External wall insulation grant
With an external wall insulation grant, the money covers boards and a weatherproof finish fixed over a solid outside wall. With most pre-1920s homes, the walls are solid rather than hollow, so filling a cavity isn't an option.
- £15,000
- What external wall insulation costs on a typical semi, if you don't get a grant
- £12,000
- The price of internal wall insulation on that same semi
- 1 in 3
- Of the heat a home loses when uninsulated, the part that goes through the walls
Which external wall insulation grant fits you
Every nation runs its own scheme. Solid wall insulation, inside or out, counts under all of them as something they can pay for when the survey shows your home needs it.
| Where you live | Scheme | What you get |
|---|---|---|
| England | Warm Homes: Local Grant | Free when your household qualifies; council projects can average up to £16,600 per home for insulation |
| Scotland | Home Energy Scotland grant and loan | £7,500 grant toward solid wall insulation, plus a £2,500 loan if you want it, for any owner |
| Scotland | Warmer Homes Scotland | Usually free, for households getting qualifying benefits |
| Wales | Warm Homes Nest | Free package if your household qualifies |
| Northern Ireland | Affordable Warmth Scheme | £10,000 cap where solid wall insulation is needed, for households earning under £23,000 |
Owners in Wales who don't qualify for Nest can turn to Green Homes Wales and ask for an interest-free loan worth £1,000 to £25,000. Enter your postcode in the grant checker to see which scheme covers where you live.
Solid wall insulation grant: is your wall solid?
Only walls without cavities qualify for a solid wall insulation grant. Which wall do you have? Three fast checks will tell you:
- Age: houses built before the 1920s are often solid walled; later ones usually have a cavity.
- Brick pattern: a solid wall has some bricks laid end-on, so short ends show among the long sides. On a cavity wall you'll see long sides only.
- Thickness: take the measurement at a door or a window. Under 260mm, a brick wall is probably solid. However thick they are, stone walls are almost always solid.
Ask an installer or surveyor to check a wall that's rendered or clad. Should it turn out that a cavity is there, cavity wall insulation costs less. The Energy Saving Trust is where these checks come from.
Internal wall insulation grant
Internal wall insulation is also covered by these schemes. Boards fit on the inner face of the outside walls, one room at a time, and every room gives up a few centimetres.
- It costs less than work on the outside.
- The outside of the house keeps its look.
- Radiators, skirting and sockets have to come off and then go back.
The way external wall insulation is fitted
The outside gets boards and a render or brick-effect finish, with scaffolding usually involved.
- You can stay at home during the work, and no room shrinks.
- Because the house looks different once it's done, planning rules may come into play.
- With scaffolding already up for a roof or windows, the price comes down.
Checks to make before anyone insulates your solid walls
Solid walls in older homes deal with moisture in a different way than modern ones do. The installer should do a few things before fixing any boards to the wall:
- mend any brickwork, pointing, gutters, downpipes or roof that is damaged;
- see how much driving rain or flooding the wall faces;
- choose paints and materials that allow the wall to breathe, and leave any vents and airbricks unblocked;
- give a guarantee lasting 25 years. A TrustMark registered installer is also required for the Warm Homes: Local Grant and Home Energy Scotland.
In October 2025 the National Audit Office reported that wall insulation work under ECO4 and also under the Great British Insulation Scheme had been poor. Homes that were affected can claim a free TrustMark audit, and every fault it finds gets repaired at no cost. For the costs and the checks shown here, the Energy Saving Trust is the source.
Questions people ask about external wall insulation grants
Can I get free external wall insulation?
You can, if your household qualifies for your nation's main scheme: the Warm Homes: Local Grant in England, Nest in Wales, Warmer Homes Scotland or the Affordable Warmth Scheme in Northern Ireland. It still depends on the survey finding your wall suitable.
Does external wall insulation need planning permission?
Talk to your council planning team before any work begins. Permission will be needed for a listed home or one inside a conservation area, since the outside of the house changes.
Is internal or external wall insulation cheaper?
The internal kind usually costs less. Inside work on a typical semi runs to about £12,000 and outside to £15,000, according to the Energy Saving Trust, before any grant.
My walls have problems now after insulation under ECO4 or GBIS. What can I do?
Free audits are being run by TrustMark for homes that got external or internal wall insulation through those schemes. Any fault the audit turns up is repaired at no charge to you.
Can solid wall insulation cause damp?
It can, where materials are wrong or repairs don't happen. A good installer repairs the brickwork, gutters and roof before starting, leaves the vents open and chooses materials an old wall can breathe through.
Get an installer survey quote
Want a survey and a price for your walls? An accredited installer can check the wall type and quote.