Side extensions in Kingston upon Thames depend on the house. Typical homes here: 1930s semis and bungalows in New Malden, Tolworth, Chessington and Old Malden; Victorian and Edwardian terraces in Norbiton, Surbiton and Kingston town. Designations to check first: Conservation areas; Thames and Hogsmill flood zones; Green Belt and Metropolitan Open Land. Applications are decided by Royal Borough of Kingston upon Thames.
The permitted development rules for side extensions
A single-storey side extension is permitted development on a house if it is no wider than half the width of the original house, no higher than 4 m, with eaves no higher than 3 m where it comes within 2 m of a boundary, and finished in materials similar in appearance to the house.
Anything wider than half the original house, any two-storey side extension, and any side extension on a flat needs planning permission. Garage conversions that keep the walls are usually permitted development; extending beyond them is assessed as a side extension.
What changes in Kingston upon Thames
Side extensions are not permitted development in a conservation area at all, so there a planning application is always required.
The local constraints that most often decide the route in Kingston upon Thames are listed below, taken from our Kingston upon Thames area page. Each one is a reason to confirm the address on Kingston upon Thames' constraints map before relying on permitted development.
- Conservation areas. Kingston has numerous conservation areas, including Kingston Old Town, Surbiton's Southborough and Oakhill areas, Coombe and parts of New Malden. Source
- Thames and Hogsmill flood zones. Land along the Thames at Kingston and Canbury and along the Hogsmill through Old Malden, Berrylands and Kingston falls within Flood Zones 2 and 3. Source
- Green Belt and Metropolitan Open Land. Chessington, Hook and the southern edge of the borough include Green Belt, and there is Metropolitan Open Land along the Hogsmill and around Richmond Park.
- Article 4 directions. Some Kingston conservation areas are understood to carry Article 4 directions removing permitted development for front alterations and boundary treatments.
What Kingston upon Thames planning officers look for
Side extensions that close the gap between semis, are not set back from the front wall or carry a roof up to the main ridge are a frequent refusal reason, as are two-storey rear extensions that breach the 45-degree rule to neighbours. Roof extensions in conservation areas and front dormers anywhere attract resistance. Pre-application advice is available for a fee.
Fees and timelines
Kingston upon Thames 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.
- Royal Borough of Kingston upon Thames: planning: the council's own constraints map, validation checklist and pre-application service.
