How to choose a builder

Planning permission and building regulations

Many extensions are allowed under permitted development, but some need planning permission. Check with your council before work starts. Most building work also needs Building Regulations approval, from your council’s building control or a private building control body.

In England and Wales, work on a shared wall, or digging close to a neighbour’s foundations, can need a notice under the Party Wall etc. Act 1996.

Signs of a sound builder

Membership of the Federation of Master Builders (FMB) or TrustMark, the government-endorsed quality scheme, means the firm has been checked. Ask for addresses of past jobs you can look at.

For bigger projects, use a written contract that sets out the price, the stages, the payment for each stage and how changes are agreed. The FMB and JCT publish standard contracts for home building work.

Get quotes in writing

Ask two or three firms to quote for the same job, in writing. A quote is a fixed price. An estimate is only a best guess, and the final bill can be higher.

The quote should say what is included: materials, waste removal, making good, and any access equipment.

Check insurance and pay in stages

Ask to see their public liability insurance. Agree staged payments tied to finished work. A deposit for materials is normal on bigger jobs, but avoid paying the full price before the work starts.

Your rights

Under the Consumer Rights Act 2015, a trader must do the work with reasonable care and skill, in a reasonable time, and for a reasonable price if no price was agreed.

If you agree the job in your own home, you usually have 14 days to cancel under the Consumer Contracts Regulations 2013. If you ask for work to start sooner, you may have to pay for work already done.

For free advice on a problem with a trader, contact the Citizens Advice consumer helpline. In Northern Ireland, contact Consumerline.

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