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 Haringey
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 Haringey are listed below, taken from our Haringey area page. Each one is a reason to confirm the address on Haringey's constraints map before relying on permitted development.
- Conservation areas. Haringey has around 29 conservation areas, including Highgate, Muswell Hill, Crouch End, Alexandra Palace and Park, Rookfield, Noel Park, Tower Gardens, Bruce Castle and Tottenham Green. Roof extensions are not permitted development inside them, and Noel Park and Tower Gardens have particularly detailed appraisals covering windows, porches and boundary walls. Source
- Article 4 direction on HMOs. Haringey has an Article 4 direction removing permitted development for changing a house (Class C3) into a small house in multiple occupation (Class C4). We understand it applies across the borough, so any new HMO needs a planning application as well as a licence. Check the council's constraints map and licensing pages before buying with an HMO in mind. Source
- Article 4 directions in conservation areas. Several conservation areas, including Noel Park, Tower Gardens, Rookfield and parts of Highgate and Muswell Hill, have Article 4 directions removing permitted development for front alterations, windows, boundary treatments and some roof works. Check the constraints map before relying on permitted development. Source
- Lee Valley flood risk. Tottenham Hale, Northumberland Park, the Tottenham Marshes edge and land along the Moselle and Pymmes Brooks sit in Flood Zones 2 and 3. Ground-floor extensions and basements there may need a flood risk statement. Source
- Listed buildings. Highgate village, Bruce Castle, Tottenham High Road and Tottenham Green contain concentrations of listed buildings. Listed building consent is needed for almost any alteration, internal or external. Source
What Haringey planning officers look for
Haringey officers are protective of the unbroken rear elevations and rooflines of the Ladder and Tottenham terraces, and of the Edwardian roofscapes of Muswell Hill and Crouch End. Common refusal reasons are rear extensions that fail the 45-degree test, full-width box dormers, dormers that wrap a hipped roof, front dormers and roof extensions in conservation areas. Outside conservation areas a rear dormer within 40 m³ and a 3 m or 6 m rear extension are routinely lawful. The council offers paid pre-application advice and decisions frequently run beyond 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.
