Rear extensions in Sutton depend on the house. Typical homes here: 1930s semis and chalet bungalows in Cheam, Worcester Park, Wallington and Carshalton; Victorian and Edwardian terraces and villas in Carshalton, Sutton town and Wallington. Designations to check first: Conservation areas; Article 4 directions; River Wandle flood zones. Applications are decided by London Borough of Sutton and the Sutton Local Plan 2018.
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 Sutton
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 Sutton are listed below, taken from our Sutton area page. Each one is a reason to confirm the address on Sutton's constraints map before relying on permitted development.
- Conservation areas. Sutton has numerous conservation areas, including Carshalton Village, Cheam Village, Sutton Garden Suburb and parts of Wallington and Beddington. Source
- Article 4 directions. Some Sutton conservation areas, including Sutton Garden Suburb and parts of Carshalton, are understood to carry Article 4 directions removing permitted development for front alterations and boundary treatments.
- River Wandle flood zones. The Wandle rises at Carshalton Ponds and runs north through Carshalton, Hackbridge and Beddington. Source
- Green Belt and Metropolitan Open Land. The southern edge of the borough at Little Woodcote, Woodmansterne and Belmont includes Green Belt, and Beddington Park, Roundshaw Downs and other open spaces are Metropolitan Open Land.
- Trees and tree preservation orders. Sutton's suburban streets and larger plots carry many protected trees.
What Sutton planning officers look for
Side extensions that close the gap between semis, are flush with the front wall or carry a roof up to the main ridge are the most common refusal reason. Single-storey rear extensions of 3 to 4 m are generally acceptable; two-storey rear extensions are judged closely against the 45-degree rule and neighbours' outlook. Hip-to-gable lofts with rear dormers are routinely accepted outside conservation areas. Pre-application advice is available for a fee.
Fees and timelines
Sutton 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 Sutton: planning: the council's own constraints map, validation checklist and pre-application service.
