Extension rules for London homes
We design and build extensions across Greater London. These are the permitted development limits we check first.
Extensions across all London boroughs
We take on extension projects throughout Greater London.
Side-return extensions suit many Victorian terraces, while 1930s semis often suit wide rear or wraparound designs. Conservation areas and listed buildings, which are found across London, usually need a planning application and a careful choice of materials.
Each London borough is its own planning authority, so we can tell you which council you’ll be dealing with for your address and what that is likely to mean for your project.
We visit your home to discuss the extension, wherever you are in London.
London boroughs we cover
Barking and Dagenham · Barnet · Bexley · Brent · Bromley · Camden · City of London · Croydon · Ealing · Enfield · Greenwich · Hackney · Hammersmith and Fulham · Haringey · Harrow · Havering · Hillingdon · Hounslow · Islington · Kensington and Chelsea · Kingston upon Thames · Lambeth · Lewisham · Merton · Newham · Redbridge · Richmond upon Thames · Southwark · Sutton · Tower Hamlets · Waltham Forest · Wandsworth · Westminster
Side and wraparound extensions
A side extension under permitted development can only be single storey, up to 4 metres high and no more than half the width of the original house. In conservation areas, all side extensions need householder planning permission. [1]
Double-storey extensions
A rear extension of more than one storey cannot extend more than 3 metres beyond the original rear wall, or be within 7 metres of the rear boundary. In conservation areas, it always needs planning permission. [1]
How common conservation areas are
About 20.3% of London’s homes (around 710,000) are in one of 1,056 conservation areas, according to Historic England, so many London extensions need a full planning application. [2]
Sources and further reading
- Planning Portal, Extensions: planning permission
- Historic England, Profiling Energy Use in London’s Conservation Areas
Last checked: 15 October 2026. Not legal or planning advice. Rules can change, so confirm with your borough.
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