Cavity Wall Insulation Grants: Check If You Qualify for Free Cavity Wall Insulation
You may be able to get cavity wall insulation free or funded right now through ECO4, which runs until 31 December 2026 and is open to households on a qualifying benefit or referred by their council under LA Flex, or through the Warm Homes: Local Grant, which councils run in England. The Great British Insulation Scheme closed on 31 March 2026 and is no longer a route.
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A survey confirms whether your cavity walls are unfilled and suitable.
Page last reviewed for accuracy: 2 October 2026.
Cavity Wall Insulation at a Glance
| Cost to the household | Free if the work is funded under ECO4 or the Warm Homes: Local Grant |
| ECO4 | Open until 31 December 2026, via a qualifying benefit or an LA Flex referral |
| Warm Homes: Local Grant | England only, run by councils; delivery runs April 2025 to March 2028 |
| Great British Insulation Scheme | Closed on 31 March 2026 |
| Without a grant | You pay the installer directly; get more than one quote |
Sources: Ofgem (ECO4), Ofgem (GBIS) and GOV.UK (Warm Homes: Local Grant). A survey decides what is funded for your home.
What ApplyFreeBoiler.uk Actually Does
ApplyFreeBoiler.uk is run by Reliant Energy Solutions Ltd, an ECO4 heating and insulation installer. We're not the government or an energy supplier. We check whether you may qualify for ECO4 or LA Flex, survey your home and, where the work is funded under ECO4, install it. We are paid by the energy supplier for each ECO4 installation we complete, not by households (see our editorial policy). The Warm Homes: Local Grant is applied for through your council, so for that route we can tell you whether you may qualify, but the council decides.
Why Cavity Wall Insulation Matters
Walls are a major route for heat loss from an uninsulated home. If your home was built from the 1920s onwards, there's a good chance it has cavity walls: two layers of brick or block with a gap between them. That gap can be filled with insulating material to slow that heat loss.
Lower heating bills, with the saving depending on your property
Fewer cold spots and draughts — more even temperatures throughout the home
Reduced condensation risk — warmer internal wall surfaces mean less moisture forming on them
A better EPC rating, with the size of the improvement depending on your home
Lower carbon emissions — less gas or electricity burned to heat the same space
Do You Have Cavity Walls?
Before applying, it helps to know what kind of walls your home has.
Two quick checks you can do yourself:
- Measure the wall thickness at a door or window opening. 260mm–350mm typically means a cavity wall; narrower usually means solid.
- Look at the brick pattern. All bricks laid lengthways in an even pattern usually means a cavity wall. An alternating pattern (some bricks showing their short end) usually means a solid wall.
If your walls are rendered, clad, or you're still not sure, our surveyors will confirm it for you at no cost — there's no need to guess.
What Grants Cover Cavity Wall Insulation in 2026
Two routes currently fund free cavity wall insulation: ECO4, until 31 December 2026, and the Warm Homes: Local Grant in England.
The Great British Insulation Scheme closed on 31 March 2026 (work had to be completed before 1 April 2026), so it is no longer a route. No direct replacement is confirmed on Ofgem's GBIS page, so ECO4 and the Warm Homes: Local Grant are the routes to check instead.
| ECO4 | Warm Homes: Local Grant | |
|---|---|---|
| Who it's for | Households on a qualifying benefit, or referred by their council under LA Flex | Household income usually £36,000 a year or less, or a qualifying low-income postcode, or certain means-tested benefits |
| Where | England, Scotland, Wales | England (delivered via local councils) |
| Runs until | 31 December 2026 | Delivery runs April 2025 to March 2028 |
ECO4: the main route
To qualify under ECO4, your household generally needs:
Someone receiving a qualifying benefit: Child Benefit (subject to an income threshold), Housing Benefit, income-based Jobseeker's Allowance, income-related Employment and Support Allowance, Income Support, Pension Credit (Guarantee Credit or Savings Credit) or Universal Credit, or
A referral from your local council under ECO4 Flex (LA Flex), for households that do not get a qualifying benefit. Councils opt in and publish a Statement of Intent, and the routes include household income under £31,000, area-based targeting and a health condition made worse by a cold home
A home that is generally EPC band D to G, with separate rules for private rented and social housing
Unfilled cavity walls confirmed at survey
ECO4 is funded by energy suppliers under an Ofgem-administered obligation and ends on 31 December 2026, so if you are likely to qualify it is worth checking sooner rather than later. Ofgem's homeowners and tenants page lists the qualifying benefits. See also our ECO4 scheme guide and LA Flex guide.
How ECO4 treats cavity wall insulation
Cavity wall insulation is an eligible ECO4 measure, and ECO4 takes a whole-house approach. There are minimum insulation requirements: before certain heating measures can be funded, cavity wall and loft or roof insulation must already be installed or present, or be exempt. If your cavity is unfilled, insulation may therefore come first, which is why the survey looks at the whole home.
The detail is in Ofgem's ECO4 delivery guidance. Loft insulation falls under the same requirement, so see our loft insulation grant guide.
Warm Homes: Local Grant (England)
The Warm Homes: Local Grant is run by local councils in England and funds free energy upgrades, including insulation, for privately owned homes (owner-occupied or privately rented) with an EPC rating of D to G. You generally need one of:
Household income usually £36,000 a year or less, or
A home in a qualifying low-income postcode, or
Someone in the household receiving certain means-tested benefits
Apply at gov.uk/apply-warm-homes-local-grant and your council will then contact you. Our Warm Homes: Local Grant versus ECO4 comparison sets out the differences, and we can check whether you may qualify first.
If you don't qualify for either
You can still pay for cavity wall insulation directly. Get more than one quote, ask what guarantee comes with the work, and have a survey confirm your cavity is suitable before you commit. We can still arrange a survey either way.
Types of Cavity Wall Insulation
Your surveyor will recommend the right material for your cavity width and wall condition.
The most common material, made from recycled glass and sand. Fire resistant, non-toxic, and long-lasting. Best for standard cavity walls (50mm+ gaps).
Small beads with an adhesive coating, blown into the cavity. Quick to install and performs well in narrow or awkward cavities.
Expanding foam that fills irregular gaps thoroughly. Often used for older or non-standard cavity walls, with strong air-sealing properties.
How Installation Works
Property survey
A qualified surveyor checks cavity width, wall condition, and looks for any existing damp or structural issues that need resolving first.
Grant application and pre-installation checks
We handle the paperwork; the installer confirms any planning or neighbour-notification requirements.
Installation day
Small holes are drilled into the external mortar joints, insulation is blown in, and the holes are sealed and colour-matched. All the work happens from outside, so rooms don't usually need clearing.
Quality check
A post-installation inspection and your guarantee documentation.
Timescales: These depend on your survey, funding approval and installer availability. We confirm an installation date after your survey.
Guarantees: Installations normally come with a guarantee, usually through the Cavity Insulation Guarantee Agency (CIGA), and installers are TrustMark-registered — the government-endorsed standard for trades working in UK homes.
Is Your Property Suitable?
Most homes built between 1920 and 1990 with brick or block cavity walls are good candidates. A survey will confirm the specifics for your property:
Cavity wall insulation usually isn't recommended for homes with very narrow cavities, existing damp problems, or high weather exposure — a proper survey should always come before installation, not after.
Cavity Wall Insulation Removal: Who Pays?
Removing failed or damp cavity wall insulation is usually a claim against the original installer's guarantee, for example through CIGA, or a cost to the owner. Do not assume a grant covers it: ECO4 funds eligible measures on a whole-house basis, and a survey decides what it will fund for your home.
- Find your guarantee. Look for the guarantee paperwork from when the work was done, usually issued through the Cavity Insulation Guarantee Agency (CIGA). Start your claim with the original installer or CIGA.
- Get the cause checked. Damp after installation is often linked to an existing problem such as damaged brickwork, faulty guttering or a leaking roof. A survey can show whether the insulation is the cause.
- If there is no guarantee to claim on, removal is generally a cost to the owner. Blown fibre can be extracted with specialist vacuum equipment, so ask specialist contractors for quotes.
- Tell the surveyor about the earlier work. If you also qualify for ECO4 or the Warm Homes: Local Grant, the earlier insulation is assessed with the rest of the home, and the survey decides what is funded.
Yes. Privately rented homes can qualify under ECO4 through the tenant's eligibility, with the landlord's permission. The Warm Homes: Local Grant also covers privately owned homes in England, whether owner-occupied or privately rented, if they have an EPC rating of D to G.
Landlords: ECO4 has its own rules for private rented and social housing, set out in Ofgem's delivery guidance, and landlord contributions can apply under the Warm Homes: Local Grant, so check your council's terms. Our guide to landlord permission explains the consent step.
ECO4 covers cavity wall insulation across England, Scotland, and Wales. In Scotland, Home Energy Scotland can also offer additional advice and support alongside ECO4. In Wales, the Welsh Government's Nest scheme runs alongside ECO4 for eligible households. The Warm Homes: Local Grant, by contrast, currently applies to England only.
Bills, Comfort & Environmental Impact
Savings depend on your property size, current insulation and heating system, so we do not quote a figure here. The Energy Saving Trust publishes typical estimates by home type.
| Uninsulated | With cavity wall insulation | |
|---|---|---|
| Heating demand | Higher | Lower |
| Wall heat loss | Higher | Reduced |
| Condensation risk | Higher | Reduced |
- Property size and type, because more exposed wall means more heat loss to cut
- How much insulation the home already has
- Your heating system and how much you use it
Cutting wall heat loss reduces the gas or electricity burned for heating, lowering your home's carbon footprint. The exact CO₂ saving depends on your heating system and current energy source.
Common Myths About Cavity Wall Insulation, Debunked
Reality: When installed correctly in a suitable property, cavity wall insulation shouldn't cause damp — and by keeping wall surfaces warmer, it can actually reduce condensation risk. Damp problems after installation are usually linked to an issue that existed beforehand (damaged brickwork, faulty guttering, a leaking roof) and wasn't resolved first, which is exactly why a proper survey matters.
Reality: Cavity wall insulation can be removed if genuinely necessary: blown fibre can be extracted with specialist vacuum equipment, and beads can be removed via cavity access points. In practice, removal is rarely needed when a proper survey was carried out beforehand, and the original guarantee (usually through CIGA) is the first place to look if there is a problem with the work. See the removal section above for who pays.
Reality: Age alone doesn't rule a property out. Homes built between the 1920s and 1980s are the primary candidate group for cavity wall insulation — what actually matters is cavity condition, width, and whether any existing damp issues have been resolved.
Reality: All the work happens from outside. Installers drill small holes in the mortar joints, inject the insulation, and seal the holes to match your brickwork, with no need to clear rooms or move furniture.
Reality: For households that qualify, ECO4 and the Warm Homes: Local Grant can fund the installation in full, and a survey confirms what is funded for your home. If you do not qualify, get more than one quote and ask what guarantee comes with the work.
Frequently Asked Questions
Get answers to common questions about cavity wall insulation grants and installation process.
Is there a government grant for cavity wall insulation?
Yes, if you qualify. Free or funded cavity wall insulation is available through ECO4, which runs until 31 December 2026, and through the Warm Homes: Local Grant, which councils run in England. The Great British Insulation Scheme closed on 31 March 2026, so it is no longer a route. Which one applies depends on your benefits or income, your home's EPC rating and a survey.
Can you get free cavity wall insulation?
You can if you qualify. Eligible installations funded under ECO4 or the Warm Homes: Local Grant can be fully funded, and a survey confirms what is funded for your home. ECO4 is paid for by energy suppliers, and the Warm Homes: Local Grant is delivered by councils. If you do not qualify, you can still pay for the work yourself.
Who can get a cavity wall insulation grant?
Under ECO4 you generally need someone in the household on a qualifying benefit (such as Universal Credit, Pension Credit or Housing Benefit) or a referral from your council under LA Flex, plus a home that is generally EPC band D to G. Under the Warm Homes: Local Grant in England, household income is usually £36,000 a year or less, or the home is in a qualifying low-income postcode, or someone gets certain means-tested benefits. A survey must also confirm that your cavity walls are unfilled and suitable.
How do I know if I have cavity walls?
Homes built after the 1920s usually have cavity walls, and homes from the 1990s onwards are usually already insulated. Check by measuring your wall thickness (260 to 350mm suggests a cavity wall) or looking at the brick pattern, where even lengthways bricks usually mean a cavity wall. A survey confirms it.
Does cavity wall insulation cause damp?
Properly installed insulation in a suitable property shouldn't cause damp. Any existing issues such as damaged brickwork, faulty guttering or roof leaks need resolving before installation, which is what the pre-installation survey checks for.
Can I get cavity wall insulation if I rent, and are there grants for landlords?
Privately rented homes can qualify. Under ECO4 it is the tenant's eligibility (a qualifying benefit or an LA Flex referral) that counts, and the landlord must give permission. The Warm Homes: Local Grant in England also covers privately owned homes that are owner-occupied or privately rented, with EPC D to G, and landlord contributions can apply, so check your council's terms. Ofgem's ECO4 delivery guidance sets the tenure-specific rules.
Is cavity wall insulation removal covered by a grant?
Do not assume it is. Removing failed cavity wall insulation is usually a claim against the original installer's guarantee, for example through CIGA, or a cost to the owner. A survey decides what ECO4 will fund for your home.
Can I still get free cavity wall insulation through the Great British Insulation Scheme?
No. The Great British Insulation Scheme closed on 31 March 2026, and work had to be completed before 1 April 2026. No direct replacement is confirmed on official pages. ECO4 (to 31 December 2026) and the Warm Homes: Local Grant are the live routes.
How long does cavity wall insulation installation take?
The work is carried out from outside, so you don't usually need to clear rooms. Timescales depend on your survey, funding approval and installer availability, and an installation date is confirmed after your survey.
How long does cavity wall insulation last?
It's designed to last the lifetime of the building and normally comes with a guarantee, usually through the Cavity Insulation Guarantee Agency (CIGA). Keep your guarantee paperwork safe.
Ready to Check If You Qualify?
Check whether you may qualify for funded cavity wall insulation. A survey confirms what is funded for your home.