Here's what you need to ask your builder before you sign on the dotted line, including some expert advice from Daniel Moore of DJ Moore Lofts, loft conversion specialists and certified VELUX installers based in Milton Keynes.

1. What experience do you have with my kind of project?

It’s important that your builder has right skill set, so ask how many projects of a similar type to yours they’ve done. If you’re after a loft conversion, go for a loft conversion specialist. If you’re doing an extension, make sure your builder is experienced in doing those. You’re investing your hard-earned cash so make sure your builder has the required know-how and is not using your project as their learning experience.

2. Are you accredited?

“It’s essential to do your due diligence and make sure you’re dealing with a reliable business,” says Moore. Ask your builder if they are a member of a trade body - look for the Federation of Master Builders (FMB). The FMB has a code of practice and stringent membership criteria, including solvency and safety, so membership is a good indication you’re picking a reliable and trustworthy professional.

3. Can I see some finished projects?

While credentials are important, the proof is the pudding! Ask the builder to show you examples of completed projects, ideally similar to the one you’re planning. A quality builder will have plenty of case studies to show you.

4. Can I see a project in progress?

If you like to be extra thorough, ask the builder if they have any local projects still in progress. Driving by for a look can give you a good indication of how the company operates - such as how tidy they are during the building process!

5. Do you have references and reviews?

Ask if they can give you contact details of previous clients. Speak directly to recent clients about their experience of working with the builder, from timescales to communication to the quality of the build.

Moore also recommends always checking third-party reviews. “A business can put anything on their own website, so check out reviews on independent websites like MyBuilder, Trustpilot and Facebook.”

The golden standard of reviews are those from Which. “If a builder is an accredited Which Trusted Trader you know they’ve gone through an extremely stringent vetting process,” says Moore. “Also, client reviews submitted to Which are individually and independently verified.”

6. Is your price a quote or estimate?

Be sure to distinguish between an estimate and a quote. An estimate is not binding, while a quotation is an undertaking to complete a job based on the provided specification and drawings, for the stated price. The quotation should include all of the work to be done, with all costs itemised from materials and labour, right down to rubbish removal costs like skip hire.

7. Do you have insurance cover?

In the rare event that things go wrong, it’s good to prepared. Ask your builder if they are properly insured. They are legally obliged to have both public and employers liability insurance - you can ask to see their certificates.

8. Do you offer a guarantee of your work?

“We offer a five year guarantee as standard,” says Daniel Moore. A reputable company should offer a guarantee.

9. What are your payment terms?

A reputable builder will never ask for payment up front. Most will agree a schedule of staged payments throughout the project, before work commences. The final balance should be due only upon satisfactory completion of the project.

10. How will we communicate?

“Trust and communication are big parts of the process”, says Daniel Moore. You may just want to leave your builder to get on with the job, but clear and regular communication is essential. Ask your builder how often they will update you on progress, how best to contact them with queries, and how soon you can expect a response.

11. When can you start?

“This is a biggie,” says Moore. “Some companies aren’t honest or realistic about lead times. They may say they can start quickly in order to win your work. Make sure your prospective builder is giving you a timescale that is actually possible. It’s so gut wrenching to be geared up for your project to begin only for a builder to say they need to delay it.”

The right builder may not be the one who can start the soonest, but rather the one who can give you a detailed plan for the project and estimate a realistic finish date.

12. What are you like to work with?

This may feel like an awkward question, but Daniel Moore says it’s important that you get along with your builder. “Our loft conversions range from three weeks to six weeks, so you need to be comfortable with having people in your home over a long period. You're going to see them near enough daily, so you want to work with someone approachable and friendly. You need clear lines of communication, so you don’t feel any hesitation asking questions throughout the build.”