Finding a reputable builder for an extension or renovation

An extension or a major renovation is usually the largest amount of money you will spend on your home after buying it. Choosing the builder carefully is the single biggest thing you can do to protect that money.

Get the design and paperwork right first

Builders quote against what they are shown. The clearer the drawings and specification, the more comparable the quotes.

• For an extension you will normally need drawings, and often an architect or architectural technologist to produce them.
• Check whether planning permission is needed or whether the work falls under permitted development. Your local planning authority can confirm.
• Building regulations approval is separate from planning permission and applies to most structural work, drainage, electrics and insulation. You can use the council's building control service or an approved inspector.
• If the work affects a shared wall or is close to a neighbour's foundations, the Party Wall etc. Act 1996 may apply and you may need to serve notice.

Having these in hand before you approach builders means you get quotes for the same job.

Where to look and what to verify

• The Federation of Master Builders (FMB) vets its members and you can check membership on its website.
• TrustMark is a government-endorsed quality scheme for trades working in and around the home. Registered businesses have been checked against its standards.
• For the individual trades within the job, the electrician should be registered with a competent person scheme such as NICEIC or NAPIT so the electrical work can be self-certified under Part P, and any gas work must be done by a Gas Safe registered engineer.
• If the builder is a limited company, check its filing history at Companies House. A long trading history and accounts filed on time are reassuring; a string of dissolved companies at the same address is not.
• Ask for public liability insurance and, if they employ staff, employer's liability insurance, and ask to see the certificates.

Ask for references for recent jobs of a similar size and, if you can, go and see one. Ask the previous client whether the job finished on time, whether the price changed, and whether snagging was dealt with.

Getting comparable quotes

Get at least three written quotes based on the same drawings and specification. Ask each builder to:

• Break the price down by stage or trade.
• State what is included and excluded, for example kitchen units, sanitaryware, decoration, skip hire and scaffolding.
• Say whether VAT is included.
• Give a start date, an estimated duration and any assumptions.
• Confirm whether they will use their own trades or subcontractors.

A quote that is significantly lower than the others usually leaves something out. Ask what.

The contract

Do not start a job of this size on a handshake. Use a written contract that sets out:

• The scope of work, referring to the drawings and specification.
• The price, and how variations will be priced and agreed in writing before they happen.
• A payment schedule linked to completed stages, not to dates. A modest deposit is normal; a request for a large sum up front is not.
• A retention, held back until snagging is complete.
• Start and completion dates and what happens if they slip.
• Who is responsible for building control inspections and sign-off.
• Insurance, site safety and waste disposal.

The Federation of Master Builders and the JCT both publish standard contracts for home owners that you can use. If you agreed the contract at your home, you normally have a 14-day cooling-off period under consumer contract rules. Under the Consumer Rights Act 2015 the work must be done with reasonable care and skill, and you are entitled to have defective work put right.

During the build

• Agree a single point of contact and a regular catch-up; weekly is typical.
• Keep a written log of decisions and variations, and confirm anything verbal by message.
• Never pay ahead of the agreed stages.
• Make sure building control inspections happen at the right points; you will need the completion certificate when you sell.

Warning signs

• No fixed address, no landline, cash only.
• Pressure to sign quickly or to pay a large deposit.
• Refusal to provide a written contract or references.
• A company that has only just been formed, especially if the director has previous dissolved companies.

Next steps

Get your drawings and permissions in order, then shortlist builders whose credentials you have checked. You can find builders near you on Annuvell Local; each listing shows checked contact details and a Request Quote option so you can send the same specification to several firms. Compare the quotes line by line, agree a proper contract, and pay only for work that has been done.