Underfloor insulation grants

What underfloor insulation is — and which floor you have

Underfloor insulation reduces the heat that escapes downwards through your ground floor. Before you look at grants, you need to know which type of floor you have, because it changes both the cost and whether a scheme will touch it.

Most pre-1950s UK homes have a suspended timber floor: floorboards laid over joists, with a ventilated air gap (a void) underneath and air bricks in the outside walls. This is the floor that grants and installers target, because it can usually be insulated from below by fitting mineral wool or rigid board between the joists — either by lifting a few boards or by working in the void where there is a cellar or crawl space. It is relatively contained work.

Newer homes (broadly post-1960s) tend to have a solid concrete floor laid directly on the ground. Insulating a solid floor means either laying rigid insulation and a new floor surface on top — which raises the floor level and affects skirting boards, door heights and thresholds — or digging out and re-laying the whole floor. It is a much bigger, more disruptive and more expensive job, and it is far less commonly funded as a standalone measure. If you have a solid floor, treat underfloor insulation as a major renovation decision rather than a quick grant-funded upgrade, and prioritise other measures first.

The figures on this page are for suspended timber floors. According to the Energy Saving Trust, insulating a suspended timber floor typically costs between £1,400 and £2,500 before any grant. That range reflects floor size, how easy the void is to access, and whether draught-proofing around the edges is included. You can see how it sits against other measures on our insulation grant cost guide.

Which grants fund underfloor insulation

Underfloor insulation is eligible under most of the main UK schemes, but it is rarely the headline measure. It is usually funded as part of a fabric-first, whole-house upgrade — insulation grants prioritise the biggest heat-loss measures first (loft and walls), and floors come in alongside them. The scheme you use depends on which nation you live in, so start by confirming the right one for your home on our grants and funding hub, then run the eligibility checker.

ECO4 (England, Scotland and Wales)

The Energy Company Obligation phase 4 (ECO4) is open and has been extended to 31 December 2026. It is delivered by obligated energy suppliers on a fabric-first basis, so underfloor insulation can be included where a retrofit assessment identifies it as part of the recommended package. You do not apply to Ofgem — you go through an obligated supplier or an accredited installer, or via your council under the ECO4 Flex (LA Flex) route. Suppliers may stop taking new referrals before the end date, so it is worth acting while the scheme is open. ECO4 covers Great Britain only — not Northern Ireland. Full detail is on our ECO4 page.

To qualify, an owner-occupier generally needs an EPC of D–G plus a qualifying means-tested benefit (Universal Credit, Pension Guarantee Credit, income-based JSA/ESA, Income Support, Housing Benefit, Working or Child Tax Credit, and others). If you are not on benefits, the ECO4 Flex route lets your council refer low-income households under its published Statement of Intent — see insulation grants if you are not on benefits.

Warm Homes: Local Grant (England only)

The Warm Homes: Local Grant (WH:LG) is open in England, delivered by your local council at no cost to the occupant, running from April 2025 to around 31 March 2028. It funds wall, loft and underfloor insulation, heating controls, air source heat pumps and solar as part of a wider upgrade. To be eligible your home must be EPC D–G and you must meet one of: a household income usually at or below £36,000 a year; a qualifying means-tested benefit; or an eligible low-income postcode. It covers both on-gas and off-gas homes. The gov.uk apply page states no maximum grant; some homes are reported to receive up to around £30,000 (check current gov.uk guidance), but availability is genuinely council-by-council. See our England grants page.

Home Energy Scotland Grant (Scotland)

In Scotland the main route is the Home Energy Scotland (HES) Grant and Loan, accessed through a single gateway. The HES Grant has no benefits test and pays 75% of an energy-efficiency measure's cost, subject to per-measure caps. For floor insulation the combined cap is £2,000 — the same cap that applies to loft and cavity wall insulation. You must own and live in the home, and the measure has to be recommended in an EPC or home energy report. Warmer Homes Scotland and council-run Area Based Schemes are separate routes for lower-income households. There is no HES benefits gate, which makes Scotland one of the more accessible nations for able-to-pay owners — details on our Scotland grants page.

Warm Homes Nest (Wales)

In Wales, the Welsh Government's Warm Homes Nest scheme funds insulation and heating for eligible households, and ECO4 also applies. Nest's exact eligibility and any measure caps change, so confirm the current figures against nest.gov.wales before relying on a number — see our Wales grants page. Nest is a fuel-poverty scheme, so eligibility is means-tested.

Northern Ireland

ECO4 does not operate in Northern Ireland. Funding there runs through the Affordable Warmth Scheme (via the NI Housing Executive) and NISEP, both with their own income thresholds. Underfloor insulation may be included within a wider package where a scheme applies.

Grant comparison at a glance

Never mix a scheme with the wrong nation — England's Warm Homes: Local Grant does not exist in Scotland, and HES does not exist in England. Confirm your nation first.

Is underfloor insulation ever genuinely free?

Sometimes, but not always, and it is honest to say so. Lower-cost measures under ECO4 or WH:LG are often fully funded, but a contribution may be requested — most commonly on high-cost measures such as solid wall insulation rather than a straightforward suspended timber floor. The HES Grant explicitly funds 75%, not 100%, so in Scotland you should expect to pay the remaining quarter up to the £2,000 cap. We explain the reality behind the "free" headline on our free insulation grants page.

Even without a grant, installing qualifying insulation in Great Britain has been at 0% VAT under the Energy-Saving Materials relief, which is a real saving for able-to-pay homeowners. Confirm the current rate and any end date against HMRC VAT Notice 708/6, as Northern Ireland treatment can differ, and treat this as general information rather than tax advice.

Quality, standards and avoiding scams

Grant-funded underfloor insulation must be installed to recognised standards. Look for a TrustMark-registered installer working to PAS 2035 (retrofit) and PAS 2030 (installation). A compliant job starts with a retrofit assessment and a Retrofit Coordinator — if an installer skips the assessment and simply tries to sell you a measure, treat that as a red flag.

Be especially wary of "free insulation grant" cold calls, texts and doorstep sellers. Real schemes are applied for through gov.uk, Home Energy Scotland, your council, or an accredited installer — never through an unsolicited caller. Never pay upfront and never let work begin before you have written grant approval. If you rent, private tenants can still access funding with the owner's permission — see insulation grants for private tenants.

How to apply

Underfloor insulation is best pursued as part of a whole-house upgrade rather than in isolation. A sensible order is:

• Check your EPC first — most schemes need a D–G rating.
• Confirm the right scheme for your nation on our funding hub.
• Run the eligibility checker to see which routes you qualify for.
• Book a retrofit assessment through the scheme's official channel so a coordinator can recommend the full package — which may combine floor insulation with loft or wall measures.
• Only start work once you have written approval.

Our step-by-step how to apply guide walks through each stage. If you would like us to point you to the right route, use the enquiry form on our get a quote page — we install nothing and run no scheme; applying to the real schemes through official channels is always free. You may also want to compare floors against the two most-funded measures, loft insulation grants and solid wall insulation grants, or read the common questions on our FAQs page.

Authoritative sources

Always verify figures and eligibility against the official pages before applying:

• Warm Homes: Local Grant (gov.uk)
• Home Energy Scotland Grant and Loan (mygov.scot)
• Energy Saving Trust — measure costs and savings