Buying a property with an extension: what solicitors check

Buying a property with an extension can be attractive. It may offer additional living space, increase the property’s value and better suit your needs.

However, extensions can also raise important legal and regulatory issues. Below, we answer some of the most common questions about the checks a solicitor will carry out when acting for a buyer.

Why does an extension require additional legal checks?

An extension changes the original structure of a property and may therefore be subject to planning, building control, and other legal requirements. Your solicitor’s role is to ensure the extension was constructed lawfully and does not create risks for you or your mortgage lender.

Will the solicitor check if the extension has planning permission?

Yes. One of the key checks is establishing whether planning permission was required and, if so, whether it was obtained. Not all extensions need planning permission, as some benefit from permitted development rights. Your solicitor will review the available documentation and relevant local authority information to confirm the position.

Can the local authority still take enforcement action if the extension is old?

Possibly, but this will depend on when the extension was built and what documentation is available.

For planning purposes, the enforcement rules changed significantly in April 2024. In England, unauthorised extensions completed on or after 25 April 2024 are generally subject to a 10-year enforcement period. However, extensions completed before that date may still benefit from the previous four-year time limit under transitional arrangements. Once the relevant period has expired, the development may become immune from enforcement action, although specialist advice should always be obtained before relying on this.

Building regulations are different. Formal enforcement action is generally subject to much shorter time limits. However, even where enforcement is no longer possible, the absence of building regulations approval or a completion certificate can still raise concerns for buyers, mortgage lenders and future purchasers.

What if the extension didn’t need planning permission?

Where an extension was built under permitted development rights, your solicitor may ask whether a Lawful Development Certificate was obtained. Although not always mandatory, this certificate provides official confirmation from the local authority that the development was lawful when it was carried out.

Are building regulations important?

Absolutely. Building regulations approval helps ensure that the extension meets the required safety and construction standards. Your solicitor will look for evidence of approval and a completion certificate issued by the local authority or an approved inspector. Missing documentation can raise concerns about the quality of the work and may affect future saleability.

What happens if there is no planning permission or building regulations approval?

If important documentation is missing, your solicitor will raise additional enquiries with the seller. Depending on the circumstances, indemnity insurance may be considered. However, this is not always suitable, and some mortgage lenders may require further evidence before they are prepared to lend.

Will the solicitor check for structural issues?

Solicitors do not inspect the physical condition of a property. However, they will consider any survey reports provided and raise enquiries where legal concerns arise. Buyers should always consider obtaining an appropriate survey to assess the condition of the extension and the wider property.

What about rights of way or boundary issues?

Extensions can occasionally encroach onto neighbouring land or interfere with rights benefiting adjoining properties. Your solicitor will review the title documents and plans to ensure the extension has not breached boundaries or affected any legal rights.

Will restrictive covenants be checked?

Yes. Some properties are subject to restrictive covenants that limit alterations or extensions. Your solicitor will check whether any restrictions apply and, if they do, whether the extension was built in compliance with them.

Are there any concerns with utilities or drainage?

Potentially. If an extension has been built over or close to a public sewer, consent from the relevant water authority may have been required. Your solicitor will check whether a build-over agreement was necessary and, where applicable, obtained.

What if the extension is quite old?

The age of an extension can be an important factor when assessing risk. Although statutory time limits may prevent enforcement action in some cases, older extensions with missing documentation can still raise concerns for lenders and future buyers. Your solicitor will assess the available evidence and advise whether the position is likely to affect the transaction.

Do mortgage lenders have specific requirements?

Yes. Most mortgage lenders require confirmation that any extension complies with the relevant planning and building regulations requirements. Any uncertainty or unresolved issues could delay the transaction or, in some cases, affect the lender’s willingness to proceed.

Can problems with an extension delay the purchase?

Yes. Missing paperwork, unclear permissions, boundary concerns, or other legal defects may require further investigation and resolution. This can lead to additional enquiries, negotiations, or the need for insurance, all of which can impact the timetable for the transaction.

Conclusion

When purchasing a property with an extension, thorough legal due diligence is essential. Your solicitor will investigate whether the extension complies with the relevant legal and regulatory requirements and identify any risks that could affect your ownership, mortgage, or future sale of the property. Resolving any issues at an early stage can help ensure a smoother transaction and protect your investment.

If you are considering buying a property with an extension and would like advice on the conveyancing process, our Residential Property team will be happy to help.