Which Wandsworth postcodes does this basement extension service cover?
Every Wandsworth district we draw in, the housing standing in it, and which authority an application from there is decided by. Fees set out below are 2026 statutory England rates, payable to the council and quite separate from design costs.
| Postcode | Area | Dominant stock | What it means for a basement extension |
|---|
| SW11 | Battersea / Clapham Junction | Victorian terraces, mansion blocks | A basement extension at an SW11 address in Battersea / Clapham Junction is determined by Wandsworth Council under its own Local Plan policies for Battersea / Clapham Junction. |
| SW12 | Balham | Victorian and Edwardian terraces | Balham straddles the SW12 boundary between Wandsworth and Lambeth. Which of the two determines a basement scheme is settled by the address, not by the district. |
| SW15 | Putney / Roehampton | Edwardian terraces, Victorian villas, mansion blocks | SW15 is Putney and Roehampton, wholly Wandsworth, and its case officers work to the SW15 conservation-area boundaries. |
| SW17 | Tooting / Earlsfield | Edwardian terraces | SW17 takes in Tooting and Earlsfield and reaches into Merton, so confirm whether Wandsworth or Merton will be taking the application before drawings go out. |
| SW18 | Wandsworth / Earlsfield / Southfields | Victorian villas and terraces | SW18 covers Wandsworth / Earlsfield / Southfields only; Wandsworth Council handles the basement extension. |
| SW4 | Clapham | Victorian terraces, Edwardian villas | Clapham sits across the SW4 boundary, with either Lambeth or Wandsworth determining, so both policies maps are checked at the outset. |
| SW8 | South Lambeth / Nine Elms | Victorian terraces, new-build apartments | SW8 spans South Lambeth and Nine Elms and is split between Lambeth and Wandsworth; the address decides which of them determines a basement scheme. |
| SW16 | Streatham / Norbury | Edwardian terraces, post-war flats | SW16, around Streatham and Norbury, is divided between Lambeth, Wandsworth, Merton and Croydon. Four authorities inside one district, so it is the address that has to be checked, never the postcode. |
Which Wandsworth neighbourhoods suit a basement extension best?
Councillors decide very little here. Officers took 6,071 of the 6,306 Wandsworth applications determined across the twelve published quarters, 96.3% of them, against 97.0% for the capital as a whole. The 235 that did reach committee are the contentious ones, and a basement is precisely the sort of scheme that gets there. Source: MHCLG live planning statistics
- Nightingale Triangle (SW12) — Edwardian conservation area defines Nightingale Triangle, where edwardian terraces and villas set what a basement extension can do. Edwardian houses rarely have a usable cellar across SW12. Any Nightingale Triangle basement extension is validated by Wandsworth Council, with Nightingale Lane the usual Nightingale Triangle reference point on the site plan.
- Roehampton (SW15) — Modernist post-war estates, Georgian fragments defines Roehampton, where post-war estates, georgian villas set what a basement extension can do. Georgian houses here already have a vault and a lower-ground floor across SW15. Any Roehampton basement extension is validated by Wandsworth Council, with Alton Estate the usual Roehampton reference point on the site plan.
- Clapham Junction (SW11) — a basement extension in Clapham Junction starts from victorian terraces, mansion blocks, and Clapham Junction reads as Victorian terraces, transport hub. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged in SW11. Wandsworth Council assesses Clapham Junction basement extensions against its own Clapham Junction character guidance, and the location plan we draw for Clapham Junction references Clapham Junction station.
- Battersea (SW8, SW11) — Victorian terraces, riverside regen at Power Station defines Battersea, where victorian terraces, new-build apartments set what a basement extension can do. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged across SW8. Any Battersea basement extension is validated by Wandsworth Council, with Battersea Power Station the usual Battersea reference point on the site plan.
- Balham (SW12) — a basement extension in Balham starts from victorian and edwardian terraces, and Balham reads as Victorian and Edwardian terraces. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged in SW12. Wandsworth Council assesses Balham basement extensions against its own Balham character guidance, and the location plan we draw for Balham references Balham High Road.
- Tooting (SW17) — basement extension work in Tooting means edwardian terraces. Tooting is Edwardian terraces, vibrant high street. Edwardian houses rarely have a usable cellar throughout SW17. Wandsworth Council decides the Tooting application, and Tooting Market anchors the Tooting location plan.
- Wandsworth Common (SW17, SW18) — basement extension work in Wandsworth Common means victorian villas and terraces. Wandsworth Common is Victorian villas around the common. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged throughout SW17. Wandsworth Council decides the Wandsworth Common application, and Wandsworth Common anchors the Wandsworth Common location plan.
How do conservation areas and Article 4 affect a basement extension in Wandsworth?
How designation changes a Wandsworth basement extension: Wandsworth Council’s own list names 45 conservation areas, including Clapham Common West, Tonsley, Magdalen Park. Inside any of them a Wandsworth basement extension cannot rely on permitted development, and the route becomes a £548 householder application determined in 8 weeks rather than a £249 prior approval in 6 weeks. Tonsley sets the tone for Wandsworth casework.
Wandsworth and Article 4: Article 4 for HMO conversions covering the whole borough. A basement extension planned at a SW11 address is checked against that direction first; Wandsworth Council publishes the Wandsworth extent, and the SW11 line rarely follows the Wandsworth boundary you would expect.
What Wandsworth is built from: Extensive Victorian terraced streets — the classic London side-return extension opportunity; Edwardian villas around the commons; 1930s semi-detached in Southfields. Family-oriented, high side-return extension and loft conversion rates; planning department experienced with Victorian terrace modifications. That mix decides the basement extension route in Wandsworth more than the postcode does.
Who decides a basement extension on the edge of Wandsworth?
- Lambeth — adjoining Wandsworth, with 64 conservation areas centred on SE1. A basement extension on the far side of the Wandsworth line is determined by Lambeth Council, so the Wandsworth quote for basement extensions is checked against Lambeth guidance before it is issued.
- Merton — the Merton boundary runs against Wandsworth, so a basement extension a street from Wandsworth is decided by Merton Council instead. Merton runs 28 conservation areas across SW16 and its neighbours, which is why basement extensions priced for Wandsworth are re-checked against Merton policy whenever the Wandsworth address sits on that edge.
- Kingston upon Thames — the Kingston upon Thames boundary runs against Wandsworth, so a basement extension a street from Wandsworth is decided by Kingston Council instead. Kingston upon Thames runs 22 conservation areas across KT1 and its neighbours, which is why basement extensions priced for Wandsworth are re-checked against Kingston upon Thames policy whenever the Wandsworth address sits on that edge.
- Richmond upon Thames — cross the Wandsworth boundary and Richmond Council takes the basement extension instead, applying 72 conservation areas of its own around SW13. We re-price basement extensions at the Wandsworth edge because Richmond upon Thames policy and Wandsworth policy rarely align on basement extension depth.
Sources for this Wandsworth 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.
