Hello, are there any decent and honest builders out there?

If a poltergeist makes a mess of your home, you can call an exorcist, but finding good craftsmen to rectify mistakes seems impossible.

The plumbing leaks. Doors swing open. Floorboards squeak and the central heating bangs. And is that the alarming whiff of sizzling electrical insulation? For the psychically inclined the clues might point to a poltergeist. Sophisticated home owners will recognise them as the signs that shoddy builders have made "repairs".

Any old exorcist can remove evil spirits from a home, but finding a builder who can rectify others' mistakes is much harder. Shady operators - known as cowboys although the term does a disservice to professional cattlemen - abound. The Institute of Trading Standards Administration and the AA estimate that pounds 1bn out of the pounds 8.5bn spent each year on home maintenance still goes to the "informal economy". And pound for pound there are six times as many complaints about building work as there are about cars.

In 1995 the Office of Fair Trading recorded 49,000 complaints against builders, of which a mere 22 received the department's sanctions. Many of the rest were dealt with locally, but for each unhappy customer who went to the trouble of complaining to trading standards authorities, dozens more fumed in silence. This leaves two questions: why are good builders so rare and, more importantly, how do you find one?

Part of the problem with builders is that the best are lured by the relatively high pay of commercial construction. Wander through the City headquarters of a financial institution and you won't see much slip-shod workmanship. Many domestic builders, says Jeff Howell, senior lecturer in construction technology at the South Bank University, are not good enough to work on commercial projects. And unlike the professions, most trades have no formal requirements. If they can swing a hammer, they can call themselves builders. True, there are National Vocational Qualifications for most building trades, but they are not requirements for entry. Nor are they enough, argues, Alan Atkins, lecturer on building studies at Lewisham College. "We had this silly idea that we could train someone for a craft while they were out of work." What is needed is something like the old fashioned apprenticeship. Too often the choice is between someone with exams but no experience, or one who has picked up all the bad habits of whichever uncle taught him the business.

Another problem is that builders often do not stay in business for long. Of the first eight display ads, selected randomly from a 1992 copy of the London Yellow Pages, seven were no longer builders. Longevity is not necessarily a guide to scrupulousness, however. One successful builder specialised in the roofs of terraced houses for years. His secret was that while doing one job, he would remove a few tiles from neighbouring houses, then offer his services to the unwary victims of his vandalism.

Nor is membership of a guild or trade association a guarantee that a tradesman is reputable. According to the Consumers' Association, many of them are marketing gimmicks. Which? magazine reported last summer that one of its researchers asked to join the Guild of Builders and Contractors as an interior designer, though she had no experience. She was granted a certificate on payment of her pounds 35.25 membership fee.

At least three other methods are available, with a trade-off between cost and reliability. Gathering word- of-mouth recommendations costs nothing but time. However, the work on which the recommendation is based might have been quite different from the job you want done.

Second, there are helplines offered by AA, Green Flag and Barclaycard that will recommend local builders. Membership of these organisations usually costs an annual fee. The reputable ones check the work of the builders they recommend and have a complaints procedures. Third, there are architects, surveyors and building engineers. For a fee they will draw up specifications for the job, gather quotes, and supervise. It may cost more, but the professionals are more likely to spot sub standard work.

For those determined to go it alone, architect Mary Johnson of Jay Design Architects in Greenwich has some advice that will help to protect from the worst offenders:

Find four to six builders and ask them to tender for the job that needs doing. Personal recommendations from friends and neighbours are the best way to find these builders, but failing that phone books could be used, or a scouting trip through the neighbourhood in search of building sites that are kept neat and tidy - a sign of professional pride if nothing else. It's best to look for local builders so there's no extra cost for travelling. l Ask lots of questions. Make sure the builder is neither too big nor too small for the work that needs doing. And find out how busy they are. There reason one can start right away might be because no one else will hire him. One that is too busy might take ages to finish the job. Most importantly, ask to look at some of the work they have recently completed. Also ask to see their public liability insurance certificate - it should be for at least pounds 250,000 for a small job, and pounds 500,000 for bigger ones.

Collect the quotes. The details of the job that needs doing should be written down, and presented to each bidder, so that their quotes will be comparable. If they all offer to do the job for roughly the same price, take the lowest bidder, but if one is significantly lower than the others, drop it as the chances of corners being cut is too great. And don't be fooled into thinking the highest bidder is offering to do the best work. More likely, he doesn't really want the job, and will only take it on if the margin is outrageous. All quotes should be in writing, and for work worth more than pounds 2,500, a contract would be advisable.

For additional piece of mind, clients could also ask for bank references, or check to see if the builder has county court judgements against him. There are also insurance schemes, such as the one offered by the National Register of Warranted Builders, which will pay for another member to complete work up to a maximum of pounds 10,000. Agree to make payments only in stages, as work progresses, with the final sum being released only after the work has been independently checked.

And if, after all these precautions, you still end up with a poltergeist, make lots of noise. Complaining might get compensation from the builder, his trade association or his insurer.