The most important thing is do avoid handing over cash or paying large sums in advance. Be wary of paying cash for a cheaper job, i.e. to avoid VAT, you may be going down a slippery slope of not doing things properly which may eventually mean your job is also not done properly.

Agree when you intend to pay, ideally after you are satisfied with the completed job. If it is a big job agree a schedule of staged payments which is fair to both parties.

To avoid bad tradespeople and to ensure you can find them should they not answer a mobile;

• Get proper contact details and check them yourself
• Check if the company is verified on the Companies House website
• Get phone details, ideally a land line or 0800 number and check it
• Get a physical office address

Get quotes in writing by email or in person if possible. Getting quotes online or by text is ok (make sure you accept the offer by replying). For large projects make a written agreement, schedule of works and snagging plans as part of a working document. Also;

• Agree expected quality of workmanship and materials in advance
• When will work start and when will project be finished, what happens if project over runs ?
• How long is the guarantee on work and materials eg 12 months
• Discuss onsite behaviour in advance (no smoking, swearing or using mobile phones for non-work purposes)
• Agree that your Extension Builder will remove all debris and rubbish and what level of tidying up you want after job