The Same Framework, a Different Stock
Chelsea sits in the Royal Borough of Kensington and Chelsea, so everything that governs a house in Holland Park governs one here: the Local Plan adopted in July 2024, Policy CD11 on basements, Policy CD4 on conservation areas, Policy CD5 on listed buildings, and the borough-wide Article 4 direction that removed permitted development rights for basement work in 2016.
What differs is the fabric the framework is applied to. The borough has thirty-eight conservation areas covering around seventy-three per cent of its land, and a dozen of them are in Chelsea: Chelsea itself, Cheyne, The Boltons, Royal Hospital, Hans Town, Sloane Square, Chelsea Park and Carlyle, Thames, Brompton, Sloane and Stanley, The Billings, and Lots Village.
Each has its own adopted appraisal and its own Article 4 directions, and they are no more interchangeable than Norland and Ladbroke are in the north. The right first question in Chelsea is the same as anywhere in the borough: which conservation area is the house in, and what has been withdrawn there.
What Carries Across from the North
The basement policy, in full. CD11 permits no more than one storey, generally taken as three to four metres floor to ceiling, and no more than fifty per cent of each garden or open part of the site, with the unaffected half left in a single continuous area. A minimum of one metre of soil is required above any part beneath a garden. Excavation beneath a listed building is forbidden outright, including beneath vaults.
The construction regime, in full. Basement excavation is a Category 1 site under the borough's Code of Construction Practice, which confines noisy works to eight until six on weekdays with nothing at all at weekends, restricts demolition and concrete breaking to two windows a day, limits deliveries to between half past nine and half past four, and requires a construction bond before work starts.
And the amalgamation policy. Policy HO1(B) protects existing homes and does not allow the combination of self-contained flats, with a narrow exception for two into one where the existing homes are genuinely substandard. The classic Chelsea project of returning a subdivided house to single occupation is, as a rule, refused.
What We Can and Cannot Tell You Yet
We have written the Holland Park, Notting Hill and Kensington conservation areas up in detail, area by area, from the borough's own adopted appraisals. The Chelsea areas are not yet written up to that standard, and we would rather say so than repeat generic copy about period property.
What we can do now is match a house here to practices that work in Chelsea regularly, and tell you which conservation area governs it and what the borough-wide policies mean for the scheme you have in mind. Tell us the address and we will come back with both.