Can he fix it?

We all know someone who has been through the mill at the hands of a cowboy builder. Whether it's bodged work, shoddy materials, lost prepayments and deposits, or even threats and intimidation, it's enough to put you off home improvements altogether.

But following a few basic rules will reduce the risks and help smooth out the process. For a start it's a good idea to avoid a contract that requires you to pay a deposit or substantial advance payment. If a builder insists on this try to find out why.

Sometimes it may be reasonable to pay money in advance - to a small business, for example, to finance the purchase of materials. But make sure you pay only what is needed at that stage. And try to agree staged payments as these encourage the builder to work to agreed deadlines.

Never hand over cash. Pay by credit card if you can or, failing that, write a cheque so you have a record of the payment. And if you pay by credit card and the work costs ?100 or more, you can claim compensation from the credit card company if it all goes wrong and the builder disappears or goes bust.

Prices vary hugely; so don't settle for the first firm you find. Shop around and get a price from at least three firms to compare costs. When you ask for a price you'll be given an estimate or quotation but legally the two are very different.

An estimate is only a provisional guide, and may be increased after the work has started. A quotation is a firm and definite price, which can't be altered at a later date. Always insist on a quote in writing and if you accept it, sign it and write on it "I accept on the basis that it is a firm and definite price for the job."

Insist also on a written agreement, which states clearly what needs to be done. For smaller jobs a letter of agreement signed by you and the builder will probably do. But if the work is going to cost more than a few thousand pounds you must get a proper contract drawn up.

Your written agreement with the builder should detail the precise nature of the work, the quoted price, commencement and completion dates, method of payment - whether by stages or lump sum - responsibility for clearance of rubbish and so on. Make sure it spells out clearly who is responsible for buying the materials. And check the small print for exclusion or get-out clauses.

Building work must be carried out within a reasonable time. If you haven't agreed a completion date and there are delays, you can encourage a builder to finish a job by making time of the essence. Write to the builder stating that the work must be finished within a reasonable time period and provide a fixed date. Then if you are let down and they miss the deadline you are entitled to cancel the contract and claim compensation.

The Supply of Goods and Services Act 1982 says building work must be carried out with reasonable care and skill. The standard required is that of any other competent member of the trade in question. And the materials used must be of satisfactory quality and fit for their purpose.

So if the builder installs a faulty set of doors the responsibility lies with him and not the supplier, even if the defect in the doors is down to a manufacturing fault. However, if you insist on particular materials that later turn out to be unsuitable for the job, then you are responsible.

If the work is bodged you should usually give the builder a chance to put the matter right. Unless the builder's work or behaviour is so appalling you could be said to have lost all confidence in him. Be careful though, if you don't give the builder a second chance, your compensation could be reduced on the basis that you didn't mitigate your loss.

Failure to bring the work up to scratch means the builder is in breach of contract. You will need to get evidence that the work is not of a reasonable standard. Written opinions from other contractors will probably be enough for small jobs. But for expensive building work, you may need to get an independent report from a surveyor. Only when you have written proof of the defects is it safe to get another builder to complete the job properly.

Generally you can claim compensation from the builder for any expenses you incur above the quoted price. So if it costs you more to use a new builder to complete the job properly you can claim the difference. To work out how much you should pay the original builder deduct the cost of using another builder from the original quote. And if you've had a lot of hassle you can also deduct an amount for inconvenience together with expenses such as the cost of any surveyor's report that you may have used.

Of course, a lot of these problems would not arise if you could manage to find a decent builder in the first place. For tips on choosing a reputable builder and further guidance see our article Choosing and using a builder. Once you've got your dream builder, find out how to treat him here. And for more detailed advice check out the step-by-step guide to getting work done on your home published by the OFT.