Cost guides › External wall insulation
United Kingdom
External wall insulation cost
Insulating 150 m² of solid wall from outside typically costs £26,000 with 0% VAT, with most quotes between £20,300 and £33,800. That covers scaffolding for two months, 140 mm insulation boards fixed to the walls, starter and corner trims, sealing under the eaves and a silicone render finish. Thinner 100 mm boards bring it to about £23,400; non-combustible mineral wool boards are around £30,500.
Most homeowners pay
0% VAT on installing energy-saving materials (heat pumps, insulation, solar) until 31 March 2027
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mid-range, typicalCost by region
| Location | Basic | Mid-range | Premium |
|---|---|---|---|
| London | £24,200 | £26,800 | £31,300 |
| Scotland | £23,500 | £26,100 | £30,700 |
| South East | £23,400 | £26,000 | £30,500 |
| East | £23,300 | £25,800 | £30,400 |
| North West | £23,200 | £25,800 | £30,300 |
| East Midlands | £23,100 | £25,700 | £30,200 |
| South West | £23,100 | £25,700 | £30,200 |
| Wales | £23,100 | £25,700 | £30,200 |
| West Midlands | £23,200 | £25,700 | £30,200 |
| North East | £23,100 | £25,600 | £30,100 |
Show all regions
| Yorkshire and The Humber | £23,000 | £25,600 | £30,100 |
What's included
Mid-range
- Scaffolding erected around the house, hired for two months and taken down
- 140 mm EPS insulation boards adhered and mechanically fixed to the walls
- An aluminium starter track with drip at the base of the insulation
- Mesh-reinforced corner beads on the building corners and window reveals
- A sealed top closure under the eaves
- Reinforced base coat, primer and two coats of siloxane render finish
What affects the cost
Wall area and house shape
The price scales mostly with wall area, but every window, door, corner and bay adds trims and detailing time. A plain end-terrace wall is cheaper per square metre than a detached house with bays and many openings.
Insulation material and thickness
EPS boards are the cheapest. Thicker boards improve the U-value for a modest extra cost, while mineral wool is non-combustible and vapour-open, which suits older solid walls, but costs more.
Moving fittings on the wall
Downpipes, gas meter boxes, satellite dishes, outside lights and flues all have to be taken off and refitted further out. Window sills usually need extending and roof overhangs may be too shallow to cover the new wall thickness; these are not included here.
Condition of the existing wall
Loose render, damp or cracked brickwork must be repaired before the insulation goes on. A survey should check for rising or penetrating damp, which insulation will not cure.
Scaffolding and access
Scaffolding is needed on every insulated elevation. Terraced houses with rear access only through the house, or walls over a neighbour's land, add cost and time.
Finish
Coloured siloxane or silicone render is standard. Brick-effect slips or finishes chosen to match neighbouring houses cost considerably more, and may be required in some streets.
How to save
- Book before 31 March 2027 while installing wall insulation is charged at 0% VAT.
- Combine the work with roof, window or solar jobs to share the scaffolding cost.
- Insulate the worst elevations first, usually the exposed gable end and north-facing walls, if the budget does not stretch to the whole house.
- Check whether your household qualifies for Warm Homes Plan grants or low-interest loans before you pay in full.
Grants, tax and rules
0% VAT until 31 March 2027
Installing insulation is charged at 0% VAT until 31 March 2027, and our figures use that rate.
Warm Homes Plan
Published in January 2026, it commits £15bn to 2030, including grants for low-income households and low- or zero-interest loans that are being phased in.
Frequently asked questions
How much does external wall insulation cost in the UK?
For 150 m² of wall, expect around £26,000 with 0% VAT, including scaffolding and a render finish. Thinner boards bring it to about £23,400; mineral wool is around £30,500.
How do I know if my house has solid walls?
Most houses built before the 1920s have solid walls. In exposed brickwork, a solid wall usually shows some bricks laid end-on (headers) in the pattern, and walls are often around 22 cm thick at a window or door opening. Cavity walls show only long faces of bricks.
Is external or internal wall insulation better?
External insulation keeps all your room space, covers the whole wall without cold bridges at floors and partitions, and can be done while you live in the house. Internal insulation is cheaper per wall and needs no scaffolding but loses floor area and means redecorating every room.
Do I need planning permission for external wall insulation?
It changes the look of the house, so planning permission may be needed, particularly on the front elevation, in conservation areas or on listed buildings. Check with your local council before you commit.
How long does external wall insulation take?
A typical house takes three to six weeks including scaffolding, which is why our estimate includes two months of scaffold hire. Render cannot be applied in frost or heavy rain, so winter jobs can overrun.
How this estimate is calculated
Work hours: 201.4 · Labour: £6,871 · Materials: £19,108
Sources: ONS Annual Survey of Hours and Earnings, tables 14 and 15; Regione Toscana, Prezzario dei Lavori 2026 (CC BY 4.0); ECB exchange rates.