The permitted development rules for two-storey extensions
A two-storey rear extension is permitted development only within tight limits: no more than 3 m deep, at least 7 m from the rear boundary, no higher than the existing house, eaves matching the existing eaves, materials similar in appearance, and any upper-floor side window obscure-glazed and non-opening below 1.7 m.
Most two-storey extensions exceed one of those limits, most often the 7 m rear boundary rule on London plots, so the usual route is a householder planning application. Flats have no permitted development rights.
What changes in Kingston upon Thames
Extensions of more than one storey are not permitted development in a conservation area, so planning permission is always needed there.
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's 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. Roof extensions and cladding in these areas need planning permission. Check the council's constraints map for your address before relying on permitted development. 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. Basements and new ground-floor habitable rooms may need a flood risk assessment even for a householder application. 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. Extensions and outbuildings to houses within or adjoining these areas are judged on openness and are often limited in size.
- Article 4 directions. Some Kingston conservation areas are understood to carry Article 4 directions removing permitted development for front alterations and boundary treatments. Coverage varies by area, so we confirm with the council before recommending a permitted development route.
What Kingston upon Thames planning officers look for
Kingston is a predominantly suburban borough and its officers pay close attention to the character of 1930s streets. 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. Single-storey rear extensions of 3 to 4 m are generally acceptable. Roof extensions in conservation areas and front dormers anywhere attract resistance. Pre-application advice is available for a fee.
Fees and timelines
The council fee for a householder application is £528 and for a Lawful Development Certificate £264 (England, from 1 April 2025; verify before applying). Both are decided within 8 weeks of validation.
Our own fee for the drawings and the application is fixed once quoted and depends on the project type, its size and the constraints above. Answer six questions in the quote tool and we email you an indicative figure within minutes, then a written fixed-fee quote within 24 hours.
