Two-storey extensions in Bromley depend on the house. Typical homes here: 1930s semi-detached houses in Orpington, West Wickham, Hayes, Bromley Common and Mottingham; Edwardian and interwar detached houses in Bickley, Chislehurst, Petts Wood and Sundridge Park. Designations to check first: Conservation areas; Green Belt and Metropolitan Open Land; Article 4 directions. Applications are decided by London Borough of Bromley and the Bromley Local Plan (2019).
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 Bromley
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 Bromley are listed below, taken from our Bromley area page. Each one is a reason to confirm the address on Bromley's constraints map before relying on permitted development.
- Conservation areas. Bromley has numerous conservation areas, including Chislehurst, Petts Wood, Bickley Park, Beckenham Place, Sundridge Park, Keston and several around Bromley town centre. Source
- Green Belt and Metropolitan Open Land. Roughly half of the borough is Green Belt or Metropolitan Open Land, taking in Keston, Downe, Cudham, Biggin Hill, Chelsfield and Pratts Bottom. Source
- Article 4 directions. Several Bromley conservation areas, including parts of Chislehurst and Petts Wood, have Article 4 directions removing permitted development for front-facing alterations, boundary treatments or roof works. Source
- Flood risk: Ravensbourne, Cray and Beck. The River Ravensbourne, Cray, Beck and Pool River corridors through Beckenham, Shortlands, Bromley and St Mary Cray carry fluvial flood risk. Source
What Bromley planning officers look for
Refusals most often cite two-storey side extensions that close the gap between houses or lack a set-back, rear extensions that breach the 45-degree line to a neighbour, and roof extensions in conservation areas or Areas of Special Residential Character. The council generally offers a paid pre-application service; decisions often run beyond 8 weeks, so allow 10–14 weeks.
Fees and timelines
Bromley 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 Bromley: planning: the council's own constraints map, validation checklist and pre-application service.
