Basement extensions in Brent: 98.9% never see committee

Where in Brent does a basement extension actually get determined?

Every Brent postcode district we draw in, the stock that dominates it and the authority that validates a basement extension there. Brent fees below are the statutory England rates for 2026, not basement extension estimates.

What changes about a basement extension in each part of Brent?

Roof pitch, wall build-up and plot depth change every few Brent streets, and each one changes what a basement extension can achieve at that address.

• Wembley (HA0, HA9) — basement extension work in Wembley means 1930s semi-detached, new-build. Wembley is 1930s semi-detached, major regen. 1930s houses were built without cellars throughout HA0. Brent Council decides the Wembley application, and Wembley Stadium anchors the Wembley location plan.
• Kilburn (NW6) — a basement extension in Kilburn starts from victorian terraces, mansion blocks, and Kilburn reads as Victorian terraces, mansion blocks. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged in NW6. Brent Council assesses Kilburn basement extensions against its own Kilburn character guidance, and the location plan we draw for Kilburn references Kilburn High Road.
• Queen's Park (NW6) — basement extension work in Queen's Park means edwardian villas. Queen's Park is Edwardian villas, conservation. Edwardian houses rarely have a usable cellar throughout NW6. Brent Council decides the Queen's Park application, and Queen's Park anchors the Queen's Park location plan.
• Harlesden (NW10) — a basement extension in Harlesden starts from victorian terraces, and Harlesden reads as Victorian terraces. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged in NW10. Brent Council assesses Harlesden basement extensions against its own Harlesden character guidance, and the location plan we draw for Harlesden references Harlesden High Street.
• Mapesbury (NW2) — a basement extension in Mapesbury starts from edwardian villas and terraces, and Mapesbury reads as Edwardian conservation area. Edwardian houses rarely have a usable cellar in NW2. Brent Council assesses Mapesbury basement extensions against its own Mapesbury character guidance, and the location plan we draw for Mapesbury references Mapesbury Conservation Area.
• Kensal Green (NW10) — basement extension work in Kensal Green means victorian terraces. Kensal Green is Victorian terraces. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged throughout NW10. Brent Council decides the Kensal Green application, and Kensal Green Cemetery anchors the Kensal Green location plan.
• Willesden (NW10) — basement extension work in Willesden means victorian terraces, edwardian terraces. Willesden is Victorian terraces, Edwardian. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged throughout NW10. Brent Council decides the Willesden application, and Willesden Green Tube anchors the Willesden location plan.

How do conservation areas and Article 4 affect a basement extension in Brent?

Conservation areas covering Brent: Brent Council runs 22, and Sudbury Court, Queen's Park, Mapesbury are the ones Brent owners meet most. A basement extension inside a Brent conservation area loses permitted development, so the Brent submission is a householder application at £548 decided in 8 weeks — not a £249 prior approval decided in 6 weeks. In Kensal Green a basement extension is judged on the street elevation first.

What Article 4 removes near Brent: Article 4 for HMO conversions in specific streets around Wembley and Harlesden. Before pricing a basement extension we check whether the NW2 address is inside the mapped area, because Brent Council draws the Brent boundary street by street rather than across the whole of Brent.

Brent housing stock: Edwardian villas in Queen's Park and Mapesbury; Victorian terraces in Kilburn and Harlesden; 1930s semi-detached in Wembley; post-war tower blocks in Church End. Highly diverse borough; Queen's Park and Mapesbury are heritage-controlled; Wembley is a major regeneration hub. Read that before choosing a basement extension route in Brent — construction, not postcode, sets what is achievable.

Who decides a basement extension on the edge of Brent?

• Hammersmith and Fulham — the Hammersmith and Fulham boundary runs against Brent, so a basement extension a street from Brent is decided by Hammersmith & Fulham Council instead. Hammersmith and Fulham runs 45 conservation areas across W6 and its neighbours, which is why basement extensions priced for Brent are re-checked against Hammersmith and Fulham policy whenever the Brent address sits on that edge.
• Ealing — cross the Brent boundary and Ealing Council takes the basement extension instead, applying 30 conservation areas of its own around W3. We re-price basement extensions at the Brent edge because Ealing policy and Brent policy rarely align on basement extension depth.
• Harrow — adjoining Brent, with 29 conservation areas centred on HA1. A basement extension on the far side of the Brent line is determined by Harrow Council, so the Brent quote for basement extensions is checked against Harrow guidance before it is issued.
• Barnet — the Barnet boundary runs against Brent, so a basement extension a street from Brent is decided by Barnet Council instead. Barnet runs 20 conservation areas across N2 and its neighbours, which is why basement extensions priced for Brent are re-checked against Barnet policy whenever the Brent address sits on that edge.

Sources for this Brent 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.