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 Ealing
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 Ealing are listed below, taken from our Ealing area page. Each one is a reason to confirm the address on Ealing's constraints map before relying on permitted development.
- Conservation areas. Ealing has numerous conservation areas, including Brentham Garden Suburb, Bedford Park (shared with Hounslow), Ealing Common, Ealing Town Centre, Hanger Hill Garden Estate, Haven Green and Hanwell Village Green. Roof extensions are not permitted development inside them and each has a management plan officers apply. Source
- Article 4 directions in garden suburbs and estates. Brentham Garden Suburb, Bedford Park and the Hanger Hill Garden Estate, among others, have Article 4 directions removing permitted development for external alterations, so most changes need planning permission. Check the council's constraints map for your street. Source
- Flood risk – River Brent and Grand Union Canal. The River Brent through Hanwell, Perivale and Greenford, and the Grand Union Canal through Southall and Alperton borders, place some streets in Flood Zones 2 and 3. Ground-floor extensions there may need a flood risk statement. Source
- Green Belt and Metropolitan Open Land. Northolt, Horsenden Hill, Perivale Park and the Brent River Park include Green Belt and Metropolitan Open Land. Plots on their edge face stricter tests for outbuildings and larger extensions. Source
- HMO Article 4 direction. Ealing may operate an Article 4 direction requiring planning permission to convert a house into a small house in multiple occupation (HMO). We are not certain of its current extent, so confirm with the council before letting rooms. Source
What Ealing planning officers look for
Ealing officers apply the residential extensions guidance closely. Common refusal reasons are two-storey side extensions without a set-back from the front wall, rear extensions that fail the 45-degree test, and roof extensions in conservation areas that do not match the existing pattern. On the 1930s semis of Greenford and Perivale, hip-to-gable lofts and 4–6 m rear extensions are usually accepted. The council offers a paid pre-application service, which we recommend for Brentham, Bedford Park and Hanger Hill. Decisions often run past 8 weeks; allow 10–14 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.
