Permitted development extensions: what can you build without planning?

What is permitted development?

Permitted development rights let you make certain changes to a house without applying for planning permission, as long as you stay within set size limits. They apply to houses, not flats or maisonettes, and they can be removed in some places, so it's always worth checking first.

Single-storey rear extensions

• Up to 3 m deep on a semi-detached or terraced house, or 4 m on a detached house, measured from the original rear wall
• No higher than 4 m
• If within 2 m of a boundary, the eaves can't be higher than 3 m

Under the larger home extension scheme you can go up to 6 m (semi or terrace) or 8 m (detached). You notify the council, neighbours get 21 days to comment, and the council only looks at the effect on neighbours if someone objects.

Side extensions

• Single storey only, with a maximum height of 4 m
• No wider than half the width of the original house
• Not allowed beyond a side wall that faces a road

Two-storey rear extensions

• No more than 3 m deep
• At least 7 m from the rear boundary
• Upper-floor side windows must be obscure-glazed and fixed shut below 1.7 m
• The roof pitch should match the house as far as practical

Rules that apply to every extension

• Extensions and outbuildings together can't cover more than half the land around the original house. Earlier extensions count.
• No extension can go forward of the front of the house facing a road.
• "Original house" means as first built, or as it stood on 1 July 1948, so previous extensions use up some of your allowance.

When you still need planning permission

• In conservation areas, National Landscapes (like the North Devon Coast) and National Parks, side and two-storey extensions aren't permitted development, and the larger home extension scheme isn't available
• Listed buildings need listed building consent
• Where the council has removed permitted development rights, for example by a planning condition or an Article 4 direction

Two things people often miss

Building regulations still apply. Permitted development only covers planning. Every extension still needs building regulations approval for structure, insulation, drainage and fire safety.

Get a Lawful Development Certificate. It's an optional application to the council confirming your extension is permitted development. It costs much less than planning, and gives you proof when you come to sell.

Planning an extension?

We can check what your house allows, handle the drawings and building regulations, and build it. These rules are a simplified summary for England, so always check the details for your property. More on our extensions.