Side extensions in Enfield depend on the house. Typical homes here: 1930s semi-detached houses in Southgate, Oakwood, Winchmore Hill, Enfield Town suburbs and Edmonton; Victorian and Edwardian terraces in Palmers Green, Bowes Park, Edmonton and Ponders End. Designations to check first: Green Belt; Lee Valley flood risk; Conservation areas. Applications are decided by London Borough of Enfield and the Enfield Local Plan (Core Strategy 2010 and Development Management Document 2014).
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 Enfield
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 Enfield are listed below, taken from our Enfield area page. Each one is a reason to confirm the address on Enfield's constraints map before relying on permitted development.
- Green Belt. Enfield has one of the largest Green Belt areas of any London borough, covering Crews Hill, Botany Bay, Forty Hill, Whitewebbs, Trent Park and the fringes of Enfield Chase. Source
- Lee Valley flood risk. The eastern edge of the borough along the River Lee and its tributaries (Salmons Brook, Pymmes Brook, Turkey Brook) sits in Flood Zones 2 and 3, affecting parts of Edmonton, Ponders End, Enfield Lock and Brimsdown. Source
- Conservation areas. Enfield has numerous conservation areas, including Enfield Town, Forty Hill, Bush Hill Park, Winchmore Hill Green, Southgate Green, the Lakes Estate and Trent Park. Source
- Article 4 directions. Several Enfield conservation areas, including Bush Hill Park and the Lakes Estate, have Article 4 directions removing permitted development for front alterations, boundary walls and some roof works. Source
What Enfield planning officers look for
Enfield officers are, in our experience, reasonable on suburban householder work but firm on set-backs and the 45-degree test. Common refusal reasons are two-storey side extensions flush with the front wall that create a terracing effect, rear extensions deeper than the neighbour's, front dormers, and box dormers that wrap the hip. The council offers a paid pre-application service and decisions often run beyond 8 weeks, so allow 10–14 weeks.
Fees and timelines
Enfield 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 Enfield: planning: the council's own constraints map, validation checklist and pre-application service.
