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External Wall Insulation

Insulate solid walls from the outside with insulation boards and render. A big job, but funding may help eligible households

Around £15,000 for a 3-bed semi Save around £140-£500/year Check TrustMark registration
Step 1 of 2What you need

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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. Free, no obligation.

Which improvements are you considering?Tick all that apply.
How big is your home?
Does anyone in the home receive benefits?Some funding, such as ECO4, depends on this.

No contact details needed until the next step. Your answers stay on this page until you send your enquiry.

What is External Wall Insulation?

External Wall Insulation (EWI) involves adding insulation to the outside of solid walls, then covering it with render or cladding. Homes built before the 1920s are more likely to have solid walls, which have no cavity to fill.

About a third of the heat lost from an uninsulated home escapes through the walls. The Energy Saving Trust estimates solid wall insulation saves around £140-£500 a year depending on your home (July 2026 prices). EWI doesn't reduce your floor area and should improve weatherproofing, but check with your council whether you need planning permission, especially in a conservation area.

Key Benefits

Funding May Help

ECO4 (until 31 December 2026) or your council may fully or partly fund it for eligible homes

Lower Bills

Around £280/year for a semi-detached house (Energy Saving Trust)

Keeps Floor Space

Fitted outside, so your rooms stay the same size

Refresh Appearance

Renews the look of outer walls; check planning rules first

Weather Protection

Should improve weatherproofing and protect the brickwork

Ask for a Guarantee

TrustMark solid wall insulation companies offer a 25-year guarantee

External Wall Insulation Costs

Around £15,000
Typical cost for a 3-bed semi, whole house done in one go

Funding May Help With the Cost

ECO4 ends on 31 December 2026 and work must be finished by then. It is not a grant: work may be fully or partly funded, and you may be asked to contribute. In England, councils also run the Warm Homes: Local Grant (EPC D-G, household income usually £36,000 or less). The Great British Insulation Scheme closed on 31 March 2026.

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: ECO4 or Warm Homes: Local Grant.

Had EWI Fitted Under ECO4 or GBIS?

The Energy Saving Trust reports that 98% of homes fitted with external wall insulation under ECO4 and the Great British Insulation Scheme have problems that need fixing. TrustMark is offering affected homes a free Find & Fix audit.

£140-£500/year
Typical bill savings, flat to detached house (around £280 for a semi)

Typical costs, last reviewed September 2026. Source: Energy Saving Trust, July 2026 prices (unsubsidised, gas-heated home).

Quick Grant Finder

Answer up to three quick questions to see which schemes may be worth checking

Ready to Insulate Your Solid Walls?

Sending an enquiry is free. Better Home Hub, which runs this site, introduces installers who may be able to help. Check they are TrustMark registered before you agree to work.

Request Quotes from Installers