As soon as you know there's a problem, contact the builder or decorator and explain the situation. If you phone the builder, it's a good idea to follow up the conversation with a letter.

The letter should confirm the problem, what you agreed the builder should do about it and by when (unless they say they will visit to deal with the problem in the next few days).

Under the Supply of Goods and Services Act 1982, consumers who enter into a contract for goods and services can expect these to be supplied with reasonable care and skill. Remember this applies to plumbers and other tradesmen as well as builders.

Remember that where a trader guarantees their work for a set period of time that guarantees do not affect your legal rights to have work done with reasonable care and skill using materials that are of satisfactory quality, as described and fit for purpose. 

A trader would not be able to claim that you cannot get a repair on any work that you discover is not up to standard after your guarantee period is over. 

If the builder doesn't turn up when they said they would, contact them again. Whether or not they have a good reason for not turning up, agree a final date by which the work must be completed.

The builder or decorator may be busy, but they have breached their contract with you so they should carry out the remedial work as a priority.

If the deadline passes or the builder has done nothing to fix the problem, set them a final deadline for doing the work.

Make it clear that if they fail to meet the deadline you'll get someone else to do it and you'll be claiming back the cost from them.

Enclose quotes or estimates that you've obtained from other builders so your contracted builder can see how much you'll be claiming if they won't put the problem right.

Warn the builder that you'll take them to court if necessary.

If the builder or decorator still doesn't respond, check if they're a member of a trade association as there may be a dispute resolution scheme that you could use.

Good trade associations will vet prospective members, throw out bad ones and offer help if things go wrong.

If not, you may decide that court action is necessary. 

The Ministry of Justice Practice Direction on Pre-action Conduct sets out the steps the parties must take before going to court. 

Think about the evidence you would need to prove your claim if you went to court, for example photographs of the poor workmanship.

You may need to get a report on the work done. Try to reach agreement with the builder as to who should provide the report. 

Wherever possible this should be someone you both agree has the expertise to assess the issues and what will be necessary to put them right.

When the new builder or decorator has completed the work, write to the original builder claiming the money you've had to spend, detailing exactly what work was done.

If they don't pay up, you'll have to start court proceedings to claim the money back. 

If the amount involved is less than the limit of £10,000 in England and Wales and £3,000 in Scotland and Northern Ireland, you'll be able to use the small claims court.

The small claims court is a quick and simple way of using the courts to settle disputes - you don’t need a solicitor, and the hearing itself is fairly informal. But it should only be used as a last resort.