External Wall Insulation Cost UK 2026

External wall insulation (EWI) for a typical UK 3-bed semi costs £8,000–£15,000 in 2026 — including 90–120 mm EPS or rockwool insulation plus K-Rend or silicone render finish.

Quick answer

Typical UK price range: £8,000–£22,000. Typical time: 7–14 days.

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Insulation calculator

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Insulation type Loft insulation (270mm) Cavity wall insulation External wall insulation Internal wall insulation Spray foam loft (open-cell)

Area to insulate (m²)

Region London South East South West Midlands North of England Scotland Wales Northern Ireland

Specification level Basic / standard Mid-range Premium / high-end

Extras

Pre-install survey £80–£200 Vapour control layer £150–£400 Ventilation upgrade £200–£600

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Estimate only. Prices reflect 2026 UK market data — get quotes from local tradespeople for accurate pricing.

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Budget Under £5,000 £5,000 – £15,000 £15,000 – £30,000 £30,000 – £60,000 £60,000+ Not sure

Timeline As soon as possible 1 – 3 months 3 – 6 months 6+ months Just researching

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Key points

• £90–£150/m² of wall installed
• £8,000–£15,000 for a 3-bed semi
• Saves £400–£800/year on heating
• ECO4 grants often cover the full cost

Cost breakdown

Item	Low	High
Insulation (EPS 90–120 mm)	£3,500	£6,500
Mesh + render system	£3,500	£7,000
Scaffolding + access	£800	£2,500
Window/door reveals	£500	£1,500

Cost by UK region

Region	Typical cost
London	£20,250
South East	£18,750
South West	£16,500
Midlands	£15,000
North England	£13,500
Scotland	£14,250
Wales	£13,500

How to save money

• Always check ECO4 eligibility first — often free for eligible homes
• Specify breathable render system to avoid damp
• Order new windowboards and reveals at the same time

How to find a trusted tradesperson

Get at least 3 quotes from vetted UK trade networks:

• Checkatrade
• MyBuilder
• Bark

FAQs

Will EWI cause damp problems?

Not if installed correctly with breathable render. Always use a TrustMark / PAS 2030-certified installer.

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Disclaimer: Prices are guide ranges based on 2026 UK market data. Get quotes from local tradespeople for accurate pricing.