London & South-East England
External Wall Insulation (EWI)
External wall insulation wraps the outside of your home in an insulating board, then finishes it with a protective, weatherproof render. For the solid-wall Victorian, Edwardian and pre-1930s housing that dominates much of London and Kent, it is the single most effective thermal upgrade available — typically cutting wall heat loss by around 70% without losing a single centimetre of internal floor space.
Is EWI right for your home?
- Solid-wall properties (typically pre-1930s) with no cavity to fill
- Homes outside conservation areas where external changes are permitted
- Owners wanting the biggest possible thermal gain in one project
- Tired pebbledash or render façades due for refurbishment anyway
- 1930s–1960s semis where the whole house can be treated at once
What is external wall insulation?
Because the insulation sits on the outside, EWI also eliminates cold bridging, protects the original brickwork from weather, and gives tired façades a clean, modern finish. The trade-off is that it changes the external appearance, so it is not suitable for most conservation areas or listed frontages — in those cases internal wall insulation is the right call.
We are a PAS2030-19 and TrustMark certified installer and fit manufacturer-approved systems end to end with our own trained team — no subcontractors. Where your household is eligible, the work can be fully or partly funded under ECO4 or the Great British Insulation Scheme, and we handle the application from start to finish.
External Wall Insulation cost guide
Indicative 2026 pricing for London & the South-East. Every quote is free, fixed and itemised — grants can reduce or remove these figures for eligible households.
| Job type | Indicative cost |
|---|---|
| Mid-terrace (rear/side elevations) | £8,000 – £14,000 |
| Typical 3-bed semi-detached | £12,000 – £20,000 |
| Detached house | £18,000 – £30,000+ |
| Per m² (system + render + labour) | £90 – £140 / m² |
Recent EWI work
Real jobs completed by our own team across London and the South-East.
90mm EPS External Wall Insulation
External wall insulation in Harrow
Brick Slips
Brick slip installation instead of render
External Wall Insulation
Finished Install in SW London
Systems & materials we install
How EWI installation works
Free survey
We assess wall construction, check for damp, measure up and confirm whether EWI is the right specification for your property.
Specification & quote
A fixed written quote within 24 hours, including board type, render finish, scaffolding and making good — plus grant eligibility if applicable.
Installation
Scaffold up, boards mechanically fixed and bonded, beads and mesh set, then base coat and decorative render applied by our own team.
Sign-off & guarantee
Final inspection, TrustMark lodgement, and a manufacturer-backed system guarantee (typically 25 years).
Grants for external wall insulation
We're TrustMark-registered for ECO4 and the Great British Insulation Scheme. If your household qualifies, this work can be fully or partly funded — we handle the application end-to-end.
Check my eligibilityExternal Wall Insulation FAQs
How much does external wall insulation cost?
Do I need planning permission for EWI?
Will EWI cause damp?
How long does it take?
How much will it save on heating bills?
Areas we cover
We install external wall insulation across London and the South-East. See all areas we cover →
Other insulation services
Get a free EWI quote
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