Which Southwark postcodes does this basement extension service cover?
Every Southwark postcode district we draw in, the stock that dominates
it and the authority that validates a basement extension there. Southwark fees below are the
statutory England rates for 2026, not basement extension estimates.
| Postcode | Area | Dominant stock | What it means for a basement extension |
|---|
| SE1 | Bermondsey / Borough / Waterloo | Georgian terraces, post-war flats, new-build | A basement extension in Bermondsey / Borough / Waterloo may land with Southwark Council or Lambeth Council — SE1 crosses the boundary, and the SE1 policies map decides it street by street. |
| SE5 | Camberwell | Georgian villas, Victorian terraces | Camberwell is split at SE5. Either Southwark Council or Lambeth Council can determine a basement extension here, so the SE5 address is checked against both policies maps first. |
| SE15 | Peckham / Nunhead | Victorian terraces, post-war estates | A basement extension at an SE15 address in Peckham / Nunhead is determined by Southwark Council under its own Local Plan policies for Peckham / Nunhead. |
| SE16 | Bermondsey / Rotherhithe | Warehouse conversions, Georgian terraces, new-build | SE16 covers Bermondsey / Rotherhithe only; Southwark Council handles the basement extension. |
| SE17 | Walworth | Post-war estates, new-build towers | A basement extension at an SE17 address in Walworth is determined by Southwark Council under its own Local Plan policies for Walworth. |
| SE21 | Dulwich Village | Georgian villas, Edwardian villas (Dulwich Estate) | Dulwich Village is split at SE21. Either Southwark Council or Lambeth Council can determine a basement extension here, so the SE21 address is checked against both policies maps first. |
| SE22 | East Dulwich | Victorian and Edwardian terraces | A basement extension at an SE22 address in East Dulwich is determined by Southwark Council under its own Local Plan policies for East Dulwich. |
| SE24 | Herne Hill | Victorian villas, Edwardian terraces | Herne Hill is split at SE24. Either Lambeth Council or Southwark Council can determine a basement extension here, so the SE24 address is checked against both policies maps first. |
Which Southwark neighbourhoods suit a basement extension best?
Roof pitch, wall build-up and plot depth change every few Southwark
streets, and each one changes what a basement extension can achieve at that address.
- Borough (SE1) — Georgian and Victorian terraces, market quarter defines Borough, where georgian and victorian terraces, warehouse conversions set what a basement extension can do. Georgian houses here already have a vault and a lower-ground floor across SE1. Any Borough basement extension is validated by Southwark Council, with Borough Market the usual Borough reference point on the site plan.
- Camberwell (SE5) — a basement extension in Camberwell starts from georgian villas, victorian terraces, and Camberwell reads as Georgian villas, Victorian terraces. Georgian houses here already have a vault and a lower-ground floor in SE5. Southwark Council assesses Camberwell basement extensions against its own Camberwell character guidance, and the location plan we draw for Camberwell references Camberwell Green.
- Peckham (SE15) — a basement extension in Peckham starts from victorian terraces, post-war estates, and Peckham reads as Victorian terraces, creative renewal. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged in SE15. Southwark Council assesses Peckham basement extensions against its own Peckham character guidance, and the location plan we draw for Peckham references Peckham Rye.
- Dulwich Village (SE21) — basement extension work in Dulwich Village means georgian villas, edwardian villas (dulwich estate). Dulwich Village is Georgian and Edwardian villas, Estate-managed. Georgian houses here already have a vault and a lower-ground floor throughout SE21. Southwark Council decides the Dulwich Village application, and Dulwich Picture Gallery anchors the Dulwich Village location plan.
- East Dulwich (SE22) — basement extension work in East Dulwich means victorian and edwardian terraces. East Dulwich is Victorian and Edwardian terraces. Victorian cellars here convert without planning permission when the footprint and external appearance are unchanged throughout SE22. Southwark Council decides the East Dulwich application, and Lordship Lane anchors the East Dulwich location plan.
- Rotherhithe (SE16) — warehouse conversions, riverside defines Rotherhithe, where warehouse conversions, post-war estates, new-build set what a basement extension can do. Post-war slab foundations make basements here expensive and rarely viable across SE16. Any Rotherhithe basement extension is validated by Southwark Council, with Surrey Quays the usual Rotherhithe reference point on the site plan.
- Elephant and Castle (SE1, SE17) — basement extension work in Elephant and Castle means post-war estates, new-build towers. Elephant and Castle is regenerated quarter, modernist origins. Post-war slab foundations make basements here expensive and rarely viable throughout SE1. Southwark Council decides the Elephant and Castle application, and Elephant and Castle station anchors the Elephant and Castle location plan.
How do conservation areas and Article 4 affect a basement extension in Southwark?
Southwark conservation designations: there are 43 across Southwark Council, Borough, Camberwell Grove, Bermondsey Street among them. Designation costs a Southwark 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. Bermondsey Street is the Southwark designation that most often changes a basement extension design.
What Article 4 removes near Southwark: Article 4 for HMOs borough-wide; additional Article 4 for office-to-residential in Bermondsey and Elephant & Castle. Before pricing a basement extension we check whether the SE1 address is inside the mapped area, because Southwark Council draws the Southwark boundary street by street rather than across the whole of Southwark.
Southwark housing stock: Georgian and Regency in Bermondsey and Borough; Victorian terraces in Camberwell and Peckham; Dulwich Estate controlled housing; riverside new-build. Dulwich Estate private planning scheme affects much of SE21 and SE22; Southwark planning for rest of borough; strong heritage context. Read that before choosing a basement extension route in Southwark — construction, not postcode, sets what is achievable.
Which neighbouring authorities border Southwark?
- City of London — the City of London boundary runs against Southwark, so a basement extension a street from Southwark is decided by City of London Corporation instead. City of London runs 27 conservation areas across EC1 and its neighbours, which is why basement extensions priced for Southwark are re-checked against City of London policy whenever the Southwark address sits on that edge.
- Lambeth — adjoining Southwark, with 64 conservation areas centred on SE1. A basement extension on the far side of the Southwark line is determined by Lambeth Council, so the Southwark quote for basement extensions is checked against Lambeth guidance before it is issued.
- Lewisham — adjoining Southwark, with 30 conservation areas centred on SE3. A basement extension on the far side of the Southwark line is determined by Lewisham Council, so the Southwark quote for basement extensions is checked against Lewisham guidance before it is issued.
- Bromley — the Bromley boundary runs against Southwark, so a basement extension a street from Southwark is decided by Bromley Council instead. Bromley runs 48 conservation areas across BR1 and its neighbours, which is why basement extensions priced for Southwark are re-checked against Bromley policy whenever the Southwark address sits on that edge.
Sources for this Southwark 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.
