The permitted development rules for loft conversions
A loft conversion with a rear dormer is permitted development on a house if the added roof volume is no more than 40 m³ on a terraced house or 50 m³ on a semi-detached or detached house, the dormer sits at least 200 mm back from the eaves and no higher than the ridge, there is no dormer on the roof slope facing the road, materials are similar in appearance, and side windows are obscure-glazed.
Flats and maisonettes have no permitted development rights, so a loft to a top-floor flat always needs planning permission. Full-width box dormers that reach the ridge, and hip-to-gable conversions on semis whose volume exceeds 50 m³, also fall outside the allowance.
What changes in Ealing
Roof extensions are not permitted development in a conservation area, so a dormer or hip-to-gable there needs a householder planning application designed to the area's appraisal.
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.
