The permitted development rules for side extensions
A single-storey side extension is permitted development on a house if it is no wider than half the width of the original house, no higher than 4 m, with eaves no higher than 3 m where it comes within 2 m of a boundary, and finished in materials similar in appearance to the house.
Anything wider than half the original house, any two-storey side extension, and any side extension on a flat needs planning permission. Garage conversions that keep the walls are usually permitted development; extending beyond them is assessed as a side extension.
What changes in Epping Forest
Side extensions are not permitted development in a conservation area at all, so there a planning application is always required.
The local constraints that most often decide the route in Epping Forest are listed below, taken from our Epping Forest area page. Each one is a reason to confirm the address on Epping Forest's constraints map before relying on permitted development.
- Epping Forest Special Area of Conservation. Epping Forest is a Special Area of Conservation, and the council requires new homes within its zone of influence to mitigate air-quality and recreational-pressure effects, usually through a financial contribution and a habitats assessment. Householder extensions and outbuildings to an existing house are, as we understand it, largely unaffected because they add no new dwelling, but any conversion that creates a new home needs the mitigation, and houses backing onto the Forest can face additional requirements. Check with the council early. Source
- Green Belt. Most of the district outside the built-up areas of Loughton, Buckhurst Hill, Epping, Waltham Abbey and Ongar is Metropolitan Green Belt, and it also washes over Chigwell Row, Theydon Bois and many villages. Extensions to houses in the Green Belt must not be disproportionate to the original dwelling, and outbuildings face a stricter test on size and siting. Check the council's constraints map for the boundary at your address. Source
- Conservation areas. The district's conservation areas include Epping High Street, several in Loughton and Buckhurst Hill, Chigwell village and Waltham Abbey town centre, along with many villages such as Theydon Bois, Ongar and Roydon. Roof extensions are not permitted development inside them, and officers apply the character appraisal to extensions and dormers. Check the constraints map for the exact boundaries before relying on permitted development. Source
- River Roding and River Lee flood risk. Land alongside the River Roding through Chigwell, Loughton, Abridge and Ongar, and alongside the River Lee and the Lee Navigation around Waltham Abbey and Roydon, sits in Flood Zones 2 and 3. Ground-floor extensions and basements there may need a flood risk statement with the application. Source
- Listed buildings. Epping High Street, Waltham Abbey, Chigwell village, Ongar and the rural parishes contain many listed houses, inns and churches, including the Abbey Church at Waltham Abbey. Listed building consent is needed for almost any alteration, internal or external. Source
What Epping Forest planning officers look for
Epping Forest officers assess householder applications against the Local Plan 2011–2033 and the council's supplementary guidance on residential extensions. On the 1930s semis and detached houses of Loughton, Buckhurst Hill and Chigwell 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, rear extensions that pass the 45-degree test to the neighbour's nearest habitable window, and hipped roofs kept where a gable would unbalance the pair. In Chigwell, Theydon Bois and other Green Belt areas they check the extension against the original house, count previous extensions towards the total and resist large outbuildings. In the conservation areas they expect traditional materials and subordinate dormers on rear slopes only. Common refusal reasons are full-width box dormers, side extensions that create a terracing effect, and disproportionate Green Belt extensions. Outside conservation areas, hip-to-gable and rear-dormer lofts within 50 m³ on a semi are routinely lawful and we secure a Lawful Development Certificate as proof. Epping Forest offers a paid pre-application service. Decisions can run past the statutory 8 weeks; allow 8–12 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.
