How to Check a Builder Is Legitimate Before You Hire Them

Check the company exists

If the builder trades as a limited company — anything ending in 'Ltd' or 'Limited' — search the name on Companies House. You want to see the status as 'Active', a registered address that makes sense, and accounts and confirmation statements filed on time; overdue filings are a warning sign worth asking about. The incorporation date also tells you how long the company has existed, which may be shorter than 'years in the trade', since many builders work as sole traders before incorporating. Sole traders and partnerships don't appear on Companies House at all, so absence alone isn't a red flag — it just means you lean harder on the other checks.

Check trade body claims on the trade body's own website

A logo on a van, a quote or a website proves nothing. Citizens Advice's guidance is to check a trader is a member of any scheme or association they claim by looking them up on that organisation's own register. The Federation of Master Builders has a public member search, as does TrustMark, the government-endorsed quality scheme. If a claimed membership doesn't show up, ask about it directly — it may have lapsed, or the badge may have come with a website template — but don't take it on trust. Under the Consumer Rights Act 2015, what a trader tells you about themselves can become part of your contract if you rely on it, so a false claim matters.

Check their insurance covers your job

Ask to see the insurance certificates rather than accepting a verbal yes, and check the dates run past the end of your project. Public liability insurance covers injury to people and damage to property, including your home and your neighbours'. If the builder has staff, employers' liability insurance is a legal requirement. For design work, professional indemnity insurance matters, and contractors' all-risk cover protects work that's damaged or destroyed before it's finished. Also ring your own home insurer: some policies change during major building work.

Talk to past customers, not just read reviews

Ask for two or three recent jobs similar to yours, with contact details, and actually call them — Citizens Advice notes that written references aren't always genuine. Ask whether the job finished on time and on budget, how problems were handled, and whether they'd hire the builder again. Online reviews are useful for spotting patterns, but Google itself labels its reviews as unverified, so look for detailed reviews spread over months rather than a burst of short ones in the same week. If you can see a finished job in person, do.

Gas and electrical work need the right registration

Anyone working on gas appliances or pipework must be on the Gas Safe Register — it's a legal requirement, not a nice-to-have, and you can check an engineer's card number online. For electrical work, use an electrician registered with a competent person scheme, which also means they can self-certify the work instead of you needing a separate building control application. A general builder will often subcontract these trades; ask who's doing them and check those people too.

Red flags that should end the conversation

Walk away from anyone who only gives a mobile number and no address, won't put a quote in writing, only accepts cash, wants most of the money upfront, pressures you to decide on the spot, or turned up uninvited saying they 'noticed something' on your roof. A price far below everyone else's is also a warning: Citizens Advice points out it can mean the trader lacks the skills, isn't being honest, or simply isn't quoting for the same work.

Frequently Asked Questions