One major factor when choosing a builder is this; 'don't assume your builder is a mind reader'.

With this in mind get your full specification down in writing. Don't forget such tasks as clearing up and tidying site at the end of the working day. If you expect your builder to clean up, put it in writing. If you expect your builder to dispose of building rubble ... record it.

Even if your builder tells you that you won't need planning permission, always check and confirm this with your planning office.

Don't be embarrassed to ask for references, and check them – anyone can say, “ I did the extension at no 44”. Pop around and have a chat with the occupier and ask if they are happy with the building work, the builders and crew and the after sales service; warranty and guarantee.

Ideally, you should obtain at least three builders quotes, but the more, the better. The cheapest isn't always the best option and double check that the quote complies with the written specification. Don't get drawn into 'estimates' – you need to demand a fixed quote. An estimate is only a flexible price that could soar when the work begins and estimates are always subject to change. Make sure you agree to terms in the event of further materials being required ..who pays?

Obtain at least three written quotes from different builders – do not always choose the cheapest. Make sure that all quotes reflect the same work specification in terms of materials, site clearance, time scale etc. Make certain that wherever possible these are fixed quotes rather than estimates which are subject to change.

Apart from references, ask your builder what types of work they have done before. They may specialise in certain jobs such as basement conversions, loft/attic extensions etc.

How long have they been in business? A long clean pedigree is worth far more than a nice man with a good sales pitch!

Do they have professional premises that you can visit and discuss the project further?

What guarantees to they offer? Is the guarantee backed by a reputable insurance company that will cover the work should the builder go out of business.

Does the builder have membership to a trade association or professional body? If they are, ring the association and verify their membership. Ask what protection they offer should the job go wrong. Is the builder signed up to a 'Considerate Constructors' scheme? Do they have an arbitration system should disputes fail.

These are sensible precautions and offer some sort of safeguard.

Building projects often go over time and over budget. Agree on an expected time frame and penalties should the deadline not be met ...get it in writing and signed.