Verified Extension Builders in London
Hire an identity-checked, insured extension builder in London — with milestone-escrow payments that release only when you approve the work. Post your job free and compare quotes from trades within 50 miles.
Verified London extension builders
Only identity- and insurance-checked extension builders can quote your job — no anonymous profiles, no cowboys.
Money held in escrow
Fund a milestone, approve the work, release the payment. Your money is protected at every stage.
Ranked on real outcomes
Trades carry an AxionOS Reputation Score built from completed, verified jobs — not fake reviews.
Hiring a extension builder in London
Extension specialists build out or up — single- or double-storey, side-return and wrap-around. Most of the cost is groundworks, structure and the roof; kitchens or bathrooms inside are extra.
Whether it’s a small repair or a major project, AxionOS matches you with verified London extension builders and protects the whole transaction. Describe the work — our AI Job Assistant turns a few words into a clear, quote-ready brief — then compare milestone-structured quotes and hire with confidence.
What a London extension builder covers
- Single & double-storey extensions
- Side-return and wrap-around builds
- Foundations, walls and roofing
- Building-control sign-off
Extension builder cost in London
Guide- Labour
- £9.4k–£35.4k
- Materials
- £10.6k–£39.8k
- Overhead & profit
- £3.5k–£13.3k
- Contingency (10%)
- £2.4k–£8.9k
+ £5.2k–£19.5k VAT if the trade is VAT-registered. Conservative national guide, adjusted for London — verified London extension builders quote a firm price for free.
Common questions
How much does a extension builder cost in London?
A extension builder in London typically works out around £26k–£97.4k (ex VAT, incl. a 10% contingency), driven by floor area (m²), number of storeys, glazing, and internal fit-out. That splits roughly into £9.4k–£35.4k labour and £10.6k–£39.8k materials. London sits above the national average, so figures are adjusted for the area. It's a conservative guide — post your job free to get firm, itemised quotes.
Are the extension builders on AxionOS verified?
Yes. Every trade clears identity and insurance checks before they can quote, and carries a public reputation score built from completed, verified jobs.
How does payment work?
Funds sit in milestone escrow. The extension builder completes a stage, you approve it, and only then is payment released — no payout without your sign-off.