How to find a good builder, step by step

Step 1: build a long list of six to eight

Start wide. The best sources, roughly in order of usefulness:

• People near you who have had similar work done. Ask neighbours with recent extensions. A builder who did three kitchen extensions on your street knows the soil, the house type and the building control officer.
• Your architect or designer, if you have one. They see builders' work up close and know who answers queries well.
• Building control. Local authority building control officers will not recommend a builder, but you can ask a builder which recent jobs had inspections and when.
• Trade bodies and schemes such as the Federation of Master Builders or the government-endorsed TrustMark. Membership means vetting to a standard, not a guarantee of quality.
• Builders' merchants. The trade counter knows who pays on time and who is busy.

Treat online review sites with care. Use them for warning signs, not as proof of quality.

Step 2: check each one on paper

Before anyone visits, spend twenty minutes on each name:

1. Companies House. If they trade as a limited company, search the Companies House register. Check the company is active, accounts are filed on time, and the directors have no string of dissolved companies.
2. Trading address. A real address, not only a mobile number.
3. Insurance. Ask for public liability insurance details. £2 million to £5 million cover is common for domestic builders.
4. VAT number. If they will charge VAT, check the number using HMRC's VAT number checker.
5. Memberships. If they claim one, check it on the scheme's own website.

Cut the list to the four or five who pass.

Step 3: meet them at your house

A first visit tells you a lot. Notice whether they turn up when they said they would, whether they look at the drainage and the existing walls, and whether they ask about access, parking and neighbours. A builder who asks good questions is pricing properly.

Take the printable questions to ask a builder sheet. The most revealing questions are usually:

• Who will be on site day to day, and who is my contact?
• Which trades do you employ directly and which do you subcontract?
• What other jobs will you be running at the same time?
• Which contract do you normally use? (A builder who will not use a written contract is a red flag.)
• How do you handle changes and extra work?
• Can I see two jobs you finished in the last year, and one in progress?

Step 4: take up references properly

A reference is useful only if you ask specific questions. Phone or visit, do not rely on a written testimonial the builder provides. Ask:

• Did they finish on time? If not, why?
• How did the final cost compare with the quote, and why did it change?
• How did they deal with problems and with your neighbours?
• Did they come back to fix defects?
• Would you use them again for a similar job?

Seeing finished work in person beats any photo. Look at junctions: where new brick meets old, the plaster around window reveals, the line of skirting.

Step 5: get comparable prices

Send the remaining three builders the same drawings and specification and ask for a section-by-section price by a set date. Then compare them using the method in the quotes chapter and the quote comparison worksheet. If you are going design and build, ask each firm to price a common brief and list their assumptions.

Reading the answers: what good looks like

Most builders will say yes to most questions. The value is in how they answer. A few patterns worth noticing:

• Specific beats general. "Dave runs the site, he's been with us nine years, and our electrician is NICEIC registered" is a better answer than "we've got a great team".
• They ask about the drawings. A builder who wants to see the structural engineer's calculations, the drainage layout and the specification is planning to price properly. One who prices from a quick look round the garden is guessing.
• They talk about risk. Good builders mention the things that could go wrong on your job, such as a tree near the foundations, an old drain or a neighbour's extension, before you do.
• They are honest about time. "Sixteen weeks if the steel arrives on time, eighteen if not" is more trustworthy than a confident twelve.
• They put things in writing. Ask for the answer to one question by email after the visit. How quickly and clearly it arrives is a preview of the next six months.

Choosing a design and build company

If you are going design and build, add a few questions about the design side:

• Who does the drawings: an in-house designer, an architect, or a technician they subcontract to? Can you meet that person?
• Does their professional indemnity insurance cover the design work, and for how much?
• Will they give you a written brief and specification before the contract, so you know exactly what the fixed price includes?
• Can you keep the drawings if you do not proceed with them, and what does that cost?

The last point matters. Some design and build firms charge a modest design fee that is credited against the build. If you then go elsewhere, you want the right to use the drawings, which you can only have if the agreement says so.

Warning signs

Before you sign

1. Agree a written contract. See the JCT Minor Works chapter for forms that suit homes.
2. Agree a stage payment schedule with retention. Try the payment schedule worksheet.
3. Confirm who applies for building control and who serves party wall notices. See building control and party walls.
4. Tell your home insurer about the works.
5. Agree working hours, parking, toilet use and how site rubbish is handled.

Under consumer law, a builder must carry out a service with reasonable care and skill. If you sign the contract at home rather than at the builder's premises, you normally have a 14 day cancellation period, and the builder should give you written cancellation information. See consumer protection rights on GOV.UK.

Common questions