Can You Build a Basement Here?

Kensington and Chelsea has the tightest basement policy in London. Two of its criteria stop a scheme outright and the rest shape it. Answer five questions and see which apply to your house, each finding attributed to the clause it comes from.

The questions

Is the house listed?

Search the National Heritage List for the terrace as well as your own number. Many houses here are covered by a group listing that names the range rather than each address.

Is there already a basement?

A vault or an original cellar may or may not count as a basement storey for these purposes. The planning history for the address will settle it.

Where would the new space go?

Are there mature trees on the plot?

Root protection areas frequently decide the shape of an excavation, and some trees carry preservation orders.

The scheme includes a swimming poolA small additional allowance on depth may be permitted for a pool. It is the only latitude the policy offers.

The findings

Answer the first three questions and the findings will appear here, each one attributed to the criterion of Policy CD11 it comes from.

The checker above needs JavaScript to return its findings. The criteria it tests are set out below, and we are glad to work through them with you. Do send us the details of your house.

What it tests

Two Criteria Stop a Scheme. The Rest Shape It.

Policy CD11 of the Local Plan adopted in July 2024, which replaced the widely quoted CL7.

CD11(F)No Excavation Beneath a Listed Building: Stated without exception and without a balancing exercise, and it expressly includes vaults. A basement under the garden, clear of the footprint, may still be possible.
CD11(C)No Second Basement Storey: Where a basement exists under an extant or implemented permission, or was built under permitted development before those rights were withdrawn in 2015, no further floor may go beneath it.
CD11(A)Half the Garden, in One Piece: A basement must not exceed fifty per cent of each garden or open part of the site, measured as gross external area, and the unaffected half must be left in a single continuous area.
CD11(B)One Storey, Around Three to Four Metres: A single storey means one that cannot later be subdivided. A small additional allowance may be permitted for a swimming pool.
CD11(J)One Metre of Soil Above a Garden Basement: Found on top of the structure and its waterproofing, so it sets the slab level before the internal height is settled.
CD11(D)No Harm to Trees of Townscape Value: Root protection areas frequently govern the shape of the excavation, and some trees carry preservation orders.
CD11(G)Light Wells That Do Not Harm the Street: Resisted to the front or side where they would seriously harm the locality, and particularly where they are not already an established feature of the streetscape.
Article 100Planning Permission, Without Exception: Permitted development rights for basements were withdrawn across the whole borough with effect from April 2016. Flats never held them at all.