Side extensions in Croydon depend on the house. Typical homes here: Victorian and Edwardian terraces in Addiscombe, South Norwood, Thornton Heath and Selhurst; 1930s semi-detached houses in Purley, Shirley, Coulsdon, Sanderstead and Selsdon. Designations to check first: Conservation areas and Local Areas of Special Character; Green Belt and Metropolitan Open Land; Article 4 directions. Applications are decided by London Borough of Croydon and the Croydon Local Plan (2018).
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 Croydon
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 Croydon are listed below, taken from our Croydon area page. Each one is a reason to confirm the address on Croydon's constraints map before relying on permitted development.
- Conservation areas and Local Areas of Special Character. Croydon has numerous conservation areas, including the Webb Estate, Chatsworth Road, Church Street, Norwood Grove and Bradmore Green, plus Local Areas of Special Character identified in the Local Plan. Source
- Green Belt and Metropolitan Open Land. The southern third of the borough, including Coulsdon, Kenley, Sanderstead, Selsdon and Addington, contains extensive Green Belt and Metropolitan Open Land. Source
- Article 4 directions. Croydon has Article 4 directions in several conservation areas, including the Webb Estate, removing permitted development for front alterations, boundary treatments and some roof works. Source
- Flood risk: Wandle and surface water. The River Wandle rises in Croydon and parts of Waddon, Beddington borders and the town centre carry fluvial or surface-water flood risk. Source
What Croydon planning officers look for
Refusals most often cite two-storey side extensions without a set-back that create a terracing effect, rear extensions that breach the 45-degree line, oversized rear dormers that wrap the hip, and any loss of gaps between houses in Local Areas of Special Character. Pre-application advice is available for a fee, and decision times often exceed the statutory 8 weeks; allow 10–14 weeks.
Fees and timelines
Croydon 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 Croydon: planning: the council's own constraints map, validation checklist and pre-application service.
