How to choose a builder in London: a checklist before you sign

1. Check insurance in writing

Ask for current certificates for public liability and, if they employ staff, employer's liability insurance (a legal requirement for most employers). For larger projects, ask about contract works cover and any insurance-backed guarantee.

2. See real, recent work

Ask for references from London clients with similar projects, and if possible visit a finished job. A builder who has worked in your borough will know its building control and parking quirks.

3. Get like-for-like, itemised quotes

Ask at least three builders to price the same drawings and specification. Look for clear stage breakdowns, named provisional sums and what is excluded. See our 2026 cost guide.

4. Use a written contract

A written contract should set out the scope, price, programme, payment stages, how variations are agreed and how defects are handled. Standard forms such as JCT homeowner contracts are widely used. Never pay large sums up front; pay against completed stages.

5. Understand your own legal duties

Under the Building Regulations dutyholder regime, clients, designers and contractors each have duties to ensure work complies. Under the Construction (Design and Management) Regulations 2015, domestic clients' duties normally pass to the contractor. A competent builder will explain this.

6. Confirm who handles building control and party walls

Agree who submits the building regulations application, who books inspections and how you will receive the completion certificate at the end. See building regulations sign-off.

Red flags

• Cash-only payment or a large deposit before any work.
• No written quote, contract or verifiable business address.
• Advice that you "won't need" building regulations for structural work.
• Pressure to sign quickly.

Sources: GOV.UK: employers' liability insurance; HSE: CDM 2015 domestic clients.

Frequently asked questions