Rear extensions in Southwark depend on the house. Typical homes here: Georgian and early Victorian terraces in Camberwell, Walworth and Kennington Park; Victorian terraces in Peckham, Nunhead, Camberwell and East Dulwich. Designations to check first: Conservation areas; Article 4 directions; Thames flood zones. Applications are decided by London Borough of Southwark and the Southwark Plan 2022.
The permitted development rules for rear extensions
On a house, a single-storey rear extension is permitted development if it projects no more than 3 m from the original rear wall on a terraced or semi-detached house, or 4 m on a detached house, is no higher than 4 m, has eaves no higher than 3 m where it comes within 2 m of a boundary, and uses materials similar in appearance to the house. The larger home extension route allows 6 m or 8 m through a 42-day prior approval, where the council consults the neighbours.
Flats and maisonettes have no householder permitted development rights, so any rear extension to a flat needs planning permission. Previous extensions count against the allowance, and the larger home extension route is not available in conservation areas.
What changes in Southwark
In a conservation area a single-storey rear extension can still be permitted development within the 3 m or 4 m limit, but cladding it in materials that differ from the house is not, and the 6 m and 8 m prior approval route is closed.
The local constraints that most often decide the route in Southwark are listed below, taken from our Southwark area page. Each one is a reason to confirm the address on Southwark's constraints map before relying on permitted development.
- Conservation areas. Southwark has numerous conservation areas, concentrated in Camberwell, Dulwich, Peckham Rye, Nunhead, Bermondsey Street and Borough. Source
- Article 4 directions. Southwark has Article 4 directions in several conservation areas removing permitted development for front alterations and boundary treatments, and a Class MA Article 4 covering the Central Activities Zone and town centres that removes the commercial-to-residential prior approval route.
- Thames flood zones. Bermondsey, Rotherhithe, Borough and the riverside fall within Flood Zones 2 and 3, protected by the Thames Barrier and river walls. Source
- Listed buildings and Metropolitan Open Land. Camberwell, Dulwich Village, Borough and Bermondsey Street contain many listed buildings needing listed building consent for alterations.
What Southwark planning officers look for
Rear extensions deeper than neighbouring precedent, side returns that breach the 45-degree rule and roof extensions in conservation areas are the common refusal reasons; front dormers are resisted almost everywhere. Pre-application advice is available for a fee.
Fees and timelines
Southwark decides a householder application or a Lawful Development Certificate within 8 weeks of validation. The council fee is £528 for a householder application and £264 for a Lawful Development Certificate (England, from 1 April 2025; verify before applying).
Our own fee is fixed once quoted. The quote tool gives an indicative figure in minutes and a written quote follows within 24 hours.
Primary sources
- The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2: the permitted development limits quoted above.
- Planning Portal: do you need permission: the national guidance and the application service every council accepts.
- London Borough of Southwark: planning: the council's own constraints map, validation checklist and pre-application service.
