You'll not only endure weeks of builder's bum and builder's tea - a builder can make your project a dream or a nightmare. Find out how to choose wisely

A bad builder in your home can be an extremely stressful experience, but for every rotten apple there are many hard-working and responsible companies. The trick is knowing how to select them. Below is a step-by-step guide to rooting out the cowboys and picking a sure-fire winner.

Establish their credibility
A good building company will be affiliated to a renowned trade organisation like the Federation of Master Builders. Don't just take their word for it, ask for membership details and check with the member organisation. These associations guarantee a certain standard and have done in-depth research with previous customers to ascertain the builder's credentials. They are also an independent body you can appeal to if there are problems during the build and they offer a comprehensive 'Find a Builder' service. The other barometer is VAT registration. Don't be tempted by a deal for cash. Cowboys who cut corners on tax will cut corners on your job.

References, references, references
The best references come from friends and family. If someone whose judgement you value has had a positive experience, trust them. Otherwise, ask your builder for several references from recent customers. Every previous customer will provide a slightly different insight. A good builder will also offer to show you a current project so you can examine the standard of workmanship.

The paperwork
Two things are crucial here. Check immediately that they are happy to sign a contract. If not, alarm bells should ring. Secondly, ask for a fully detailed quotation, itemising every aspect of the job. A good builder will be happy to spend the extra time at the start of the job detailing the specification. Getting an itemised price for each element also allows you to pick and choose the most important parts of the job if you are on a tight budget. A good builder will advise you where best to spend the money. A comprehensive quotation gives you a better chance of keeping to budget and will flag up potential black holes where your costs could go up.

Pay peanuts, get monkeys
It is obviously always very tempting to go for the cheapest quote but this can often be short-sighted. Many unscrupulous builders will typically quote at least 15-20 per cent below what the job is actually worth, knowing that they can bump the price up with extras throughout the project. They will offer to do the job for cash, saving you VAT but, as they then cannot reclaim the VAT on materials, their costs go up. You can be sure it is you who will pay for it in the end.

Test their eye for detail
A good builder should also act as a design consultant. Look out for good suggestions when they come round to quote. Are they pointing out things you hadn't thought of or spotting things before you mention them? Are they advising you on the best use of lighting and space? Are they being pro-active and looking to improve your home as much as possible or do the bare minimum and get out of there as fast as possible. Sympathetic, design-focused builders can add literally thousands onto the value of your home.

Contacts
Do they have recommended architects and structural engineers they regularly work with? If your plans have not already been drawn up, ask to meet their architect. He will offer you another insight into your builder. Are they knowledgeable about different suppliers for both high-end products and stylish budget items?

Timings
When embarking on a building project, it is imperative to plan ahead. A good builder will never be able to start immediately. They are in high demand and you will often have to wait for a couple of months. If your builder can start tomorrow you have to ask yourself why.

Positive attitude
Does he have a positive attitude? Many builders when confronted with a tricky part of the job or a last-minute change will instinctively react negatively: 'That's gonna be difficult, luv, it's gonna cost you. You should have told me earlier' etc. A good builder understands that clients sometimes change their minds and that it can be difficult to visualise directly from the plans.

Trust your instincts
Above all, trust your instincts. You are going to have a very personal relationship with your builder during the course of your project and it is imperative you have a good working relationship. Does he have your best interests at heart? Is he happy to take the time to listen to your concerns and talk through your design ideas? Is he a good communicator? Does he explain things clearly or bamboozle you with technical jargon? A building project will always be stressful at times but is also very exciting; choose someone who will share your enthusiasm and develop your project as if it was their own.

Felix Milns is a journalist, property developer and building contractor. His company, Zulufish Ltd, specialises in design-led refurbishment, extensions and conversions in west and south west London. For more information contact Felix@zulufish.co.uk.