PRICE GUIDE · TRADES & CONSTRUCTION · 2026–2027
Cavity Wall Insulation cost in the UK
£1,000–£4,600 per job. Typically £2,500.
House size decides most of it: cavity wall insulation costs £1,000 for a flat up to £4,600 for a detached home, with about £2,500 typical. Bead, wool or foam, the width and condition of the cavity, and access to every wall also move the price.
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HOW MUCH IT COSTS
How much does cavity wall insulation cost in the UK?
| Low end | £1,000 | a flat or small terrace with clear cavities |
|---|---|---|
| Typical | £2,500 | what most people pay |
| High end | £4,600 | a large detached house with every wall to fill |
Locufy guide prices for 2026–2027. Updated 2026. A national range, not a quote — enter your town above for real prices from the builders and trades near you.
What moves the price
- Size and type of home — a mid-floor flat has far less external wall to insulate than a detached house
- Insulation material — mineral wool, polystyrene bead and foam are priced differently per square metre of cavity wall
- Condition of the cavity — old insulation, rubble or narrow gaps may need extraction or rule the wall out
- Access — tall gables, conservatories and extensions against the wall make drilling and filling slower
- Exposure to driving rain — homes on exposed western and coastal sites need a careful survey before filling
- Grant eligibility — households on certain benefits or in low council tax bands may have the insulation funded
Building and repair prices in the UK are up 6% over five years (ONS Consumer Price Inflation, Services for maintenance and repair, to 2026 August). Five years ago a typical cavity wall insulation would have cost about £950 — an estimate from today's guide price and that index, not a recorded price. Source: ONS MM23 D7DO →
WHAT YOU GET
What a cavity wall insulation booking includes
Takes: Two to six hours for most homes, with the installer working entirely from outside. Not included: Removing failed old insulation, repairs to brickwork or pointing, and insulating the loft or floors are priced separately — see the related guides below.
WHAT PEOPLE BOOK
Common cavity wall insulation jobs
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Cavity Wall Insulation near you, with prices shown
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How to pay less
- Check whether you qualify for the Great British Insulation Scheme or ECO4, which can fund cavity wall insulation in full
- Get the loft insulated at the same visit, as many insulation installers price both jobs together
- Ask for the cavity wall survey to be free with the installation, which many installers offer
Before you book
- Ask whether the installer issues a CIGA or similar guarantee for the cavity wall insulation work
- Ask for a borescope survey, as cavity walls on exposed sites can let rain across if filled badly
- Check the cavity walls have no damp, cracked render or failed pointing that should be fixed first
- If you live in a flat or leasehold house, get the freeholder's permission before the walls are drilled
Cavity Wall Insulation cost: questions people ask
£1,000–£4,600 per job, about £2,500 typical. A mid-floor flat costs least; a large detached house with every wall to fill costs most.
Two to six hours for most homes. The work is done from outside, so you rarely need to move furniture.
Possibly. The Great British Insulation Scheme and ECO4, run through energy suppliers, fund insulation for households on certain benefits or in lower council tax bands, so check before you pay.
Most homes built with cavity walls are, but walls exposed to driving rain, very narrow cavities or timber-framed construction may not be. A proper survey settles it.
Extracting old insulation, brickwork repairs and insulating other parts of the house, such as the loft or floors, cost extra.
They are Locufy guide prices for the UK, worked out from published UK insulation cost guides — a national range, not a quote. Your home's size and walls set the real figure.