Maximum extension sizes without planning permission — applied to Brighton & Hove City Council in the South East. With moderate Gateway 2 fire-safety scrutiny and an average build cost of £2500/sqm, the deal arithmetic for permitted Development Extensions here is distinct from neighbouring boroughs.
Heads up: Brighton & Hove City Council operates Article 4 directions, so permitted Development Extensions that would normally be permitted development will likely require a full planning application here. Build that into your timeline and risk model.
Run any South East listing through Scapely to get a property-specific build cost, council objection-risk score and the AI Objection Risk Analyzer overlay applied to Brighton & Hove City Council's policy environment.
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