost down. First, government support: funding for insulation is changing under the Warm Homes Plan, so check our guide to UK insulation grants in 2026 and confirm current schemes before you rely on them. Second, and within your control today, comparing quotes: prices for the same job vary widely between installers, so getting several quotes is the simplest way to avoid overpaying.
Always get quotes from more than one vetted, accredited installer, check the work is guaranteed (for cavity wall insulation this is usually a 25-year CIGA guarantee), and do not feel pressured to accept the first price. Tell us about your home and we will match you with vetted installers so you can compare no cost quotes side by side.
For a typical home in England, Scotland and Wales the Energy Saving Trust puts cavity wall insulation at around £2,200, but it ranges from about £950 for a mid-floor flat to around £3,900 for a detached house, depending on the size and number of external walls. Your own quote will vary, so it pays to compare several.
According to the Energy Saving Trust, annual bill savings range from around £110 a year for a flat or mid-terrace up to about £380 a year for a detached house in England, Scotland and Wales. Around a third of an uninsulated home's heat escapes through the walls, so the warmth benefit is significant too.
For most suitable homes, yes. It makes the home warmer and cuts heat lost through the walls. Based on Energy Saving Trust figures it typically pays for itself over roughly a decade through lower bills, and much faster if a grant covers part or all of the cost. It is not suitable for very exposed, flood-prone or narrow-cavity walls, which is why a survey matters.
There may be. Government support for insulation is changing under the Warm Homes Plan, and schemes and eligibility move quickly. See our guide to UK insulation grants in 2026 for the current picture, and always confirm live scheme details before relying on them.
Get quotes from several vetted, accredited installers rather than accepting the first price. Tell us about your home and we will match you with installers so you can compare no cost quotes side by side.
Tell us about your home and we will match you with vetted installers so you can compare no cost quotes and see a fair price.
Insulation Advice Centre