Rear extensions in Lewisham depend on the house. Typical homes here: Georgian and Regency houses and terraces in Blackheath and around Blackheath Village; Victorian terraces and villas in Brockley, Ladywell, Hither Green, Lee and New Cross. Designations to check first: Conservation areas; Article 4 directions; Ravensbourne, Quaggy and Pool river flood zones. Applications are decided by London Borough of Lewisham.
The permitted development rules for rear extensions
On a house, a single-storey rear extension is permitted development if it projects no more than 3 m from the original rear wall on a terraced or semi-detached house, or 4 m on a detached house, is no higher than 4 m, has eaves no higher than 3 m where it comes within 2 m of a boundary, and uses materials similar in appearance to the house. The larger home extension route allows 6 m or 8 m through a 42-day prior approval, where the council consults the neighbours.
Flats and maisonettes have no householder permitted development rights, so any rear extension to a flat needs planning permission. Previous extensions count against the allowance, and the larger home extension route is not available in conservation areas.
What changes in Lewisham
In a conservation area a single-storey rear extension can still be permitted development within the 3 m or 4 m limit, but cladding it in materials that differ from the house is not, and the 6 m and 8 m prior approval route is closed.
The local constraints that most often decide the route in Lewisham are listed below, taken from our Lewisham area page. Each one is a reason to confirm the address on Lewisham's constraints map before relying on permitted development.
- Conservation areas. Lewisham has numerous conservation areas, including large ones at Brockley and Blackheath and others in Forest Hill, Sydenham, Lee Manor, Telegraph Hill and Deptford. Source
- Article 4 directions. The Brockley conservation area and some others in Lewisham carry Article 4 directions removing permitted development for front alterations, windows, roofs and boundary treatments.
- Ravensbourne, Quaggy and Pool river flood zones. The Ravensbourne, Quaggy and Pool rivers run through Catford, Lewisham town centre, Ladywell, Lee and Bellingham, and land along them falls within Flood Zones 2 and 3. Source
- Listed buildings in Blackheath and Deptford. Blackheath, Blackheath Park, Deptford High Street and St Paul's Deptford contain many listed Georgian and Victorian buildings.
- Metropolitan Open Land. Blackheath, Hilly Fields, Beckenham Place Park, Mountsfield Park and the Waterlink Way corridor are Metropolitan Open Land.
What Lewisham planning officers look for
Rear extensions deeper than neighbouring precedent, side returns that breach the 45-degree rule and roof extensions in Brockley, Blackheath and other conservation areas are the common refusal reasons; front dormers are resisted almost everywhere. Pre-application advice is available for a fee.
Fees and timelines
Lewisham decides a householder application or a Lawful Development Certificate within 8 weeks of validation. The council fee is £528 for a householder application and £264 for a Lawful Development Certificate (England, from 1 April 2025; verify before applying).
Our own fee is fixed once quoted. The quote tool gives an indicative figure in minutes and a written quote follows within 24 hours.
Primary sources
- The Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2: the permitted development limits quoted above.
- Planning Portal: do you need permission: the national guidance and the application service every council accepts.
- London Borough of Lewisham: planning: the council's own constraints map, validation checklist and pre-application service.
