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What to do if your house extension goes wrong?

More and more people are choosing to expand their current homes with an extension rather than to make the costly upheaval of moving. But before you venture into such a project you need to be aware of the potential pitfalls and how to protect yourself if in the unlikely event something goes wrong.

The Professionals

If you engage a builder or an architect to build or design an extension for you, you can expect it to be done with reasonable care and skill. Any materials used by the builder should be of satisfactory quality and fit for purpose. So, if something goes wrong with your extension then you must try first to communicate with the builder or architect. Explain the problem, how it can be resolved and give them a realistic timescale to do it.

If you talk to them directly or on the phone, record it in writing (email) immediately to them. Agree a date for them to complete the work. If they don’t rectify the problem, contact them again to agree a final date by which all the work must be done. Make clear that if they don’t, you’ll ask someone else to do it and you’ll be claiming back the costs from them.

If you can, when you’re requesting that a builder or architect to make good their work, include estimates from other builders/architects for the job. This lets them know how much you will claim from them if they don’t put the problem right. If they become awkward then notify them that you’ll take them to court if necessary.

Be careful asking another professional to complete the work. If you want to try and claim any money back, you need to have given the original professional an opportunity and time to fix the issue themselves first.

Withholding payment might help with negotiations but it’s not recommended. It could make the dispute worse and place you in breach of contract. This could allow the builder or architect to take legal action against you and a judge may take a dim view of you retaining money.

If resolving things amicably hasn’t worked, ask for their complaints procedure. If they don’t have one, find out if they’re a member of a trade association, as there may be a dispute resolution scheme that you can use. To use any resolution scheme, you’ll need to show that you’ve tried to resolve the issue with the professional first. If they have a complaints procedure, you’ll need to prove that you’ve used it and it hasn’t achieved resolution.

Builders don’t have to be part of an alternative dispute resolution (ADR) scheme or even obliged to use one for your dispute. But they are legally obliged to point you in the direction of an accredited scheme and specify whether or not they’re willing to use one. Different types of ADR includes: conciliation and mediation services; Adjudication and arbitration; and Ombudsman services.

If the professional isn’t willing to use an ADR scheme, there are other ways in which you can try to recover any money you’ve lost. If you used a credit card, it’s worth looking at whether you could recover the money using section 75 Consumer Credit Act. If the job cost more than £100 and less than £30,000, your credit card provider is jointly liable if something goes wrong. If you paid on a debit or prepaid card, or the cost was outside the limits for Section 75, making a  chargeback claim is another option. It isn’t a legal obligation, so banks have to agree liability. If you made a payment using PayPal or a finance agreement, you might be able to complain and get your money back through the Financial Ombudsman Service.

If you’re concerned that the builder or architect might not be acting lawfully, you could report the issue to your local Trading Standards.

The last resort should be to seek a resolution through legal action. Good evidence is key to proving your claim if you go to court including: photographs of poor workmanship; and an independent report about the work from an appropriate expert like a surveyor or architect setting out what can be done to make good the work.

If a new builder or architect has completed the work, write to the original professional claiming back the money you’ve had to spend and detailing exactly what work was done.This is called a pre-action Letter of Claim. 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 you’ll be able to issue your claim through the small claims court. The small claims court is a quick and simple way of using the courts to settle disputes and the hearing itself is informal. If you do decide to go to small claims court, you’ll be asked if you want to use the Small Claims Mediation Service first. This is free and will be provided by the court. If it doesn’t work, the case will be put forward for a hearing in court.

The Local Authority

If your extension requires planning permission or building control then the local authority’s own officers will inspect and sign off the works once completed. If they fail to spot something which was not completed properly or was done incorrectly, then they may also be liable to you. These are usually more difficult claims but you may be left with no option if the professional engaged to conduct the works is actually not a reputable company or individual and in fact has no means to satisfy any money judgment you obtain in court.


Once an extension is completed you should notify your home insurers as this may affect the premium.

In addition if something goes wrong with the extension, depending on the terms of the policy, there may be cover for remedy of some of the defects or the consequences of defective works.

In addition, if you also have Legal Expense Insurance cover as an additional element of your home, content or motor insurance, then they may provide cover for legal costs so that you can seek the appropriate remedy against the appropriate person.