How to check a builder's credentials before hiring in the UK

Before engaging any builder for work over £2,000, verify two things: public liability insurance and trade body membership. Public liability insurance (minimum £1 million, ideally £2–5 million) protects you if the builder damages your property or injures a third party during the work. Ask to see the insurance certificate and check the expiry date and coverage level.

The main trade bodies for builders and general contractors in England are the Federation of Master Builders (FMB), the National Federation of Builders (NFB), and TrustMark (a government-endorsed quality scheme for home improvement work). FMB membership requires passing a credit check, an independent inspection of recent work, and holding public liability insurance. Verify current FMB membership at fmb.org.uk.

TrustMark (trustmark.org.uk) is a government-backed scheme that registers firms across all home improvement trades. A TrustMark registered builder has been vetted for trading standards compliance, insurance, and technical competence. Not every good builder is TrustMark registered, but it is a reliable positive indicator.

Always ask for references from two or three recent projects of similar scale to yours. A credible builder will provide contact details for recent clients without hesitation. Ring or email the references and ask: Was the work completed on time? Was the final cost close to the quote? Would you use them again? Did any problems arise, and how were they handled?

If possible, arrange to visit a recently completed project. This is easier for commercial projects or new builds; harder for domestic renovation work. However, many satisfied customers are happy to show their completed project to a prospective client. The willingness of a builder to arrange reference visits is itself a positive signal.

Check Companies House at companieshouse.gov.uk (free) for any company you are considering. Review the filing history: consistent late filings, multiple county court judgements (accessible via Registry Trust at trustonline.org.uk for a small fee), or recently dissolved related companies are warning signs.

Always use a written contract for any building work over £1,000. At minimum, the contract must specify: exact scope of work, materials specification, start and end dates (or milestones), payment schedule, and what happens if either party wants to vary the scope.

A reasonable payment schedule for domestic building work: 10–30% deposit on start (materials), stage payments at defined milestones, and a final retention (typically 2.5–5% of the total) held for 30 days after completion. Builders who demand 50%+ upfront before starting work present higher risk — this is legitimate for bespoke materials orders but unusual for standard domestic work.

Do not pay in cash without a formal receipt. VAT-registered builders must issue a VAT invoice; builders who are not VAT-registered should still issue an invoice on company letterhead with their Companies House number if registered as a limited company, or their name and address if trading as a sole trader.