Do I need planning permission for an extension?
Permitted development or full planning? A plain-English guide to when a home extension needs planning permission in England.
It's the first question almost every homeowner asks, and the honest answer is "it depends, but often less than you'd think." Here's how it works in England. Always confirm for your specific property, rules change and exceptions are common. We'll check for free at your first visit.
Two routes: permitted development vs full planning
Many home extensions and conversions can be done under permitted development (PD), national rights that let you build certain things without a full planning application, as long as you stay within set limits. Anything beyond those limits needs full (householder) planning permission from your local council.
What PD generally covers
- Single-storey rear extensions within set depth and height limits.
- Some two-storey rear extensions within tighter limits.
- Loft conversions within a volume allowance (with rules on dormers and materials).
- Garage conversions (internal), and many outbuildings.
When you'll usually need full planning permission
- Extending beyond the PD size, height or coverage limits.
- Building forward of the principal elevation (towards the road).
- Homes where PD rights are restricted, flats and maisonettes, listed buildings, many conservation areas, and properties with an Article 4 direction (common in Cambridge and Letchworth).
- Anything affecting a shared boundary that also triggers Party Wall procedures.
A note on building regulations
Planning permission and building regulations are different things. Even when an extension is permitted development and needs no planning application, it will still need to meet building regulations, which is where building-regs drawings and structural calculations come in.
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