How to choose a London builder (without getting burned)
The questions to ask, the paperwork to demand, and the red flags to walk away from when hiring a builder in London.
Half the horror stories you hear about London builders come down to the same few decisions made badly at the start. Here's the short list that separates a clean job from a nightmare.
Ask for Checkatrade, Trustpilot, or Google reviews — at volume
One glowing testimonial on a builder's own site means nothing. You want 20+ independent reviews across a verified platform (Checkatrade, Which? Trusted Trader, Trustpilot, Google Business). Read the middle ones, not just the 5-stars — they're usually more revealing.
Demand proof of insurance
Public liability (£2m minimum, £5m preferred for bigger jobs), employer's liability (mandatory by law if they have staff), and contract works insurance. Ask for the certificate. A real builder sends it over in an hour. A chancer stalls.
Written scope — or walk away
A proper quote is itemised. "Bathroom refit: £18,000" is not a quote; it's a hostage note. A real quote lists strip-out, waste disposal, first-fix plumbing, first-fix electrical, tanking, tile labour, fittings (named brand and model), second-fix, sealants, snagging. If they can't produce one, they haven't priced the job — they've guessed.
Payment structure
Red flag: more than 30% up front. Normal for a big job is a deposit (10–20%), then staged payments tied to milestones (first fix, second fix, completion), with a small retention (usually 5%) held back for 6–12 months against snagging. Never pay 100% before completion. Never pay cash.
Gas, electrics, building control
- Gas work — must be Gas Safe registered. Check the number at gassaferegister.co.uk.
- Notifiable electrical work — must be Part P certified (NICEIC, NAPIT, ELECSA).
- Structural changes, extensions, loft conversions — need Building Regulations approval, either through your council or an Approved Inspector.
- Listed buildings — need Listed Building Consent before any work starts.
Ask specifically who will sign off each bit. If the builder sub-contracts gas or electrics (common, and fine), ask for the sub-contractor's credentials too.
Red flags to walk away from
- Cash only or "mate's rates" without paperwork.
- Pressure to decide quickly ("we've got a gap next week").
- Reluctance to put anything in writing.
- No fixed address or a PO box.
- Brand-new website, no verifiable history.
- Quotes wildly below others ("how are they doing it for that price?" is the right question).
- Changing the spec mid-job and charging for extras that should've been in the original quote.
The boring test
Call their last three jobs. Ask the homeowner: did they turn up when they said? Did they clean up? Did they snag properly? Did the price hold? A good builder gives you those numbers happily. A bad one finds reasons not to.
We're on Checkatrade, we carry full insurance, and every quote we send is itemised. Book a consultation and see the difference.
