The First Thing to Understand
The dense urban fabric, limited rear garden sizes, and significant conservation area coverage across the BN1 area mean that building extensions here require particularly careful planning — rear extensions are often the only viable option, and many properties in the conservation areas require full planning permission even for modest single-storey additions.
The area is a city in East Sussex, South East England, administered by Brighton and Hove City Council. The postcode districts covering the area are BN1, BN2, BN3. Nearby areas include Hove, Worthing, Lewes, Shoreham-by-Sea. Single-storey rear extensions within permitted development limits do not require a planning application — your builder should confirm the PD position for your specific property before design work begins.
What to Expect from a Brighton Building Extension
Brighton and Hove City Council has extensive conservation area coverage across much of the city — including the Regency and Victorian areas close to the seafront and city centre where a large proportion of the housing sits. Even modest extensions in these protected areas require full planning applications, and the council's expectations for design quality are high.
Building Regulations and Planning in Brighton BN1
Brighton's building market is expensive — above the national average for contractor rates and material costs. A 20 square metre single-storey rear extension here typically costs £42,000–£64,000, and conservation area work with high design specification costs more. The city's strong property market makes extension investment worthwhile, but the planning process in protected areas takes time and expertise to navigate.