External wall insulation, detailed properly
Insulation boards, mesh and render fixed to the outside of your walls: warmer rooms, no space lost inside, and a new face for the house. We survey free, design every detail around windows, eaves and services, and fix the price in writing before work starts.
- Guide prices online for every system, finish and type of home
- Certified systems, with the certificate number on your quote
- England, Wales, Scotland and Northern Ireland, with the local rules set out for your address
Book a free survey
Tell us where the house is and what kind it is. We reply with a time for the survey.
- Free survey for quotes
- Fixed price in writing
- System certificate with your quote
- 0% VAT on homes to March 2027
- All four UK nations
How external wall insulation is built
Every rendered EWI system is the same six layers in the same order. What changes from house to house is the board, the finish and, above all, the details at the edges.
- Starter trackFixed above the damp-proof course, so the system never sits on the ground.
- AdhesiveBonds each board to the wall, with no air gaps for cold air to move behind.
- Insulation board and anchorsEPS, mineral wool, phenolic or wood fibre, joints staggered and pinned through to the masonry.
- Basecoat and meshGlass-fibre mesh bedded in a reinforcing render, with extra patches at window corners.
- PrimerSeals the basecoat and evens out suction for the finish.
- FinishSilicone or mineral render, pebbledash, brick slips or cladding.
Systems, finishes and homes
Every service, with guide prices. Choose by board, by finish or by the kind of home.
EWI systems
Insulation boards, fixings and render systems
EWI installation
The full system: boards, fixings, mesh, render and every detail around it.
From £109 per m²
EPS insulated render
Expanded polystyrene boards: the most widely used, best-value EWI board.
From £109 per m²
Mineral wool EWI
Non-combustible stone wool slabs for blocks, close boundaries and breathable walls.
From £129 per m²
Phenolic EWI
The thinnest board for the U-value, where every millimetre counts.
From £135 per m²
Wood fibre EWI
A breathable, natural board for stone, timber-frame and older solid walls.
From £155 per m²
Brick slip EWI
Insulate the wall and keep a real brick face, bonded and pointed over the system.
From £185 per m²
Insulated cladding
Insulation behind a ventilated cladding: timber-effect, composite or fibre cement.
From £145 per m²
Insulating lime render
A breathable thermal render for heritage and stone walls where boards don't suit.
From £95 per m²Render finishes
The surface you see, and how it weathers
Silicone render finish
The most popular EWI topcoat: through-coloured, water-repellent and low-maintenance.
From £109 per m²
Mineral & silicate render
Vapour-open mineral and silicone-silicate finishes for breathable systems.
From £125 per m²
Pebbledash & dry dash EWI
A dry dash finish over insulation, so a pebbledashed house still looks pebbledashed.
From £115 per m²By type of home
How the job changes from house to house
Solid wall insulation
For pre-1930s homes with no cavity, where most heat is lost through the walls.
From £109 per m²
Non-traditional houses
System-built concrete and steel-framed homes, where EWI is often the only realistic route.
From £115 per m²
Bungalow EWI
Single-storey jobs: lighter scaffolding, quicker programmes, four elevations.
From £10,995 a house
Terraced house EWI
Mid and end terraces: neat stops at party walls, narrow passages, neighbour details.
From £8,595 a house
Semi-detached EWI
Front, side and rear: the classic 1930s semi and post-war semis.
From £13,995 a house
Detached house EWI
Four elevations, the largest wall area and the biggest saving.
From £20,495 a house
Park home insulation
Thin, lightweight insulated render systems for residential park homes.
From £6,795 a homeBlocks, landlords & housing
Rented homes, flats and housing programmes
Flats & low-rise blocks
Whole-block projects for freeholders, managing agents and residents' companies.
From £129 per m²
Social housing EWI
Street and estate programmes for councils, housing associations and their contractors.
From £99 per m²
EWI for landlords
Improve the EPC and comfort of solid-walled rental homes with tenants in place.
From £8,595 a houseRepairs & surveys
Surveys, repairs and putting failed work right
EWI repairs
Cracks, impact holes, failed sealant, algae and damaged beads put right.
From £395 a repair
Failed EWI remediation
Investigating, stripping and reinstating EWI that lets water in or causes damp.
From £135 per m²
EWI surveys
Free survey for installation quotes; paid condition reports for existing EWI.
Free survey for quotesWhich insulation board?
Four boards cover almost every job. Thickness shown is roughly what a 225mm solid brick wall needs to reach 0.30 W/m²K.
| Board | Thickness for 0.30 | Fire | Breathability | Installed price | Best for |
|---|---|---|---|---|---|
| EPS (graphite) | ≈90mm | Combustible, within system limits | Moderate | £109–£149/m² | Most houses below 11m |
| Mineral wool | ≈100–120mm | A1 / A2-s1,d0 | High | £129–£175/m² | Blocks, boundaries, noise |
| Phenolic | ≈55–65mm | Combustible, within system limits | Low | £135–£185/m² | Tight paths, eaves, reveals |
| Wood fibre | ≈120–140mm | Combustible, within system limits | Very high | £155–£215/m² | Stone, lime-built and timber walls |
Guide figures. Your quote states the board, thickness and calculated U-value for your walls. EPS vs mineral wool, explained.
Funding and VAT, nation by nation
There is no VAT on insulating a home until 31 March 2027; after that it is due to be 5%. Grants depend on where you live and your circumstances.
- England: Warm Homes: Local Grant for low-income households, where the council is taking part; GBIS closed in March 2026 and ECO4 ends on 31 December 2026.
- Scotland: Home Energy Scotland Grant and Loan, up to £7,500 grant plus £2,500 loan for solid wall insulation.
- Wales: Warm Homes Nest for low-income households.
- Northern Ireland: the Affordable Warmth Scheme, through councils.
Reviews
We only publish verified reviews from real customers, and they will appear here as jobs complete. If we have worked on your home, we would value your honest feedback.
What happens after you get in touch
Free survey
We measure the walls, check their condition, the roofline, sills, services and ventilation, and note planning and building rules.
Fixed written quote
The system, board thickness, U-value, finish, details and price, in writing, usually within a few working days.
Installation
Scaffolding, preparation, boards, mesh and render, typically two to six weeks depending on the size of the house, with photos of every hidden layer.
Sign-off
Services refitted, site cleared, building control completion and your photo record handed over.
Questions people ask
What is external wall insulation?
Insulation boards fixed to the outside of your walls, protected by a mesh-reinforced render, brick slips or cladding. It reduces heat loss without losing any room inside.
How much does external wall insulation cost?
Guide prices run from about £109 to £175 per square metre for the system and finish, plus scaffolding. For an average home that's about £8,595–£11,695 for a mid-terrace, £13,995–£19,195 for a three-bed semi and £20,495–£28,095 for a four-bed detached house, with VAT at 0% on homes.
Is the survey free?
Yes, for installation quotes, with no obligation. Condition reports on existing EWI are charged from £295.
How long does it take?
It depends on the size of the house and the weather: bungalows usually take one to two weeks on site, terraces two to three, semis three to four and detached houses four to six. Blocks of flats take longer.
Do I need planning permission?
On a house in England, often not if the finish looks similar to the existing walls. You do in conservation areas and other designated land, for flats, and for listed buildings. Wales, Scotland and Northern Ireland have their own rules, which we set out for your address.
Is building control approval needed?
Yes. In England and Wales EWI renovates a thermal element; Scotland normally needs a building warrant; Northern Ireland needs council approval. We arrange it.
Is VAT charged?
Installing insulation in a home is zero-rated for VAT until 31 March 2027, then 5%. Commercial work is standard-rated.
Can I stay at home during the work?
Yes. All the work is outside.
Areas we cover
Every county and region in England, Wales, Scotland and Northern Ireland. Remote and island work is by arrangement.
England
Wales
Scotland
Northern Ireland
Guides
All guidesHow much does external wall insulation cost in 2026?
EWI costs in 2026: guide prices per m² by system and finish, whole-house ranges for terraces, semis, detached …
Do you need planning permission for external wall insulation?
When EWI needs planning permission in England, Wales, Scotland and Northern Ireland: similar appearance, conse…
External wall insulation grants and funding in 2026
What funding is open for EWI in October 2026 across England, Wales, Scotland and Northern Ireland, and what ha…
Why external wall insulation fails, and how to avoid it
The detailing faults behind failed EWI, what the 2025 NAO and Ofgem audits found about ECO4 and GBIS installs,…