Do I need planning permission for my extension or loft?
Answer a few quick questions to see whether your project could be permitted development, based on England's national rules and notes for your borough. It takes under a minute. Ready to go further? Meet our house extension and loft conversion architects.
Borough planning guides
Do I need planning permission in Barnet?
Covers Golders Green, Finchley, Hendon and Hampstead Garden Suburb.
Barnet has Article 4 directions that remove householder permitted development rights on named streets in some conservation areas, for example parts of Hendon The Burroughs. Check your address in Barnet's Article 4 records.
In Hampstead Garden Suburb, changes to the outside of a house need the prior approval of the Hampstead Garden Suburb Trust, and the Suburb is a conservation area, so Barnet's approval is also needed for alterations.
Barnet and the Trust publish joint design guidance for the Suburb covering extensions, lofts, dormers and basements.
Source: Barnet Council and the Hampstead Garden Suburb Trust, checked 8 November 2026. Article 4 areas are often street-specific, so check your exact address on the council's website.
Do I need planning permission in Camden?
Covers Hampstead, Belsize Park, Kentish Town and Camden Town.
Camden's Home Improvements planning guidance (January 2021) sets out what it expects from rear, side and roof extensions, dormers and new roof levels.
Camden's Basements guidance (January 2021) requires a basement impact assessment and refers to an Article 4 direction for basement development.
Source: Camden Council, checked 8 November 2026. Article 4 areas are often street-specific, so check your exact address on the council's website.
Do I need planning permission in Haringey?
Covers Muswell Hill, Crouch End and Highgate.
Haringey uses Article 4 directions in conservation areas to control small changes such as windows and doors. Where one applies, planning permission is needed for those works.
Haringey lists the works that need planning permission in a conservation area on its website.
Source: Brent Council, checked 8 November 2026. Article 4 areas are often street-specific, so check your exact address on the council's website.
Do I need planning permission in Harrow?
Covers Stanmore, Pinner and Harrow on the Hill.
Harrow has Article 4 directions in its conservation areas, including Harrow on the Hill, which mean planning permission is needed for works that would otherwise be permitted.
Harrow's Residential Design guidance sets out what it expects from extensions and dormers.
Source: Harrow Council, checked 8 November 2026. Article 4 areas are often street-specific, so check your exact address on the council's website.
Do I need planning permission in Westminster?
Covers St John's Wood, Maida Vale and Marylebone.
Westminster has Article 4 directions removing some permitted development rights in parts of the borough, and has removed them in eight conservation areas, where planning permission is needed for specified minor changes.
How deep can a rear extension be without planning permission?
Under permitted development, a single-storey rear extension can be up to 3m deep on a terraced or semi-detached house and 4m on a detached house. With prior approval from the council this rises to 6m and 8m. These limits don't apply to flats, and conservation areas have extra restrictions.
Do loft conversions need planning permission?
Often not. A loft conversion can be permitted development if it adds no more than 40m³ on a terraced house or 50m³ on other houses, with no dormer facing the street. It isn't permitted development in a conservation area.
Should I get a Certificate of Lawfulness?
It's optional, but it confirms in writing that your work is permitted development. That helps when you sell, and it gives you peace of mind before building.
