Cavity wall insulation grant: what still funds it in 2026

Where cavity wall grants stand in 2026

For years, most people who got cavity wall insulation for free got it through an energy supplier scheme. That is changing. The Warm Homes Plan, published in January 2026, brought supplier obligations to a close: the Great British Insulation Scheme ended on 31 March 2026, and ECO4 runs until 31 December 2026 after a nine-month extension aimed at an orderly closure rather than new delivery targets. The government’s replacement for low-income households is grant funding, delivered first through the Warm Homes: Local Grant.

How cavity wall insulation works under the Warm Homes: Local Grant

Cavity wall insulation is on the guidance’s list of energy performance measures, so it is paid from the energy performance pot, capped at £16,600 per home on average across the council’s project. The same pot also pays for other fabric and smart measures, so cavity wall insulation often sits in a package with loft insulation, draughtproofing or solar PV.

It is not a stand-alone offer. The sequence is:

1. You apply and the council verifies your household is eligible.
2. A retrofit assessor surveys the whole home to PAS 2035:2023, including the walls, ventilation and signs of damp.
3. The retrofit coordinator decides whether the cavity suits filling and what else the home needs, aiming for EPC C where the caps allow.
4. An installer certified to PAS 2030 and registered with TrustMark fills the cavity, with a guarantee in place before work starts.
5. The measure is lodged with TrustMark and the home gets a new EPC.

Who qualifies

The household must be on a low income: an eligible postcode, a listed means-tested benefit, or a gross household income of £36,000 or less (or under the after-housing-costs limit). The home must be in England, privately owned or privately rented, already lived in, and rated EPC D to G. Owner occupiers and tenants pay nothing. Landlords get their first home fully funded and pay 50% after that.

When cavity walls are not the answer

Not every wall with a cavity should be filled, which is why the assessment comes first. PAS 2035 is a whole-house standard: it looks at the building as a system, including its condition, moisture and ventilation, before any measure is specified. If a cavity is unsuitable, the coordinator should propose something else within the caps.

Homes with solid walls, typical of older terraces, need solid wall insulation instead: external or internal. That is a bigger, more expensive job with its own rules, covered on the external wall insulation grant page.

Previously filled cavities

If the cavity was filled under an earlier scheme, the grant cannot fund the same measure twice. If the old fill has failed, the delivery guidance allows councils to use their administration and ancillary budget for failed insulation or extraction costs, but only where those costs are not covered by an insurance or guarantee from the previous installation. Check whether you have a guarantee certificate from the original work.

Using the grant alongside ECO4 before December

ECO4 and the Warm Homes: Local Grant can both touch the same home, but not the same measure. The guidance says any ECO4 work should happen wholly before or wholly after the Warm Homes: Local Grant work, and each scheme needs its own post-installation EPC and TrustMark lodgement. The EPC after the first scheme is what shows whether the home is still rated D to G and so still eligible for the second. ECO4’s closure explained.

If you do not qualify

You can still pay for cavity wall insulation yourself. Installation of insulation in a home is zero-rated for VAT until 31 March 2027, then 5%. Choose an installer registered with TrustMark and certified for the measure, and ask for the guarantee details in writing before work starts.