The most important thing to know about underfloor insulation grants in 2026
The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. Both schemes are strictly means-tested or property-specific, meaning you cannot simply apply for free insulation as a general homeowner.
The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. Crucially, you must use an MCS-certified installer to access any government grant, self-installation is not funded under any scheme (Ofgem, ECO4 Order, 2026).
Who qualifies for a fully funded underfloor insulation grant
Households receiving means-tested benefits, including Universal Credit, Pension Credit, Income Support, and Housing Benefit, qualify for 100% funding under ECO4 (Ofgem, ECO4 eligibility criteria, 2026). The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing.
The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. Owner-occupiers and private tenants (with landlord consent) qualify; social housing tenants are covered under separate schemes and should contact their housing provider directly.
Quick numbers grant amounts, savings, and payback
| Funding scenario | Cost to homeowner | Annual heating bill reduction | Payback time | Minimum floor area |
|---|---|---|---|---|
| ECO4 full grant | £0 (100% covered) | £100–£200 | Not applicable | No minimum stated |
| GBIS partial grant | 25–50% of £1,200–£2,500 | £100–£200 | 3–6 years | No minimum stated |
| Self-funded | £1,200–£2,500 | £100–£200 | 6–12 years | 50m² typical |
| Local authority loan | £0 upfront (repayable) | £100–£200 | Depends on loan term | Varies by council |
The average cost of underfloor insulation for a suspended timber floor is £1,200–£2,500, with annual savings of £100–£200 on heating bills (Energy Saving Trust, underfloor insulation cost and savings data, 2026). Payback for self-funded installations typically falls within 6–12 years (DESNZ, domestic energy efficiency statistics, 2026).
How to check if your suspended timber floor is eligible for a grant
An energy assessor or surveyor must confirm that your floor is uninsulated or has insulation below 50mm thickness, or a U-value above 0.70 W/m²K. Homes with existing insulation that meets current building regulations (U-value ≤ 0.25 W/m²K) are not eligible for grant-funded upgrades under any scheme (MCS, Installation standard for floor insulation, MIS 3005, 2026).
The floor must be accessible from below, for example, via a crawl space, cellar, or basement. Floors with no access void are ineligible for standard insulation because the material cannot be installed safely. A retrofit assessment compliant with PAS 2035 is required for ECO4-funded work to check for damp, ventilation, and structural issues before any insulation is fitted (PAS 2035:2023, retrofit assessment requirements).
How to book a retrofit assessment for underfloor insulation
What the grant actually pays for and what it does not cover
The grant covers insulation material, typically mineral wool, rigid foam boards, or natural fibre batts, and the labour for installation (Ofgem, ECO4 installation cost guidance, 2026). It also includes necessary preparatory work such as fitting netting or mesh to hold the insulation in place between joists, and installing a vapour control layer where needed to prevent moisture build-up.
The grant does not cover structural repairs to floor joists, replacement of rotten timber, or re-laying floorboards unless these are part of a wider renovation project (MCS, floor insulation installation standard, 2026). Ventilation upgrades, such as adding air bricks or sub-floor vents, are not automatically included, but may be funded separately under ECO4 if the retrofit assessment identifies a need.
The direct answer to “Can I get underfloor insulation for free?”
Yes, if your household income is below £31,000 (or you receive qualifying benefits) and your floor is uninsulated with an EPC rating of D or worse. No, if you are a homeowner with an EPC rating of A, B, or C, or if your floor already has insulation meeting 2026 building regulations (GOV.UK, Great British Insulation Scheme, 2026).
The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. Free installation is only available via an MCS-certified installer arranged through your energy supplier or local authority; you cannot apply directly for cash (Ofgem, ECO4 guidance, 2026).
How to verify an installer and avoid grant fraud
The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. Check the MCS register at mcscertified.com before agreeing to any work (MCS, Find an installer, 2026). TrustMark registration is also required for ECO4 work, verify the installer’s TrustMark licence number separately (TrustMark, registered businesses, 2026).
For any gas safety or electrical work that may be needed, such as moving pipes or wiring, check Gas Safe Register or NICEIC/NAPIT registration separately. Never pay a deposit upfront for grant-funded work; legitimate schemes pay the installer directly through the energy supplier (GOV.UK, energy company obligation guidance, 2026).
How to check if an insulation installer is MCS-certified
What to do if you are not eligible for a grant
Self-funding costs £1,200–£2,500 for a typical 50m² floor, with payback within 6–12 years through reduced heating bills (Energy Saving Trust, underfloor insulation cost guide, 2026). Some local authorities offer interest-free loans for energy efficiency upgrades, check your council’s website for “home energy loan” or “Green Homes Grant local scheme”.
VAT is reduced to 0% on insulation materials and installation until March 2027 for all homeowners, regardless of grant eligibility (HMRC, VAT relief on energy-saving materials, 2026). Consider DIY installation only if you have experience with building regulations, ventilation, and damp-proofing. MCS certification is not required for self-funded work, but building control approval may be needed if you alter the floor structure.
