How to check a builder before you let them start
The checks worth more than any review score: Companies House, insurance certificates, references, the written scope, and the payment patterns that should worry you.
Anyone can call themselves a builder. There is no licence to lose and no register to be struck off, which puts the whole burden of checking on the person paying.
The good news is that the checks that matter are quick, mostly free, and mostly public. Run them all on everyone you are considering — including us.
Companies House, first
Search the company name and number at Companies House. It is free and it takes two minutes. You are looking for whether the company exists, how long it has existed, who the directors are, whether accounts are filed and up to date, and whether there is anything on the register — a proposal to strike off, a charge, a change of name.
Check the number matches the one on the quotation and the website. A limited company must state its registered number and registered office; if it does not, that is itself worth asking about. Also look at the directors' other companies. A pattern of short-lived companies with the same director and the same trade is the single most useful thing the register will tell you.
Insurance — see the certificate, not the claim
Ask for the public liability certificate and the employers' liability certificate. Read the dates and the insured name, and check the insured name is the company you are contracting with rather than a similar one.
Employers' liability is compulsory for any company with employees and the certificate must be available. Public liability is not legally compulsory, which is exactly why the certificate matters.
On anything structural, ask specifically whether the policy covers the work you are having done. Some policies exclude underpinning, demolition and work to structure, and finding that out afterwards is the worst possible time.
References that are worth taking
Ask for two or three recent clients with jobs like yours, and ring them rather than reading a testimonial. The useful questions are not "were you happy".
Ask: did the price change, and why? Did it finish when they said? What went wrong, and what did they do about it? Were they still there for the snagging? Would you use them again for something bigger?
The answer to "what went wrong" is the one that tells you most. Every job has something. A contractor whose references cannot remember anything going wrong either had very small jobs or has coached them.
The written scope
A quotation should say what is included, what is not, what the payment stages are, and what would change the price. A single figure on a page with the job described in six words is not a quotation; it is an opening position.
This is the document you will be arguing from if things go wrong, and its quality is a fair proxy for how the job will be run. A contractor who writes a clear scope is a contractor who has thought about the work.
Payment patterns that should worry you
Payment should follow work done or materials delivered, in stages, agreed in writing before anything starts.
The warning signs
- A large payment demanded before work begins
- Cash only, or a discount for cash — it usually means no VAT record and no paper trail
- Payment into a personal account when you are contracting with a limited company
- Stage payments that run ahead of the work on site
- Pressure to decide today because the price goes up tomorrow
- No written quotation, or one that arrives only after you have committed
Trade memberships: useful, not proof
Membership schemes vary enormously. Some vet properly and inspect work; others take a subscription and issue a logo. Check the membership number on the scheme's own website rather than trusting the badge on a van.
Where a scheme is a statutory competent-person scheme — a Gas Safe registration for gas work, a Part P registered electrician for notifiable electrical work — that one is not optional and you should see the registration.
What to keep
Keep the written quotation and every variation, the insurance certificates, the building control application and the completion certificate, any structural engineer's calculations, and the guarantees and product warranties at the end.
That folder is what you hand a buyer's solicitor. It is worth more at the point of sale than most of what people spend money on.
Where this comes from
Everything on this page was checked against the primary source in September 2026. Regulations, designations and thresholds change, and nothing here is a substitute for advice on your own property or contract. If you spot something that has moved, tell us and we will correct it.
The sources are listed opposite. They are the published guidance and legislation themselves rather than a summary of them, so you can check any of it directly.
Common questions
Questions on this
What are ATR's details?
ATR Developments Limited, company number 16319104, incorporated 16 March 2025, registered office 383 Whitehall Road, Wyke, Bradford, BD12 9DP. Search the number at Companies House. Our insurance certificates are on the accreditations and insurance page and we will send them on request before you commit to anything.
Does a young company mean higher risk?
It means the trading history is short, and you should say so rather than pretend otherwise. Judge it on what can be checked: who the directors are, what the people have built before, whether the insurance is real, whether the written scope is any good, and what the references say. We would rather be assessed on that than on a number of years.
Should I use a contract for a domestic job?
For anything substantial, yes. A written contract setting out scope, price, programme, payment stages, variations and what happens if something goes wrong protects both sides. Note that the Construction Act's payment and adjudication provisions do not apply to a contract with a residential occupier, so what your contract says is what you have.
How do I check an electrician or gas engineer?
Both have statutory registers. Gas work must be done by a Gas Safe registered engineer — check the number on the Gas Safe register. Notifiable electrical work must be certified, either by an electrician registered under a Part P competent person scheme or through building control. Ask for the certificate at the end; it is part of the paperwork a buyer will want.
Where this applies
The work this affects
- Home extensions Single and two-storey rear, side and wraparound extensions, from first survey to building control sign-off.
- Full house renovations Whole-property refurbishment — strip out, first fix, second fix and finishes under one contract.
- Landlord & rental refurbishment Bringing a tired property back to a lettable standard, on a programme built around void periods.
Start a conversation about your project
Tell us what you are planning. We will come out, look at it properly, and put a written quotation in front of you.