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Planning permission for extensions
Updated October 2026
Many extensions in England can be built under permitted development rights without a full planning application, as long as they meet size and design limits. Wales, Scotland and Northern Ireland have their own rules.
When you usually need planning permission
- The extension goes beyond the permitted development size limits
- The home is a flat or maisonette (permitted development doesn't apply)
- The property is listed, or in a conservation area or national park, where rules are stricter
- Permitted development rights have been removed for your property
Building regulations
Almost all extensions need building regulations approval, whether or not they need planning permission. This covers structure, insulation, fire safety, drainage and ventilation.
Party walls
Building on or near a shared wall or boundary may mean serving a party wall notice on your neighbours. Get advice early.
Check before you start
Use the Planning Portal's interactive guides, or ask your council for a lawful development certificate if you want written confirmation your project doesn't need planning permission.
Need help?
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