How much does external wall insulation cost in the UK? (2026)
Verified UK external wall insulation prices for 2026 per square metre and by property size, what the job actually involves, the grants that can cut the cost, and the scope gaps that catch people out.
External wall insulation in the UK in 2026 costs £85 to £130 per square metre, which puts a typical three-bedroom semi at around £10,000. It is a five-figure job that wraps a solid-wall home in insulation and a fresh render finish in one go. The figure that changes everything is whether you qualify for a grant, which can cover a large share of the cost.
Quick answer
UK external wall insulation in 2026: £85-£130 per m², around £10,000 for a standard three-bed semi, and £8,000-£25,000 across property sizes. Grants (Great British Insulation Scheme, Warm Homes: Local Grant) can fund part or all of it for eligible homes. Best suited to solid-wall properties with no cavity.
How to read this guide#
Two kinds of figures appear below:
- Headline price ranges (per m² and by property size): cross-referenced against the Federation of Master Builders' UK 2026 EWI guide. Source listed at the bottom.
- Practical guidance (what the job involves, grants, what is excluded): standard UK practice, for context rather than figure-by-figure verification.
Headline ranges (verified)#
External wall insulation, UK 2026:
| Measure | Typical cost |
|---|---|
| Per square metre | £85 – £130 |
| Standard 3-bed semi (average) | ~£10,000 |
| Small terraced house | from ~£8,000 |
| Large detached house | up to ~£25,000 |
The per-m² rate is the reliable benchmark; property totals depend on the wall area, the finish, and access. Scaffolding (around £625 a week) and any scaffold licence for a public footpath are usually inside the quote, but confirm it.
Practical guidance (industry standard)#
Is your home even right for EWI?#
EWI is designed for solid-wall homes, typically built before about 1920, where there is no cavity to fill. If your home has a cavity, the far cheaper cavity wall insulation is almost always the better first step. Spending £10,000 on EWI when £1,000 of cavity insulation would do most of the job is the single most expensive mistake here.
Check for a grant before paying#
This is the check that can save thousands. The main 2026 routes are:
- Great British Insulation Scheme and Warm Homes: Local Grant, which can fund part or all of the cost for eligible households, usually based on EPC band, qualifying benefits, or council area.
- The older ECO4 scheme closed to new applications in March 2026.
Check eligibility on GOV.UK before commissioning a private quote. A grant-funded install runs through approved installers, so the route changes who you get quotes from.
What the job involves#
A proper EWI install is more than sticking boards on a wall:
- Scaffolding around the property.
- Insulation boards (EPS, mineral wool, or phenolic) fixed and pinned to the wall, thickness chosen for the target U-value.
- Reinforcing mesh and basecoat over the boards.
- Weatherproof finish: silicone or mineral render, or a brick-effect or cladding finish at higher cost.
- Detailing around windows, doors, eaves, verges, and the damp-proof course, plus removing and refitting downpipes, sills, and vents.
The render finish overlaps with standard rendering work, but EWI render sits over insulation, not bare wall.
What affects the price#
- Finish. Basic silicone render is cheapest; brick-effect and cladding cost far more.
- Board thickness. Thicker boards hit better U-values but cost more and need deeper reveals.
- Access. Three storeys, restricted streets, or a scaffold licence add cost.
- Detailing. Reveals, eaves extensions, and moving pipework and meters all add labour.
What is often excluded#
- Reveal and sill detailing around windows and doors, where boards meet the frames.
- Eaves and verge extensions needed to cover the thicker wall.
- Moving downpipes, vents, meter boxes, and external taps.
- Making good to paths, drives, and planting after scaffolding.
- Damp or repair work to the wall before insulating, which must be sound first.
Red flags in an EWI quote#
- No board thickness or U-value. You cannot tell what performance you are buying.
- No render type named. Silicone, mineral, and brick-effect differ hugely in price.
- Reveals and detailing not itemised. The most common place for a quote to look cheap and then climb.
- EWI proposed on a cavity-wall home without explaining why cavity insulation is not the cheaper option.
- No mention of grants where the household may well qualify.
Comparing your quote#
If you have an EWI quote, check the board thickness, the render finish, and that reveals and detailing are itemised, and confirm whether a grant applies. The faster way is to paste or upload your quote into Check the Quote: we check every line against current UK rates for your postcode, flag anything above the fair range, and tell you what is missing from the scope. Your first check is free.
Got a quote you want checked?
Paste any UK contractor quote and Check the Quote compares every line item against current market rates, flags missing scope, and runs a Companies House check on the contractor. Free on your first project.
Frequently asked questions
- How much does external wall insulation cost in the UK in 2026?
- External wall insulation (EWI) costs roughly £85-£130 per square metre, making a standard three-bedroom semi-detached house around £10,000 on average (FMB, 2026). Across property sizes the range is broad, from about £8,000 for a small terrace to £25,000 for a large detached house, depending on wall area, finish, and access.
- Is external wall insulation worth it?
- For a solid-wall home (typically pre-1920s, with no cavity to fill), EWI is one of the most effective ways to cut heat loss and lower bills, and it refreshes the exterior at the same time. It is a major job with a five-figure cost, so the payback is measured in years. For a cavity-wall home, cavity wall insulation is far cheaper and usually the better first step.
- What grants are available for external wall insulation?
- The main 2026 routes are the Great British Insulation Scheme and the Warm Homes: Local Grant, which can fund part or all of the cost for eligible households (lower EPC bands, qualifying benefits, or certain council areas). The ECO4 scheme closed to new applications in March 2026. Check eligibility on GOV.UK before paying for a private quote, as a grant can cover a large share of the cost.
- What does an external wall insulation quote include?
- A full EWI quote should cover scaffolding, insulation boards fixed to the wall, a reinforcing mesh and basecoat, a weatherproof render or cladding finish, and all the detailing around windows, doors, eaves, and the damp-proof course. Reveals, sills, downpipe removal and refit, and making good are where quotes most often differ, so check they are itemised.
- Why is one EWI quote so much higher than another?
- Usually the finish and the detailing. A basic silicone render over thin boards costs far less than a brick-effect or thicker board with full reveal and eaves detailing. Access matters too: a three-storey house or restricted street needs more scaffolding. A quote that does not state board thickness, render type, and how reveals are handled cannot be compared like-for-like.