Which postcode districts around Kensington and Chelsea do we cover for basement extension work?
Every Kensington and Chelsea postcode district we draw in, the stock that dominates
it and the authority that validates a basement extension there. Kensington and Chelsea fees below are the
statutory England rates for 2026, not basement extension estimates.
| Postcode | Area | Dominant stock | What it means for a basement extension |
|---|
| W8 | Kensington | Stucco terraces, listed buildings | A basement extension at an W8 address in Kensington is determined by RBKC Planning under its own Local Plan policies for Kensington. |
| W10 | North Kensington / Ladbroke Grove | Victorian terraces, post-war estates | A basement extension at an W10 address in North Kensington / Ladbroke Grove is determined by RBKC Planning under its own Local Plan policies for North Kensington / Ladbroke Grove. |
| W11 | Notting Hill / Holland Park | Victorian stucco terraces | W11 covers Notting Hill / Holland Park only; RBKC Planning handles the basement extension. |
| SW1X | Knightsbridge / Belgravia | Regency stucco terraces, listed buildings | SW1X straddles a boundary: Knightsbridge / Belgravia addresses fall to Westminster City Council or RBKC Planning, so confirm which authority validates the basement extension before submitting SW1X drawings. |
| W14 | West Kensington / Barons Court | Victorian and Edwardian villas | West Kensington / Barons Court is split at W14. Either Hammersmith & Fulham Council or RBKC Planning can determine a basement extension here, so the W14 address is checked against both policies maps first. |
| SW3 | Chelsea / Brompton | Georgian and Victorian terraces, listed buildings | Chelsea / Brompton sits wholly inside SW3, so RBKC Planning validates every basement extension submitted from an SW3 address. |
| SW5 | Earl's Court | Stucco terraces, Edwardian mansion blocks | Earl's Court sits wholly inside SW5, so RBKC Planning validates every basement extension submitted from an SW5 address. |
| SW7 | South Kensington / Knightsbridge | Stucco terraces, mansion blocks, listed buildings | SW7 straddles a boundary: South Kensington / Knightsbridge addresses fall to RBKC Planning or Westminster City Council, so confirm which authority validates the basement extension before submitting SW7 drawings. |
How does a basement extension differ street by street across Kensington and Chelsea?
Roof pitch, wall build-up and plot depth change every few Kensington and Chelsea
streets, and each one changes what a basement extension can achieve at that address.
- Earl's Court (SW5) — a basement extension in Earl's Court starts from stucco terraces, edwardian mansion blocks, and Earl's Court reads as Victorian stucco terraces, mansion blocks. Edwardian houses rarely have a usable cellar in SW5. RBKC Planning assesses Earl's Court basement extensions against its own Earl's Court character guidance, and the location plan we draw for Earl's Court references Earl's Court station.
- South Kensington (SW7) — basement extension work in South Kensington means stucco terraces, mansion blocks, listed buildings. South Kensington is Victorian and Edwardian stucco terraces. Mansion blocks sit on shared foundations throughout SW7. RBKC Planning decides the South Kensington application, and V&A anchors the South Kensington location plan.
- Knightsbridge (SW1X, SW7) — a basement extension in Knightsbridge starts from regency and victorian terraces, mansion blocks, and Knightsbridge reads as Regency and Victorian terraces, luxury. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged in SW1X. RBKC Planning assesses Knightsbridge basement extensions against its own Knightsbridge character guidance, and the location plan we draw for Knightsbridge references Harrods.
- North Kensington (W10) — Victorian terraces, post-war estates defines North Kensington, where victorian terraces, post-war estates set what a basement extension can do. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged across W10. Any North Kensington basement extension is validated by RBKC Planning, with Golborne Road the usual North Kensington reference point on the site plan.
- Brompton (SW3) — Victorian stucco terraces, mansion blocks defines Brompton, where stucco terraces, edwardian mansion blocks set what a basement extension can do. Edwardian houses rarely have a usable cellar across SW3. Any Brompton basement extension is validated by RBKC Planning, with Brompton Cross the usual Brompton reference point on the site plan.
- Kensington (W8) — a basement extension in Kensington starts from stucco terraces, listed buildings, and Kensington reads as Georgian and Victorian stucco terraces. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged in W8. RBKC Planning assesses Kensington basement extensions against its own Kensington character guidance, and the location plan we draw for Kensington references Kensington Palace.
- Chelsea (SW3, SW10) — Georgian and Victorian terraces, riverside defines Chelsea, where georgian and victorian terraces, listed buildings set what a basement extension can do. Georgian houses here already have a vault and a lower-ground floor across SW3. Any Chelsea basement extension is validated by RBKC Planning, with King's Road the usual Chelsea reference point on the site plan.
What local planning policy applies to a basement extension in Kensington and Chelsea?
Kensington and Chelsea conservation designations: there are 38 across RBKC Planning, Chelsea, Notting Hill, Holland Park among them. Designation costs a Kensington and Chelsea owner the permitted-development route: a basement extension then needs a £548 householder application over 8 weeks, in place of the £249 prior approval route that takes 6 weeks. Earls Court is the Kensington and Chelsea designation that most often changes a basement extension design.
What Article 4 removes near Kensington and Chelsea: Article 4 Directions covering HMOs, office-to-residential, and basement developments — RBKC has some of the strictest basement policies in London. Before pricing a basement extension we check whether the SW3 address is inside the mapped area, because RBKC Planning draws the Kensington and Chelsea boundary street by street rather than across the whole of Kensington and Chelsea.
Kensington and Chelsea below-ground policy: RBKC's basement policy (post-2015) limits to single-storey under 50% of garden area; double-storey basements effectively prohibited in residential streets. Any basement extension in Kensington and Chelsea that goes below existing foundations triggers two months notice under section 6 of the Party Wall etc. Act 1996, and RBKC Planning will want the SW3 ground and groundwater position set out.
The building fabric around Kensington and Chelsea: Grand white stucco Regency and Victorian terraces; red-brick Queen Anne mansions in Kensington; Edwardian mansion blocks; almost no post-war housing stock. Internationally wealthy residents; extensive listed building coverage; heritage and streetscape prioritised in every decision. A basement extension in Kensington and Chelsea is scoped against that stock first.
Who decides a basement extension on the edge of Kensington and Chelsea?
- Westminster — the Westminster boundary runs against Kensington and Chelsea, so a basement extension a street from Kensington and Chelsea is decided by Westminster City Council instead. Westminster runs 56 conservation areas across SW1 and its neighbours, which is why basement extensions priced for Kensington and Chelsea are re-checked against Westminster policy whenever the Kensington and Chelsea address sits on that edge.
- Hammersmith and Fulham — adjoining Kensington and Chelsea, with 45 conservation areas centred on W6. A basement extension on the far side of the Kensington and Chelsea line is determined by Hammersmith & Fulham Council, so the Kensington and Chelsea quote for basement extensions is checked against Hammersmith and Fulham guidance before it is issued.
- Brent — adjoining Kensington and Chelsea, with 22 conservation areas centred on NW2. A basement extension on the far side of the Kensington and Chelsea line is determined by Brent Council, so the Kensington and Chelsea quote for basement extensions is checked against Brent guidance before it is issued.
Sources for this Kensington and Chelsea basement extension page: borough policies maps and
conservation-area registers (2025–26), Royal Mail postcode district boundaries,
the Town and Country Planning (Fees for Applications) (England) Regulations, the Town
and Country Planning (General Permitted Development) (England) Order 2015 as amended,
and the Party Wall etc. Act 1996.
