Cavity Wall Insulation Cost Calculator
See typical cavity wall insulation costs and bill savings by house type, based on Energy Saving Trust figures (July 2026 prices), and which funding schemes are still open.
Estimate Your Cavity Wall Insulation Cost
Typical costs, last reviewed September 2026. Source: Energy Saving Trust, July 2026 prices, gas-heated home. Your quote and savings will depend on your home.
You may be able to get funding
With an EPC of D, your home is in the band ECO4 uses (until 31 December 2026). ECO4 may fully or partly fund the work if you get qualifying benefits or your council accepts you, for example with gross income under £31,000; you may be asked to contribute. In England, the Warm Homes: Local Grant covers privately owned homes rated D to G, usually for household incomes of £36,000 or less.
Get free quotes from local insulation installers
Tell us about the job and we’ll find up to 3 local insulation installers who cover your area and ask them to contact you with a quote. Your answers above go with your enquiry. Free, no obligation.
Send a Free EnquiryWhat is Cavity Wall Insulation?
Cavity wall insulation fills the gap between the inner and outer layers of your walls with insulating material, so less heat escapes through them.
Many UK homes have cavity walls: two layers of brick or block with a gap between them. A surveyor can confirm your wall type, whether the cavity is already filled and whether the walls are suitable.
Typical Cavity Wall Insulation Costs
Semi-detached house
Typical cost: £2,200
Saves around £200 a year
Detached house
Typical cost: £3,900
Saves around £380 a year
Mid-terrace house
Typical cost: £1,100
Saves around £110 a year
Detached bungalow
Typical cost: £1,700
Saves around £160 a year
Mid-floor flat
Typical cost: £950
Saves around £110 a year
Typical costs, last reviewed September 2026. Source: Energy Saving Trust, July 2026 prices; average unsubsidised install cost, savings for a gas-heated home. ECO4 or the Warm Homes: Local Grant may reduce or cover the cost for eligible households, but funding is not guaranteed.
Funding for Cavity Wall Insulation
ECO4 (ends 31 December 2026)
ECO4 is not a fixed grant. Energy suppliers and installers decide what to offer, so work may be fully or partly funded and you may be asked to contribute.
Warm Homes: Local Grant (England)
Run by local councils until 31 March 2028. Owner-occupiers do not pay; landlords may need to contribute. Depends on your council's funding.
The Great British Insulation Scheme closed on 31 March 2026 and was not extended. UK Energy Partnership is run by Harber Glaves Trading Ltd. We are not a government body and cannot decide who gets funding — check eligibility with the official scheme, for example Warm Homes: Local Grant on GOV.UK or our ECO4 guide.
Benefits of Cavity Wall Insulation
Save Around £110 to £380 a Year
Depending on house type (Energy Saving Trust). Estimates, not guaranteed.
Warmer Home
Less heat escapes through your walls
Better EPC Rating
Insulating your walls can improve your EPC rating
Minimal Disruption
Installers usually work from outside, drilling small holes and filling them afterwards
Reduce Carbon Footprint
Around 350 to 1,200 kg less CO2 a year, depending on house type
Ask About a Guarantee
Ask whether the work will be covered by a CIGA guarantee, in writing, before work starts
Get Cavity Wall Insulation Quotes
Free to send an enquiry • We pass it to Better Home Hub • Funding is decided by the scheme, not us
Send a Free Enquiry