Side extensions in Broxbourne depend on the house. Typical homes here: 1930s semi-detached houses in Cheshunt, Flamstead End, Turnford, Hoddesdon and Rye Park; Post-war semi-detached and terraced houses in Cheshunt, Waltham Cross and Hoddesdon. Designations to check first: Green Belt; Lee Valley Regional Park and River Lea flood risk; Conservation areas. Applications are decided by Borough of Broxbourne and the Broxbourne Local Plan 2018–2033.
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 Broxbourne
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 Broxbourne are listed below, taken from our Broxbourne area page. Each one is a reason to confirm the address on Broxbourne's constraints map before relying on permitted development.
- Green Belt. Land west of the A10, including Goffs Oak and the countryside around Cheshunt and Hoddesdon, is Green Belt, along with much of the Lee Valley to the east. Source
- Lee Valley Regional Park and River Lea flood risk. The Lee Valley Regional Park runs the length of the borough east of the railway, and land alongside the River Lea, the Lee Navigation and the reservoirs sits in Flood Zones 2 and 3. Source
- Conservation areas. Broxbourne's conservation areas include Hoddesdon town centre, Broxbourne, Wormley and parts of Cheshunt, with others in the villages. Source
- Article 4 direction on HMOs. We understand the Borough of Broxbourne has used an Article 4 direction to remove permitted development for converting a house into a small house in multiple occupation (C3 to C4), so HMO conversions normally need planning permission. Source
- Listed buildings. Hoddesdon High Street, Broxbourne, Wormley and the older parts of Cheshunt and Waltham Cross contain listed houses, inns and churches, including the Eleanor Cross at Waltham Cross. Source
What Broxbourne planning officers look for
Broxbourne officers assess householder applications against the Broxbourne Local Plan 2018–2033 and the council's supplementary guidance on residential extensions. On the 1930s and post-war semis that dominate Cheshunt and Hoddesdon 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. 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.
Fees and timelines
Broxbourne 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.
- Borough of Broxbourne: planning: the council's own constraints map, validation checklist and pre-application service.
