Plan your London house extension with confidence.
Get an instant, realistic cost range and a shortlist of vetted London extension builders — in under five minutes.
Trusted by London homeowners across all 32 boroughs.
How it works
From “I want an extension” to a shortlist — in minutes.
Tell us about your home
A short 7-step wizard covers your property, extension goals and finish.
See a realistic estimate
Based on London-specific per-sqm benchmarks and projects similar to yours.
Meet vetted builders
Get matched with up to 3 KYB-verified specialists — no auctions, no spam.
London cost guide
Real ranges, not guesswork.
London extensions typically run £3,000–£5,000 per sqm for architect-led, mid-spec projects. Our estimator layers your type, size, finish and features on top of borough-level benchmarks.
Get my personalised estimate| Extension type | Typical size | London range |
|---|---|---|
| Side return | 15–20 m² | £65k – £95k |
| Rear extension | 20–30 m² | £85k – £130k |
| Wraparound | 30–45 m² | £120k – £185k |
| Double-storey rear | 40–60 m² | £165k – £260k+ |
Shell + fit-out; excludes land, party wall and unusual site constraints.
Recent projects
London extensions we've scoped.
What homeowners say
Built on trust, not lead auctions.
“The estimate matched what our builder actually quoted. Saved us weeks of guesswork.”
“Being matched with three properly vetted builders — instead of ten random ones — was the difference.”
“Loved how simple the form was. Felt like it was built for London specifically.”
Ready to see your numbers?
Answer 7 short questions to get your London-specific estimate and a shortlist of vetted builders.