External wall insulation (EWI) is one of the most effective ways to make a solid-wall home warmer and cheaper to heat – but it is also one of the bigger home improvement investments. In this guide we break down what external wall insulation really costs in 2026: the price per m², typical costs by house type, how the budget splits between materials, labour and scaffolding, and how to keep the total down.
How much does external wall insulation cost?
In 2026, external wall insulation in the UK typically costs £100-£180 per m² fully installed, with most projects landing around £120-£150 per m². For a typical 3-bed semi-detached house, expect £10,000-£18,000 including materials, labour and scaffolding. Materials alone usually cost £35-£55 per m² for an EPS system with render.
External wall insulation costs at a glance
| Cost item | Typical 2026 price |
|---|---|
| Fully installed EWI (per m²) | £100-£180 |
| Materials only – EPS system (per m², ex. VAT) | £35-£55 |
| Materials only – mineral wool system (per m², ex. VAT) | £50-£80 |
| Labour (per m²) | £60-£100 |
| Scaffolding (typical house) | £1,000-£3,500 |
| Mid-terrace house | £6,000-£11,000 |
| 3-bed semi-detached house | £10,000-£18,000 |
| Detached house | £15,000-£30,000 |
Prices are typical UK ranges for 2026 and vary with wall area, access, wall condition, insulation type and finish. London and the South East are usually at the upper end of each range.
External wall insulation cost per m²
Most installers price EWI per square metre of wall area, measured after deducting windows and doors. A fully installed system usually costs £100-£180 per m². That figure normally covers insulation boards, adhesive, fixings, mesh, basecoat, primer, render and labour. Scaffolding is often quoted separately – always check your quote.
Cost per m² by insulation type
White EPS + silicone render
£100-£140 per m²
The most common choice for houses and the lowest-cost system.
Graphite EPS + silicone render
£110-£150 per m²
Better thermal performance – thinner boards for the same U-value.
Mineral wool + render
£130-£180 per m²
Non-combustible and breathable, but heavier and slower to install.
EPS insulation boards are the default for most domestic projects. Mineral wool insulation costs more, but is chosen where fire performance or breathability matters – for example on attached properties, taller buildings or older walls prone to moisture.
External wall insulation cost by property type
The biggest factor in the total price is your wall area. A detached house has four exposed elevations, a semi-detached three, and a mid-terrace usually only the front and rear.
| Property type | Typical wall area (net) | Materials only (ex. VAT) | Fully installed incl. scaffolding |
|---|---|---|---|
| Mid-terrace | 40-60 m² | £1,400-£3,300 | £6,000-£11,000 |
| End-terrace | 70-90 m² | £2,500-£5,000 | £8,000-£14,000 |
| Detached bungalow | 70-100 m² | £2,500-£5,500 | £9,000-£16,000 |
| 3-bed semi-detached | 80-110 m² | £2,800-£6,000 | £10,000-£18,000 |
| Detached house | 120-180 m² | £4,200-£9,900 | £15,000-£30,000 |
Bedrooms alone do not tell you the price – a large, extended semi can have more wall area than a small detached house. Measure your walls (or use the measurements from your survey) and run them through our EWI cost calculator for exact material quantities.
Price your project in 2 minutes
Enter your wall area and house type – get a full list of EWI materials with quantities and a NET price, ready to add to your basket.
Use the EWI cost calculatorWhat makes up the cost of external wall insulation?
Materials
A complete EWI system is made of several layers, all of which need to be compatible:
| Component | What it does | Typical cost per m² (ex. VAT) |
|---|---|---|
| Insulation boards (EPS, graphite EPS or mineral wool) | The insulating layer | £10-£35 |
| Adhesive | Bonds boards to the wall | £3-£6 |
| Mechanical fixings | Secure boards to the substrate | £2-£4 |
| Fibreglass mesh + basecoat | Reinforcing layer, prevents cracking | £5-£9 |
| Primer | Prepares the basecoat for render | £1-£2 |
| Render finish (silicone, acrylic, mineral) | Weatherproof, decorative top coat | £6-£14 |
| Profiles and beads | Starter tracks, corners, window and stop beads | £2-£5 |
You can buy every layer of the system from our external wall insulation range – insulation board adhesives, fibreglass mesh, primers and silicone renders.
Labour
Labour is usually the largest part of an installed price, typically £60-£100 per m². EWI is a multi-stage process – preparation, boarding, fixing, meshing, basecoat, primer and render – and every stage needs drying time. Window and door reveals, corners and complex detailing add time and cost.
Scaffolding
Scaffolding is needed on almost every EWI job. For a small terrace or a single elevation expect around £800-£1,200; for a full semi-detached house with three elevations around £1,400-£2,000; and for larger detached properties £3,000 or more. Costs rise with height, difficult access and longer hire periods.
What affects the final cost?
- Wall area – the more m² you insulate, the higher the total, although the price per m² usually drops on larger jobs.
- Insulation type and thickness – mineral wool and thicker boards cost more. Most UK solid-wall homes need around 90-100 mm of EPS to meet current U-value targets. See our EWI thickness guide.
- Wall condition – damp, loose render or damaged brickwork must be repaired before insulation goes on.
- Detailing – the number of windows, doors, corners and external fittings.
- Render finish – silicone render costs more than acrylic, but is self-cleaning and lasts longer. Brick slips cost significantly more than render.
- Location and access – London and the South East are usually at the upper end of the range; restricted access increases scaffolding and labour time.
Hidden costs to budget for
- Extending or replacing window sills
- Moving downpipes, gas meters, satellite dishes and external lights
- Extending boiler flues and vents
- Extending roof eaves or verges if the insulation is thick
- Repairs to the existing wall surface
- Skip hire and waste removal
Tip: add a 10% contingency to your budget to cover unexpected work.
How to budget for external wall insulation – step by step
1. Measure your wall area
Multiply the length of each wall by its height, then subtract windows and doors. Add the walls together for your total area in m².
2. Choose the insulation type and thickness
EPS is the most popular choice for houses. Mineral wool is used where fire performance or breathability is a priority. Check the thickness you need to reach your target U-value.
3. Calculate the materials
Enter your wall area, house type and finish into the EWI cost calculator. You get a full list of boards, adhesives, mesh, fixings, primer and render with a NET price.
4. Add labour and scaffolding
Ask installers for a labour price per m² and a separate scaffolding quote. Get at least three quotes from experienced EWI installers.
5. Add extras and a contingency
Include sills, flue extensions, wall repairs and 10% for unexpected work.
6. Check grants and VAT
Funding may cover part or all of the cost for eligible households, and professional installation of insulation currently benefits from 0% VAT in Great Britain. See below.
How to reduce the cost of external wall insulation
- Choose the right system for the building. EPS costs less than mineral wool and is suitable for most houses.
- Order an accurate quantity. Over-ordering boards and render is a common hidden cost – an accurate take-off from the calculator prevents it.
- Buy the complete system from one supplier. Compatible adhesive, mesh, primer and render reduce the risk of failures and make bulk pricing easier.
- Ask about trade prices on bulk orders. Installers and builders pricing several properties can get better rates.
- Share the scaffolding. Plan roof, gutter or window work while the scaffolding is up.
- Pick a standard render colour. Standard shades are cheaper and faster to supply. See our colour chart.
- Collect your materials. Save on delivery by collecting from our store at 17 White Lion Road, Amersham, HP7 9HZ.
Grants and VAT on external wall insulation
Grants
Government-backed schemes can cover part or all of the cost of external wall insulation for eligible households, depending on income, benefits, property type and EPC rating. Eligibility and funding levels change regularly – read our up-to-date guide to external wall insulation grants before you commit to a quote.
VAT
Professional installation of energy-saving materials, including wall insulation, is currently zero-rated for VAT in Great Britain. Materials bought on their own, without installation, are charged at the standard 20% rate.
Is external wall insulation worth the cost?
For solid-wall homes, EWI is usually the most effective way to cut heat loss through the walls. The Energy Saving Trust estimates savings of several hundred pounds a year on heating bills for a typical home, plus improved comfort, fewer cold spots and condensation, a refreshed exterior and a better EPC rating. Payback is long without funding, but the system typically lasts 30 years or more – and with a grant, the return is much faster.
External vs internal vs cavity wall insulation cost
| Type | Typical installed cost per m² | Loss of room space | Best for |
|---|---|---|---|
| External wall insulation | £100-£180 | None | Solid-wall homes, full retrofit, refreshing the exterior |
| Internal wall insulation | £70-£120 | Yes | Flats, listed or conservation-area buildings |
| Cavity wall insulation | £15-£30 | None | Homes with unfilled cavity walls |
Calculate your EWI materials and cost
Every house is different. Our free EWI cost calculator takes your wall area, house type, insulation thickness and finish, and gives you a full list of materials with quantities and a NET price – ready to add to your basket in one click.
Frequently asked questions
How much does external wall insulation cost per m² in the UK?
Fully installed external wall insulation typically costs £100-£180 per m² in 2026, with most projects around £120-£150 per m². Materials alone cost around £35-£55 per m² (ex. VAT) for an EPS system with render.
How much does external wall insulation cost for a 3-bed semi?
A typical 3-bed semi-detached house has 80-110 m² of external wall. Expect £10,000-£18,000 fully installed, including scaffolding.
How much does external wall insulation cost for a terraced house?
A mid-terrace usually only needs the front and rear walls insulated, around 40-60 m². Expect £6,000-£11,000 fully installed.
Is mineral wool more expensive than EPS?
Yes. Mineral wool systems typically cost £20-£40 more per m² installed than EPS, because the boards cost more, are heavier and take longer to fix.
Is scaffolding included in the price of EWI?
Not always. Many installers quote scaffolding separately, typically £1,000-£3,500 for a house. Always check what your quote includes.
Is there VAT on external wall insulation?
Professional installation of insulation is currently zero-rated for VAT in Great Britain. Materials bought without installation are charged at 20%.
Can I get a grant for external wall insulation?
Yes, if you meet the eligibility criteria. Funding can cover part or all of the cost. See our external wall insulation grants guide.
Buy external wall insulation materials from Penguin BM
Penguin BM supplies complete EWI systems – insulation boards, adhesives, mesh, fixings, primers and renders – to installers, builders and homeowners across the UK. Trade prices on bulk orders, fast UK delivery and collection from our Amersham store.
Penguin BM
17 White Lion Road, Amersham, HP7 9HZ
Phone: 07515 283453
Email: info@penguinbm.com
Mon-Fri: 6:30 AM – 5:00 PM
Sat: 6:30 AM – 1:00 PM
Sun: Closed
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