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 Barking and Dagenham
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 Barking and Dagenham are listed below, taken from our Barking and Dagenham area page. Each one is a reason to confirm the address on Barking and Dagenham's constraints map before relying on permitted development.
- Conservation areas. Barking and Dagenham has only a small number of conservation areas, centred on Barking Abbey and the town centre and a handful of historic pockets. Inside them, roof extensions are not PD and side or rear extensions face a stricter design test. Source
- Flood risk – Thames, Roding and Beam. Land along the Thames (Barking Riverside, Thames View, Creekmouth), the River Roding and the Beam River sits in Flood Zones 2 and 3. Extensions and basements here may need a flood risk assessment. Check the Environment Agency flood map for your postcode. Source
- Green Belt and Metropolitan Open Land. Eastbrookend Country Park, The Chase and the Dagenham corridor include Green Belt and Metropolitan Open Land, where outbuildings and larger extensions face a much higher bar. We confirm the designation of your plot before drawing. Source
- Article 4 directions. We are not aware of a borough-wide Article 4 direction removing householder PD rights, but the council may have made directions on specific estates or for houses in multiple occupation (HMOs). Always confirm on the council's constraints map or with a Lawful Development Certificate before building under PD. Source
What Barking and Dagenham planning officers look for
Barking and Dagenham is, in our experience, a pragmatic authority for householder work. Officers focus on depth of rear extensions relative to the neighbour (the 45-degree test), the height and bulk of rear dormers, and keeping front elevations on the Becontree estate intact. Common refusal reasons are over-deep single-storey extensions that box in a neighbour's kitchen window, and loft dormers that run almost the full width of the roof. The council generally offers a paid pre-application service, which we recommend for anything in a conservation area or on a corner plot. Decision times usually sit close to the statutory 8 weeks but can run longer.
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.
