The Great British Insulation Scheme (GBIS) launched in April 2023 and has already helped hundreds of thousands of UK households receive free or heavily subsidised insulation measures. Running until March 2026, the scheme has a government-backed budget of £1 billion and targets homes in lower energy efficiency bands, particularly those rated EPC D, E, F, or G, to bring down heating bills and reduce carbon emissions across the country. If your home falls into the right council tax band or income bracket, you could receive insulation worth thousands of pounds at no cost to you.
What the Great British Insulation Scheme Actually Is
The Great British Insulation Scheme is a UK government initiative delivered through energy suppliers and approved installers. It sits alongside, but is distinct from, the ECO4 scheme, GBIS is specifically built to focus on single insulation measures delivered quickly and at scale, rather than the broader whole-house retrofit approach of ECO4. The scheme is administered by Ofgem and obligates the UK’s larger energy suppliers, those with 150,000 or more domestic customers, to deliver insulation upgrades to eligible households.
The scheme operates under two groups. Group A targets households in council tax bands A to D in England, A to E in Scotland, and A to C in Wales, regardless of income. Group B targets households receiving means-tested benefits such as Universal Credit, Pension Credit, or Child Tax Credit, with fewer restrictions on council tax band. This dual-group structure means the scheme reaches both lower-income households and a broader section of the general population in less energy-efficient homes.
How the Great British Insulation Scheme Works
Understanding the mechanics of GBIS helps you navigate the application process with confidence. Here is a straightforward breakdown of how the scheme functions from start to finish.
Energy suppliers are legally obligated by Ofgem to deliver a set number of insulation measures each year. They meet this obligation by funding installations in eligible homes. You do not apply directly to the government, instead, you apply through your energy supplier, a participating installer, or through a free referral service such as the government’s own Simple Energy Advice (SEA) service.
Once you express interest, a surveyor visits your property to assess which insulation measure is most suitable and what your home currently has in place. The surveyor will check your current EPC rating, the construction type of your home, and the accessibility of cavities or loft spaces. After confirming eligibility, the installer books a fitting date, the work is carried out, and your energy supplier’s obligation is reduced accordingly. The whole process from first contact to completed installation typically takes between four and twelve weeks depending on demand in your area.
The measures available under GBIS include:
- Cavity wall insulation, injecting insulating material into the gap between your inner and outer walls
- Loft insulation, laying mineral wool or blown fibre between and over the joists in your roof space
- Solid wall insulation, internal or external insulation boards for homes without a cavity
- Underfloor insulation, rigid boards or blown insulation beneath suspended timber floors
- Flat roof insulation, for properties with flat roof sections
- Room-in-roof insulation, for converted loft spaces with sloped ceilings
- Pitched roof insulation, insulation at rafter level for certain property types
Eligibility for the Great British Insulation Scheme in 2026
Eligibility is the first hurdle, and it is worth checking carefully before investing time in applications. The scheme has specific criteria tied to your home’s EPC rating, your council tax band, and in some cases your household income.
Your home must have an EPC rating of D or below to qualify under the general (Group A) route. Homes already rated A, B, or C are considered sufficiently well insulated and do not qualify. For Group B applicants receiving means-tested benefits, the EPC requirement is slightly more flexible, but the home must still have identifiable scope for improvement via one of the eligible insulation measures.
Key eligibility criteria include:
- EPC rating of D, E, F, or G (Group A) or any rating if on qualifying benefits (Group B)
- Council tax band A to D in England (or A to E in Scotland / A to C in Wales) for Group A
- Owner-occupier or private tenant status (landlords can apply in some cases with tenant consent)
- The property must be a domestic dwelling, commercial properties do not qualify
- The identified insulation measure must not already be installed to an adequate standard
Tenants in privately rented properties can also benefit, but the landlord must typically give consent and may be required to contribute a co-payment toward the cost of the measure, particularly for more expensive installations like solid wall insulation.
How Much Does the Great British Insulation Scheme Cost in 2026
For eligible households, GBIS can cover the full cost of insulation installation. However, the level of subsidy varies depending on which group you fall into, the type of measure being installed, and the property type. Some households, particularly landlords or those in Group A with slightly higher incomes, may be asked to contribute a co-payment.
| Insulation Type | Typical Market Cost | GBIS Group A Cost to You | GBIS Group B Cost to You |
|---|---|---|---|
| Loft Insulation (semi-detached) | £300 – £600 | £0 – £50 | £0 |
| Cavity Wall Insulation (semi-detached) | £500 – £1,500 | £0 – £200 | £0 |
| External Solid Wall Insulation (mid-terrace) | £8,000 – £22,000 | £500 – £3,000 | £0 – £500 |
| Internal Solid Wall Insulation (semi-detached) | £5,500 – £12,000 | £300 – £2,000 | £0 – £300 |
| Underfloor Insulation (suspended timber floor) | £800 – £2,000 | £0 – £200 | £0 |
| Room-in-Roof Insulation | £1,500 – £3,500 | £0 – £400 | £0 |
These figures reflect 2026 market rates and typical GBIS contribution levels. The actual cost to you will be confirmed during the survey and assessment stage. Always request a written breakdown before any work begins so you know exactly what, if anything, you will be expected to pay.
For context, loft insulation on a typical semi-detached home can save approximately £150 per year on heating bills, while cavity wall insulation saves around £195 per year according to the Energy Saving Trust’s 2024 figures. Solid wall insulation offers larger savings, typically £280 to £475 per year depending on property size and heating system.
Benefits of the Great British Insulation Scheme
The advantages of participating in GBIS extend well beyond the immediate financial saving on installation costs. Here is what properly installed insulation delivers in real terms.
Lower energy bills: A well-insulated home retains heat more effectively, meaning your boiler runs for shorter periods. Households with adequate loft and wall insulation can expect to reduce their space heating demand by 20% to 40%, translating to annual bill savings of £150 to £500 depending on home size and current energy performance.
Improved EPC rating: Most GBIS-funded measures will improve your home’s EPC by at least one band. Moving from an EPC E to a D or C is significant, it increases the property’s market value, reduces mortgage risk premiums on some green mortgage products, and helps meet forthcoming minimum energy efficiency standards for rental properties.
Reduced carbon footprint: The average UK home produces around 2.7 tonnes of CO2 per year from space heating alone. Effective insulation can cut that figure by 0.5 to 1.2 tonnes annually, contributing meaningfully to the UK’s net zero targets.
Greater thermal comfort: Cold walls and draughty floors cause more than high bills, they contribute to damp, condensation, and respiratory health problems. Insulation stabilises internal temperatures, reduces cold spots, and can significantly improve air quality and comfort throughout the winter months.
Increased property value: Research by Nationwide Building Society found that upgrading a home from an EPC rating of G to a D adds approximately 6% to property value on average. Energy-efficient homes are increasingly in demand from buyers who understand the long-term cost implications of poor insulation.
How to Choose the Right Insulation Measure Under GBIS
Not every insulation type is suitable for every home, and GBIS only funds one measure per property (in most cases). Getting the right measure identified is therefore critical. Here is a practical decision framework.
Start by understanding your home’s construction. Homes built before 1920 are typically solid-walled (no cavity), making cavity wall insulation irrelevant for them. Homes built between approximately 1920 and 1995 are most likely to have cavity walls and therefore are the strongest candidates for cavity wall insulation if that cavity is currently unfilled. Post-1995 homes are often already insulated at build stage but may have inadequate loft insulation top-ups.
Ask yourself these questions to guide the process:
- Do you have a loft? If yes, is there less than 100mm of insulation currently? If so, loft insulation is likely your best starting point, it is cheap to install, highly effective, and almost always fully funded under GBIS.
- Do you have cavity walls with unfilled cavities? A borescope survey (offered free during the GBIS assessment) can confirm this in minutes. Cavity wall insulation typically offers the second-best cost-to-benefit ratio.
- Do you have solid walls? If so, the choice between internal and external insulation depends on whether you want to retain your external appearance, whether you have planning restrictions (such as in a conservation area), and how much internal space you can afford to lose (internal insulation typically reduces room width by 80–110mm per treated wall).
- Do you have a suspended timber floor with accessible underfloor space? If yes, underfloor insulation is worth prioritising before tackling walls, as heat loss through uninsulated floors can be 10–15% of a home’s total heat loss.
During the GBIS survey, the assessor will recommend the measure that delivers the greatest improvement to your EPC. However, you are entitled to ask questions and understand the reasoning. If you disagree with the recommendation or want a second opinion, you can request a reassessment or contact a different participating supplier.
The Great British Insulation Scheme Installation Process
Knowing what to expect on the day of installation reduces stress and helps you prepare your home properly. Here is a step-by-step guide to what happens.
Step 1, Initial Assessment
A surveyor visits your home, typically for 30 to 90 minutes. They inspect the loft, external walls, floor type, and any existing insulation. They confirm EPC eligibility and identify the recommended measure. This visit is free of charge.
Step 2, Confirmation and Scheduling
You receive written confirmation of the measure to be installed, the cost to you (if any), and an estimated installation date. Read this carefully before signing anything. Installation is usually booked 2 to 8 weeks after survey completion.
Step 3, Preparation
For loft insulation: clear the loft of stored items and ensure the hatch is accessible. For cavity wall insulation: move furniture away from external walls and clear the exterior of shrubs or garden structures. For internal solid wall insulation: expect significant disruption, rooms will need to be vacated, skirting boards and architraves removed, and electrical sockets temporarily repositioned.
Step 4, Installation Day
Loft insulation typically takes 2 to 4 hours for a standard semi-detached home. Cavity wall insulation takes 4 to 6 hours. Internal solid wall insulation can take several days per room. External solid wall insulation is a multi-day project, often requiring scaffolding. The installer must be registered with TrustMark and use materials meeting current British Standards.
Step 5, Post-Installation Check
Reputable installers will conduct a post-installation inspection and provide you with a completion certificate. This document is important, keep it safe as it proves the work was done to the required standard and may be needed when selling your home or applying for further grants.
Step 6, Updated EPC
Your installer or energy supplier should arrange an updated EPC to reflect the improvement. This is often done automatically as part of the GBIS process, but it is worth confirming. Your new EPC rating is lodged on the national register and will be visible to future buyers or tenants.
Grants and Funding for the Great British Insulation Scheme
GBIS is itself the primary grant mechanism for insulation in 2026, but it does not exist in isolation. Understanding how it interacts with other available funding can help you maximise the support available to your household.
| Scheme | Who It Targets | Insulation Covered | Maximum Support |
|---|---|---|---|
| Great British Insulation Scheme (GBIS) | EPC D–G, council tax bands A–D, or on benefits | Single insulation measure | Full cost in most cases |
| ECO4 | Low-income households on qualifying benefits | Multiple insulation and heating measures | Full cost of whole-house package |
| Home Upgrade Grant (HUG2) | Low-income households off the gas grid | Insulation plus low-carbon heating | Up to £30,000 per property |
| Local Authority Flexibility (LAFlex) | Households in fuel poverty at LA discretion | Various insulation types | Varies by local authority |
In practice, GBIS and ECO4 cannot fund the same measure on the same property, but they can fund different measures. A household might receive cavity wall insulation under GBIS and then access ECO4 for a heat pump or heating controls upgrade. The key is to apply for GBIS first as it is the simpler and faster route, then explore ECO4 for additional measures.
Some local authorities also offer their own top-up funding, particularly in areas with high concentrations of solid-walled Victorian terraces. Check your council’s website under “home energy efficiency” or “fuel poverty”, a number of councils in the North West, Yorkshire, and Wales have active local schemes that can bridge the gap on co-payments for solid wall insulation.
Common Problems and How to Avoid Them
GBIS has not been without its difficulties. Understanding the most common issues means you can take steps to protect yourself and ensure the work is done properly.
Cavity wall insulation in unsuitable properties is the single most reported problem. Some homes, particularly those with narrow cavities, exposed or coastal locations, or existing damp issues, are not suitable for cavity wall insulation. If insulation is installed inappropriately, it can trap moisture, leading to damp penetration and structural damage. Always insist on a proper wall tie and moisture survey before cavity wall insulation proceeds. If the installer is not offering this, ask why not.
Thin or uneven loft insulation is another issue. Some installers lay the minimum depth to claim the measure as complete. Current best practice recommends a minimum of 270mm of mineral wool loft insulation, 100mm between the joists and 170mm laid perpendicular over the top. Check the depth yourself using a ruler after installation.
Inadequate ventilation after insulation can cause condensation problems, particularly in solid wall insulation projects. Insulating walls without addressing ventilation can push moisture into the remaining breathable elements of a solid wall structure. A good installer will assess ventilation as part of the survey and recommend mechanical ventilation or improved air bricks where needed.
Unregistered installers remain a concern. GBIS requires all installers to be TrustMark registered and to hold relevant PAS 2030 certification. Ask your installer to confirm their TrustMark registration number before work begins and verify it on the TrustMark website. Work completed by unregistered installers may not be covered by the guarantee requirements of the scheme.
Post-installation guarantees are mandatory under GBIS. Cavity wall insulation must be guaranteed for 25 years, and loft insulation for 10 years, under the Cavity Insulation Guarantee Agency (CIGA) and Solid Wall Insulation Guarantee Agency (SWIGA) schemes respectively. Ensure you receive your guarantee certificate and register it promptly.
Maintenance of Insulation Installed Under GBIS
Insulation is generally a low-maintenance building upgrade, but there are sensible steps to take to protect your investment and ensure it performs as expected over its lifetime.
For loft insulation, avoid compressing it, compressed insulation loses its thermal resistance rapidly. If you use your loft for storage, install a raised loft boarding system that sits above the insulation rather than on top of it. Check annually that roof tiles are intact and that no water ingress is compromising the insulation. Wet mineral wool loses virtually all of its insulating value and must be replaced.
For cavity wall insulation, the main maintenance consideration is ensuring that render, pointing, or cladding on your external walls remains intact. If water penetrates the outer leaf of a cavity wall, it can saturate the insulation and bridge the cavity. Have your external walls inspected every 5 to 7 years and repoint or re-render as needed.
For solid wall insulation, internal insulation boards should be checked for any signs of condensation at junctions (where insulated wall meets uninsulated floor or ceiling). External insulation systems require their render or cladding coat to be maintained, surface cracks should be filled and painted promptly to prevent water ingress behind the insulation board.
How to Apply for the Great British Insulation Scheme
Applying for GBIS is more straightforward than many homeowners expect. Here is the practical path to follow in 2026.
The fastest route is through the government’s Simple Energy Advice service at simpleenergyadvice.org.uk (or via the phone line 0800 444 202, which is free to call). The service checks your eligibility, identifies appropriate measures, and refers you to participating energy suppliers and installers in your area.
Alternatively, contact your current energy supplier directly. All major suppliers, including British Gas, EDF, E.ON, Octopus Energy, OVO, and Scottish Power, participate in GBIS and have dedicated home improvement teams. Have your most recent energy bill, your EPC certificate (or the property’s EPC reference number), and your council tax band reference to hand before you call.
You can also be referred to GBIS through your local authority, your GP surgery (in the case of health-related fuel poverty referrals), or through a registered community energy organisation. Wherever the referral comes from, the process and entitlements are the same.
There is no cost and no obligation at the assessment stage. You are under no pressure to proceed if, after the survey, you are not satisfied with the proposed measure or the installer. You can request a second opinion or a different approved installer at no cost.
The scheme’s current funding runs until March 2026, and while an extension or successor programme is anticipated given the government’s ongoing net zero commitments, nothing is confirmed beyond that date. If your home is eligible, applying sooner rather than later ensures you benefit from current funding levels before any programme changes take effect.
