The Great British Insulation Scheme pays up to £1,600 toward cavity-wall and loft insulation for eligible households – here is the 2026 cap breakdown
The Great British Insulation Scheme (GBIS) is a government-funded programme that helps pay for cavity-wall and loft insulation in homes that need it most. In 2026, the maximum grant per measure is £1,600 for cavity-wall insulation and £1,600 for loft insulation, though most households receive a lower amount depending on property size and the type of insulation installed (DESNZ, 2026). The scheme is funded by energy suppliers under the Energy Company Obligation (ECO) framework and administered by Ofgem.
The actual grant you receive is calculated based on the number of walls or loft area being insulated, not a flat rate. For a typical three-bedroom semi-detached house, cavity-wall insulation costs around £800–£1,200 to install, and loft insulation (top-up from 60mm to 270mm) costs roughly £500–£900. The grant covers the full installation cost up to the £1,600 cap per measure, so many households pay nothing at all (Ofgem, 2026).
GBIS eligibility criteria for England, Scotland, and Wales in 2026
To qualify for GBIS, your home must have an Energy Performance Certificate (EPC) rating of D, E, F, or G, and have uninsulated cavity walls or a loft with less than 60mm of existing insulation (GOV.UK, 2026). There are two routes to qualify.
The income-based route is open to households with a total annual income below £31,000, or below £36,000 if you live in certain postcodes in London and the South East. The benefits-tested route covers anyone receiving Universal Credit, Pension Credit, Child Tax Credit, Working Tax Credit, Income Support, income-based Jobseeker’s Allowance, or income-related Employment and Support Allowance (Ofgem, 2026).
The property must be owned or privately rented (with landlord consent). Social housing tenants are not eligible for GBIS; they can access insulation through separate social housing schemes (GOV.UK, 2026).
Quick numbers – key GBIS figures for 2026
| Measure | Grant cap | Typical annual saving | Installation time | U-value improvement |
|---|---|---|---|---|
| Cavity-wall insulation | £600–£1,600 | £160–£240 | 1–2 hours | Pre ~1.5 W/m²K, post ~0.3 W/m²K |
| Loft insulation (top-up to 270mm) | £400–£1,600 | £180–£285 | 2–4 hours | Pre ~0.5 W/m²K, post ~0.16 W/m²K |
Savings figures are based on a typical gas-heated three-bedroom semi-detached home in England, Scotland, and Wales (Energy Saving Trust, 2026). U-value improvements show how much less heat escapes after installation (EST U-value calculator, 2026). Actual savings depend on your property size, heating system, and energy tariff.
The complete walkthrough – how to apply for GBIS in 2026 step by step
Applying for GBIS is straightforward and requires no upfront payment from you. Here is the step-by-step process.
Step 1: Check eligibility. Use the GOV.UK eligibility checker at gov.uk/great-british-insulation-scheme. You will need your postcode, property type, and current insulation status (GOV.UK, 2026).
Step 2: Find an approved installer. Only use MCS-certified installers listed on the Ofgem-approved register. Do not use unregistered traders, as the funding cannot be claimed without proper certification (Ofgem, 2026).
Step 3: Free survey. The installer visits your home to assess cavity-wall suitability, loft access, and existing insulation depth. They measure the area and check for any damp or structural issues.
Step 4: Installer applies for funding. The installer submits the GBIS funding application on your behalf. Approval typically takes 2–4 weeks (GOV.UK, 2026).
Step 5: Installation and completion. The work is completed in one day for both measures. The installer submits completion paperwork to Ofgem, and you should receive a certificate of installation.
How GBIS compares with ECO4 – which scheme covers what in 2026
GBIS and ECO4 run alongside each other but cover different types of insulation and heating upgrades. GBIS covers only cavity-wall and loft insulation, while ECO4 covers solid-wall insulation, underfloor insulation, room-in-roof insulation, park-home insulation, and heating upgrades including boilers, heat pumps, and solar PV (Ofgem, 2026).
GBIS is a single-measure scheme – you can get one insulation type per property. ECO4 can fund multiple measures in the same home, such as cavity-wall insulation plus a heat pump. Both schemes require an EPC rating of D, E, F, or G, but ECO4 also has a low-income priority group that can access more generous funding (DESNZ, 2026).
A key difference is property value. GBIS has no cap on property value. ECO4 is limited to properties with a council tax band A–D in England and A–E in Scotland and Wales (Ofgem, 2026).
Compare ECO4 eligibility with GBIS side by side
How to verify a GBIS installer – MCS certification and TrustMark registration
All GBIS installations must be carried out by an installer certified under the Microgeneration Certification Scheme (MCS) for cavity-wall and loft insulation. You can check the MCS public register at mcscertified.com (MCS, 2026).
Installers must also hold TrustMark registration, a government-endorsed quality scheme that covers consumer protection and workmanship standards. Verify registration at trustmark.org.uk (TrustMark, 2026).
If the installer bundles any gas-safe work (such as boiler upgrades under ECO4), they must be registered with the Gas Safe Register. For any electrical work, they need NICEIC or NAPIT registration (Gas Safe Register, 2026).
How to check if an insulation installer is legit
Does GBIS cover solid-wall insulation in 2026?
No. GBIS funds only cavity-wall insulation and loft insulation. Solid-wall insulation, whether internal or external, is not covered under this scheme (Ofgem, 2026).
If your home has solid walls (typically pre-1930s properties), you must apply for solid-wall insulation through ECO4 if you are eligible, or pay privately. The Home Energy Scotland Grant and Loan also offers funding for solid-wall insulation in Scotland (DESNZ, 2026). Expect solid-wall insulation to cost between £8,000 and £22,000 depending on property size and whether you choose internal or external insulation.
Frequently Asked Questions
Up to £1,600 per measure for cavity-wall or loft insulation. The actual amount depends on the size of your property and the type of insulation installed, according to DESNZ and Ofgem.
Households with an EPC rating of D, E, F, or G and uninsulated cavity walls or loft insulation under 60mm. You must either have an income below £31,000 (£36,000 in some areas) or receive qualifying benefits, per GOV.UK.
Yes, for many households. The grant covers the full installation cost up to the £1,600 cap per measure, so you pay nothing if the work costs less than that, according to Ofgem.
Yes, cavity-wall insulation is a core measure under GBIS. The maximum grant is £1,600, and typical installation for a 3-bed semi costs £800-£1,200, per DESNZ.
Yes, loft insulation is covered, including top-ups from 60mm to 270mm. The grant is up to £1,600, and typical costs for a 3-bed semi are £500-£900, per Ofgem.
