Extensions and Conversions: Planning and Building Regulations Checks Before You Buy in England

The Short Answer

Before you buy a property in England or Wales with an extension, loft conversion, conservatory or removed wall, check that the work had the right planning permission and building regulations sign-off. Missing paperwork can cause delays, affect mortgage lending and create costs for the new owner. Your solicitor should raise these points, but you should know what to ask for.

This Banke UK guide is general. Rules vary by local council, property type and the date of the work, so confirm the position with your solicitor and the local authority.

Planning Permission vs Building Regulations

These are two separate systems. Planning permission is about whether the work is acceptable in terms of use, appearance and impact, and some small works fall under permitted development. Building regulations are about whether the work is safe and structurally sound, covering matters such as structure, fire safety, insulation, drainage and electrics. A property can meet one and not the other, so ask about both.

Documents to Ask For

• Planning permission decision notice or, where relied upon, a lawful development certificate for permitted development.
• Building regulations completion certificate from the local authority or an approved inspector.
• Electrical and gas safety documents for relevant works, such as a certificate from a registered installer.
• Structural engineer's calculations where a load-bearing wall was removed.
• Warranty or insurance for the work, if any.

Your solicitor can also check local authority records through the property searches. See our guide to UK property searches explained.

What if the Paperwork Is Missing?

Options depend on the work and the age of it. They can include asking the seller to obtain retrospective approval, an indemnity insurance policy, a price reduction, or walking away. Indemnity insurance does not fix the underlying work, and lenders have their own views, so ask your solicitor and mortgage lender before relying on it. Our guide on what to do if a lender values below the price explains how lender checks can affect a purchase.

Flats and Leasehold Properties

In a leasehold flat, alterations also usually need the freeholder's consent under the lease. Ask whether consent was given for any internal changes, and read the lease terms. See freehold, leasehold and share of freehold.

Use a Survey

A survey can show signs of poor work, such as cracking, damp or unusual structural changes. See our guide to RICS survey levels for how to choose one.

Buying From Abroad

Overseas buyers cannot easily inspect work in person, so rely on a solicitor, a survey and written documents. Our guide to choosing a conveyancing solicitor when buying from abroad covers what to ask.

Common Mistakes

• Assuming an extension is fine because it looks well built.
• Relying on the seller's word instead of paperwork.
• Treating planning permission and building regulations as the same thing.
• Forgetting freeholder consent for leasehold alterations.

Talk to Banke UK

To discuss a UK purchase, contact the Banke UK team. We are not a law firm, so legal checks should be carried out by your solicitor.

Conclusion

Ask for planning and building regulations documents for any altered property, check lease consents for flats, and let your solicitor and surveyor test the answers before you exchange contracts. This is general information, not legal, tax or financial advice. Rules, fees and procedures change, so confirm current details with the relevant authority or a qualified professional before you commit money.