How deep can I extend without planning permission?

Three metres from the original rear wall on a terraced or semi-detached house and four metres on a detached house, under Class A permitted development. Six or eight metres is possible through the larger home extension prior approval, a 42-day process with a £120 fee, outside conservation areas.

Do I need a Lawful Development Certificate if the extension is permitted development?

Not legally, but we recommend one. It is the council's formal confirmation that the extension is lawful, which lenders, buyers and solicitors routinely ask for. The fee is £264 and the decision takes up to 8 weeks.

What if my neighbour has already extended?

Their extension does not change your rights, but it does shape what the council will accept if you need planning permission: officers compare depth and height against the neighbouring extension and apply the 45-degree daylight test from the nearest habitable window.

How long does Epsom and Ewell take to decide?

The statutory period is 8 weeks from validation for both a householder application and a Lawful Development Certificate, and 42 days for a larger home extension prior approval. Decisions can run past the statutory 8 weeks; allow 8–12 weeks.

Rear Extensions in Epsom and Ewell: Planning

Rear extensions in Epsom and Ewell depend on the house. Typical homes here: 1930s semi-detached houses in Stoneleigh, West Ewell, Ewell and the Epsom and Ewell part of Worcester Park; Edwardian and inter-war detached houses in Woodcote and around Epsom Downs. Designations to check first: Green Belt; Conservation areas; Hogsmill River flood risk. Applications are decided by Epsom and Ewell Borough Council and the Epsom and Ewell Core Strategy 2007 (new Local Plan emerging).

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 Epsom and Ewell

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 Epsom and Ewell are listed below, taken from our Epsom and Ewell area page. Each one is a reason to confirm the address on Epsom and Ewell's constraints map before relying on permitted development.

Green Belt. A large share of the borough is Green Belt, including Epsom Common, Epsom Downs, the Hogsmill open space and land around Horton and Langley Vale. Source
Conservation areas. Epsom town centre, Ewell Village, Stamford Green and Woodcote are among the borough's conservation areas. Source
Hogsmill River flood risk. The Hogsmill River rises at Ewell and runs through Ewell Village, West Ewell and on towards Kingston, and land alongside it and its tributaries sits in Flood Zones 2 and 3. Source
Article 4 directions. The council has used, or has consulted on using, Article 4 directions to remove particular permitted development rights, including for converting houses into small houses in multiple occupation and for works in some conservation areas. Source
Listed buildings. Ewell Village, Epsom town centre and the old hospital estate at Horton contain listed houses, cottages, churches and institutional buildings. Source

What Epsom and Ewell planning officers look for

On the 1930s semis that dominate Stoneleigh, West Ewell and Ewell they tend to look for two-storey side extensions set back from the front wall and below the main ridge, a gap kept to the side boundary so the pair does not read as a terrace, and rear extensions that pass the 45-degree test to the neighbour's nearest habitable window. In the Green Belt officers usually measure the extension against the original dwelling by floorspace or volume and treat outbuildings more strictly. Common refusal reasons are full-width box dormers, side extensions that create a terracing effect, and roof extensions on front slopes in conservation areas. The council offers a paid pre-application service.

Fees and timelines

Epsom and Ewell 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.
Epsom and Ewell Borough Council: planning: the council's own constraints map, validation checklist and pre-application service.

Do I need planning permission for a rear extension in Epsom and Ewell?