Do You Need Planning Permission for an Extension?

Good news: a lot of extensions don’t need full planning permission at all. Many fall under Permitted Development, which lets you extend within set limits without a formal application. But there are rules, and getting them wrong is expensive.

Permitted Development, roughly

For a single-storey rear extension you can usually go up to 4m for a detached house and 3m for a semi or terrace, within height and footprint limits. Side extensions and two-storey extensions have their own rules. It’s sensible to apply for a Lawful Development Certificate so you’ve got proof it was allowed.

When you do need permission

• You’re going beyond the Permitted Development size limits.
• Your home is listed or in a conservation area.
• Permitted Development rights have been removed (common on newer estates).
• You’re building to the front, or significantly altering the roof.

Don’t forget Building Regulations

This is the bit people mix up. Even when you don’t need planning permission, your extension almost always needs Building Regulations approval — that’s what covers structure, insulation, drainage and safety. They’re two different things.

It sounds like a lot, but you don’t have to manage any of it yourself. We handle the drawings, structural calculations, Building Control and any planning application as part of the job, so you’ve got one point of contact throughout.

We handle home extensions across Sleaford, Lincoln, Grantham and the wider Lincolnshire area — see our services →