The short answer
External wall insulation typically costs around £90–£150 per square metre fitted in the UK, with straightforward jobs using basic EPS board sometimes nearer £80/m² and high-specification systems with mineral wool and silicone render passing £170/m². That rate is the installed price: it bundles the insulation boards, adhesive and fixings, the basecoat render with embedded glass-fibre mesh, the beads and trims, the topcoat finish and the labour. It is normally applied to the net wall area — the external wall surface minus windows and doors. Scaffolding, complex detailing and prep to a damp or uneven wall sit on top. Because specifications vary so much, the per-square-metre figure is best treated as a guide range.
The square-metre rate is the cleanest way to compare EWI quotes, but only if the systems being priced are the same. Here is what drives the number and what it should include.
Per m² at a glance
- Typical fitted rate£90–£150 / m²
- Basic EPS systemfrom ~£80 / m²
- High-spec system£150–£170+ / m²
- Priced onNet wall area
- IncludesBoards, render, mesh, labour
What the rate includes
A fitted EWI rate should cover the whole built-up system, not just the boards. The layers are: an insulation board mechanically fixed and bonded to the wall; a basecoat render trowelled over the boards with a glass-fibre reinforcing mesh embedded in it; beads and trims at corners, openings and the base; and a decorative topcoat — typically a mineral, polymer, silicone or brick-effect finish. The labour to set out, fix, render and finish the wall is the largest single component, which is why the rate does not simply track the cost of the insulation board.
| Board / finish | Typical rate | Note |
|---|---|---|
| EPS + mineral/polymer render | £80–£120 / m² | lowest-cost mainstream system |
| Mineral wool + silicone render | £120–£170 / m² | non-combustible, breathable |
| Phenolic + render | £130–£180 / m² | thinnest for a given U-value |
| Brick-slip / brick-effect finish | add £30–£60 / m² | premium appearance |
Indicative UK fitted rates for guidance, 2026. Sources: published installer cost guides and Energy Saving Trust.
Why the rate varies so much
Three things move the per-square-metre figure most. First, the board type and thickness: EPS is the lowest-cost option, mineral wool costs more but is non-combustible and vapour-open, and phenolic achieves a low U-value in a thinner board but at a higher price. Second, the render finish: a basic through-coloured render is cheaper than silicone, textured, ashlar or brick-effect finishes. Third, complexity: lots of corners, bay windows, narrow access or detailing around eaves and openings all slow the team and lift the effective rate.
Turning the rate into a whole-house figure
To estimate a job, multiply the net wall area by the fitted rate. A three-bed semi with roughly 100m² of net wall at £120/m² comes to about £12,000 before scaffolding and any prep. A larger detached house at 140m² on a higher-spec system at £150/m² is closer to £21,000. Because erecting and dismantling scaffolding and setting out the job are largely fixed efforts, very small areas can carry a higher effective rate, while a large continuous wall can be slightly more efficient.
When comparing quotes, get each contractor to state the board type, thickness, render system and the U-value the finished wall will reach. Two quotes at different £/m² rates may simply be different systems, and the cheaper one per metre is not necessarily better value once performance and durability are taken into account.
Where the per-metre rate sits in the total job
It helps to see the fitted rate as the core of the cost but not the whole of it. On top of the £/m² for the wall, a real job carries scaffolding (a large fixed cost on a two- or three-storey house), preliminaries such as protecting windows and moving downpipes, and any making-good to sills, soffits and the damp-proof course. If the work is grant-funded under a scheme such as ECO4 or the Great British Insulation Scheme, it must be installed to PAS 2030/2035 by a TrustMark-registered installer, which carries survey and design steps — usually built into the funded package rather than charged separately.
Finally, the 0% VAT relief on installed energy-saving materials in Great Britain, running to 31 March 2027, applies to the labour and materials of a qualifying EWI installation, which lowers the effective rate compared with standard-rated building work. Taken together, the per-square-metre figure tells you most of the story, but the scaffolding, detailing and tax treatment decide the final invoice.
A practical way to sanity-check a quoted rate is to break it into its parts. As a rough guide, the insulation board and adhesive might account for a quarter to a third of the material cost, the render system, mesh, beads and finish for the rest, and labour for the largest single share of the whole fitted rate. That is why a quote that looks cheap purely because it specifies a thinner or lower-grade board may not actually save much — the labour and render dominate and barely move. Conversely, a job with lots of detailing — many windows, bay fronts, dormers, complex corners — carries more labour per square metre even with identical materials, so its effective rate is higher. When you understand that labour and access, not the board, drive the number, the spread between £90 and £150 per square metre makes sense, and you can judge whether a quote sits where it should for the complexity of your wall.
How the rate compares with the alternatives
Putting the per-square-metre rate in context helps decide whether external insulation is the right approach at all. Internal wall insulation (IWI) is usually quoted at a lower headline rate per square metre because there is no scaffolding and no render system, but it eats into room sizes, disrupts skirtings, sockets and radiators, and has to be worked around door and window reveals room by room — so the all-in cost and disruption can be closer to EWI than the bare rate suggests. Cavity wall insulation, where a wall actually has a cavity, is far cheaper per square metre than either, but it simply does not apply to the solid walls that EWI is designed for. The reason a solid-wall home pays the EWI rate is that there is no cheaper way to insulate the wall to a comparable standard while keeping the rooms intact.
It is also worth knowing how the rate behaves at the margins. Because scaffolding, set-out and the render mixing-and-finishing process are largely fixed, a very small job — a single gable, or a short run of wall — often carries a higher effective £/m² than a whole house, since those fixed efforts are spread over fewer metres. Conversely, a large, simple, continuous elevation with few openings is where the rate is most efficient. This is why installers sometimes quote a minimum job value rather than a pure per-metre price for small areas, and why wrapping a whole property at once is usually better value per square metre than insulating one wall now and another later.
Frequently asked questions
How much does external wall insulation cost per square metre?
Typically around £90–£150 per square metre fitted in the UK. Basic EPS systems can be nearer £80/m², while high-specification mineral wool and silicone render systems can pass £170/m².
Does the per-square-metre rate include scaffolding?
Not always. Some quotes include scaffolding in the rate, others bill it separately as a fixed cost. Always confirm whether scaffolding, beads, trims and the finish coat are included before comparing rates.
Why is mineral wool more expensive than EPS per square metre?
Mineral wool boards cost more than expanded polystyrene and are heavier and slower to fix, but they are non-combustible and vapour-open, which is why they carry a higher per-square-metre rate.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific property. They are guidance, not a quotation.