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 Redbridge
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 Redbridge are listed below, taken from our Redbridge area page. Each one is a reason to confirm the address on Redbridge's constraints map before relying on permitted development.
- Green Belt. The north and east of the borough, including Hainault Forest, Fairlop Waters, Claybury and land around Woodford Bridge, is Green Belt. Extensions to houses in the Green Belt must not be disproportionate to the original dwelling, and outbuildings face a strict test on size and siting. Source
- Conservation areas. Redbridge's conservation areas are concentrated in Wanstead and Woodford, including Wanstead Village, Woodford Bridge and Monkhams. Roof extensions are not permitted development inside them, and officers apply the character appraisal to extensions and dormers. Check the council's constraints map for the exact boundaries before relying on permitted development. Source
- Article 4 direction on HMOs. Redbridge has used an Article 4 direction to remove permitted development for converting a house into a small house in multiple occupation (C3 to C4), so HMO conversions normally need planning permission. Check the constraints map for any further directions affecting front alterations or roof works in conservation areas. Source
- River Roding flood risk. The River Roding runs the length of the borough from Woodford Bridge through Wanstead and Ilford, and land alongside it sits in Flood Zones 2 and 3. Ground-floor extensions and basements there may need a flood risk statement with the application. Source
- Epping Forest land. Wanstead Flats, Wanstead Park and the Forest land in Snaresbrook and Woodford are protected open space within the Epping Forest Special Area of Conservation. Houses backing onto the Forest can face additional requirements; raise it with the council early. Source
- Listed buildings. Wanstead, Woodford and the older centres of Ilford and Barkingside contain listed houses and churches. Listed building consent is needed for almost any alteration, internal or external. Source
What Redbridge planning officers look for
Redbridge officers assess householder applications against the Local Plan and the council's supplementary guidance on residential extensions. On the 1930s semis that dominate the borough they look for two-storey side extensions set back from the front wall and below the main ridge, a gap kept to the side boundary so the pair does not read as a terrace, rear extensions that pass the 45-degree test to the neighbour's nearest habitable window, and hipped roofs kept where a gable would unbalance the pair. Common refusal reasons are full-width box dormers, side extensions that create a terracing effect, and roof extensions on front slopes in conservation areas. Outside conservation areas, hip-to-gable and rear-dormer lofts within 50 m³ on a semi are routinely lawful and we secure a Lawful Development Certificate as proof. Redbridge offers a paid pre-application service. Decisions can run past the statutory 8 weeks; allow 8–12 weeks.
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.
