Vetting a general building contractor in London before you sign: Companies House, insurance, staged payments and contracts

Commissioning a general building contractor in London - whether for a refurbishment, a rear extension or a whole-house reconfiguration - means trusting someone with your largest asset and a five- or six-figure sum. Unlike Gas Safe for gas work or NICEIC / NAPIT registration for much notifiable electrical work, there is still no universal licence for general builders. That gap is exactly where dishonest operators thrive.

This guide is a pre-signature checklist: how to verify the business, what a safe payment and contract structure looks like, which legal rights you already have, and what to do if the relationship turns. It is written for London homeowners and checked against official and consumer sources on 19 October 2026.

Start with the uncomfortable fact: no general builder licence

HomeOwners Alliance, reporting research with the Federation of Master Builders in 2025, found that 47 per cent of UK adults believe builders are legally licensed when no such general requirement exists. The same organisations have called for mandatory licensing. Until that arrives, every protection you have is one you activate yourself: identity checks, insurance, scheme membership you can verify, and a contract that controls money and scope.

Companies House and identity checks

If the contractor says they are a limited company, open Companies House and confirm:

• the company name and number match the quote, letterhead and bank account name exactly;
• the incorporation date - a company formed last month can be legitimate, but it is not evidence of a long track record;
• the directors' other appointments - a pattern of dissolved companies with unpaid creditors is a warning;
• accounts and confirmation statements are not overdue;
• the registered office is not only a mail-forwarding suite presented as a yard you can visit.

Sole traders will not appear as a company; ask for proof of identity, a matching public-liability insurance schedule, and a permanent address. Be wary of anyone who will only deal in cash, WhatsApp first names, or a different trading style on every document.

Insurance, Tax and scheme logos that mean something

• Public liability - ask for a current schedule showing indemnity limits and the business name. Call the broker or insurer's verify line if the sum is large.
• Employer's liability - required if they employ staff; its absence on a gang of workers is a red flag.
• Contract works / all-risks - clarify whether your buildings insurance or theirs covers the works; tell your own insurer before work starts.
• TrustMark - confirm on trustmark.org.uk against the trading name and address on your paperwork, not a logo on a van.
• Federation of Master Builders or similar - again, check the member directory, not a certificate photo.
• Specialist registers when relevant - Gas Safe for gas, NICEIC or NAPIT for notifiable electrical work. A general builder who "has a guy" still needs those certificates in the right names.

Quotes, estimates and a written scope

Citizens Advice draws a useful distinction: a quote is generally a fixed price the trader should stick to unless you agree extras; an estimate is a guided figure that can change, though the final bill must still be reasonable. For building work, insist on:

1. drawings or a written specification the price is based on;
2. a priced breakdown (preliminaries, structure, first fix, second fix, finishes);
3. exclusions listed plainly - decoration, kitchen supply, landscaping, party wall fees, council fees;
4. provisional sums called out, with a rule for how they are adjusted;
5. programme dates and what happens in bad weather;
6. who applies for building control and who collects the completion certificate;
7. whether VAT is included.

Obtain at least three like-for-like tenders. HomeOwners Alliance recommends inviting enough firms that you can still compare three serious prices.

Staged payments that survive a disappearance

Citizens Advice advises: do not pay everything up front; where materials need a deposit, consider buying them yourself; keep any trader deposit as low as possible and do not agree more than 25 per cent; get a receipt; and check deposit insurance or an FCA-registered escrow if a larger sum is unavoidable.

A structure that works for many London domestic builds is:

• small mobilisation deposit against scaffolding or materials;
• payment after foundations / groundworks inspected;
• payment at watertight shell;
• payment at first-fix complete;
• payment at second-fix / plastering complete;
• retention of a final tranche until snagging is cleared and certificates are in your hand.

Never pay for work not yet done to "help cashflow" on another job. Prefer bank transfer to a matching company account over cash, and consider credit-card payment for a tranche that qualifies for Section 75 protection (more than £100 and no more than £30,000 for a single item).

Your legal footing when you sign

The Consumer Rights Act 2015 requires reasonable care and skill (s.49), can make the trader's pre-contract statements part of the contract (s.50), and requires performance within a reasonable time where none is fixed (s.52). Unfair terms - including inflated "non-refundable" deposits that do not reflect genuine loss - can be challenged; GOV.UK's cancelling goods or services guidance notes that cancellation charges must be a genuine estimate of direct loss.

If you sign at home rather than at the trader's premises, the Consumer Contracts Regulations 2013 generally provide a 14-day cancellation right for services. If you want work to start inside that window, expect a written request to begin early, and understand how that affects cancellation.

Specialist trades inside a general contract

A general builder often coordinates gas, electrical and waterproofing specialists. That is normal; what is not normal is leaving those names blank until something fails. Before you sign, ask who will carry out any gas work (must be on the Gas Safe Register), who will do notifiable electrical work (and which competent-person scheme they belong to), and who will issue the building-control completion certificate. Certificates should land in your name, not vanish into a subcontractor's van. If the main contract is silent on those points, add them as conditions of payment for the relevant stage.

Red flags that should stop the signature

• A price far below the other two tenders with no thinner specification to explain it
• Urgency ("we have a slot this week only") paired with a large up-front payment
• Refusal to put the scope in writing or to name subcontractors for gas and electrics
• Company details that do not match Companies House, or insurance schedules in another name
• Requests to pay a personal account, overseas account, or cryptocurrency
• Disparagement of written contracts as something "only solicitors need"

When work goes wrong

Gather the contract, photos, messages and dates. Write to the contractor stating that you expect the work to meet the Consumer Rights Act standard of reasonable care and skill, and set a clear deadline to return and remedy. Citizens Advice explains that if they cannot or will not fix it, you can seek a partial or full refund depending on severity, payable within 14 days of agreement; thereafter consider alternative dispute resolution, any trade-body process, and the Citizens Advice consumer service route into Trading Standards for unsafe or rogue trading. For unfinished sites, secure the property, notify your insurer, and take advice before commissioning another firm to complete someone else's work - clarify responsibility for latent defects in writing.

The best dispute is the one you never have: a verified company, a priced specification, insurance you have checked, and money that only moves when the build does.

Sources checked on 19 October 2026: HomeOwners Alliance on licensing misconceptions and extension costs; Citizens Advice, Before you get work done on your home; Citizens Advice, Problem with home improvements; GOV.UK, Cancelling goods or services; Consumer Rights Act 2015; Companies House; TrustMark; Gas Safe Register; NICEIC. Nothing here is legal advice.