TL;DR — Key Facts
- Build cost per sqm: £2,500 – £3,800 (inner London borough)
- Council planning fee: £548 (householder application, 2026)
- Typical projects: rear extension, side-return, two-storey, wraparound
- Conservation areas: 43 designated areas in Southwark
- Permitted Development: Restricted by Article 4 in some areas
Extension costs in Southwark
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House extension build costs in Southwark typically range from £2,500 to £3,800 per square metre, reflecting Southwark's position as an inner London borough. These figures cover the construction cost only and do not include professional fees, planning fees, or VAT.
Camberwell and Peckham terraces price on structure: the side-return opening and the steel that spans it. Bermondsey and Borough's Georgian stock prices on heritage detailing and, frequently, listed building consent. On a Dulwich Estate address there is a third driver again - the Estate's own design standards, which can specify materials and detailing beyond what the council would require.
Typical extension costs in Southwark (build only)
On top of the build cost, you will need architectural drawings. These fees are 30% below typical London architect rates.
What affects extension costs in Southwark
Southwark approves 93.8% of householder applications, second-highest in London (MHCLG planning statistics, retrieved 1 September 2026), which makes the consent side comparatively low-risk. The complication is that much of SE21 and SE22 lies under the Dulwich Estate's scheme of management - a private consent with its own design standards and its own timetable, which a planning permission does not discharge and which needs budgeting for separately.
Conservation areas
Southwark has 43 designated conservation areas, including Camberwell Grove, Bermondsey Street, Dulwich Village, Peckham Rye, Borough. If your property is in a conservation area, Permitted Development rights are restricted, meaning you may need a full planning application (£548 council fee). Conservation area applications also tend to require higher-quality materials and more sympathetic design, which can increase build costs by 10-20%.
Article 4 Directions
Southwark has Article 4 Directions in place. Article 4 for HMOs borough-wide; additional Article 4 for office-to-residential in Bermondsey and Elephant & Castle. Where Article 4 applies, works that would normally be Permitted Development require a full planning application. This adds £548 to the council fee and typically 2-3 months to the project timeline, which can affect overall costs if you are renting alternative accommodation during the build.
Property type
The housing stock in Southwark is predominantly georgian and regency in bermondsey and borough; victorian terraces in camberwell and peckham; dulwich estate controlled housing; riverside new-build. Victorian and Edwardian terraces typically suit side-return and rear extensions, while 1930s semi-detached properties are well suited to two-storey rear extensions. Detached houses offer the most flexibility but often have larger footprints, meaning higher absolute costs even if the per-sqm rate is similar.
Access and logistics
Camberwell and Peckham are Victorian terrace where the rear is reached through the house. Bermondsey and Borough's Georgian and Regency stock sits on narrow streets with severe delivery constraints. On the Dulwich Estate the plots are generally larger with better access, and there the programme rather than the logistics is the variable, because two consents run in sequence.
Our drawing fees for Southwark extensions
At Architectural Drawings London. No hourly billing, no surprises. Our fees cover everything needed for a valid planning submission to Southwark Council and for building regulations approval.
Drawing fees for extensions in Southwark
Every package includes a measured survey of your existing property, existing floor plans and elevations, proposed floor plans and elevations, a site plan, and a design and access statement where required. Our MCIAT chartered architectural technologists handle the full process from survey to submission, and we liaise with Southwark Council on your behalf.
We cover all Southwark postcodes: SE1, SE5, SE15, SE16, SE17, SE21, SE22.
Planning vs Permitted Development in Southwark
Many house extensions in Southwark can be built under Permitted Development (PD) rights without needing a planning application. Under PD, single-storey rear extensions can extend up to 6 metres from the original rear wall for terraced and semi-detached houses, or 8 metres for detached houses (under the Prior Approval process). However, Southwark has Article 4 Directions that may remove some PD rights. Article 4 for HMOs borough-wide; additional Article 4 for office-to-residential in Bermondsey and Elephant & Castle.
Southwark's 43 conservation areas are backed by a Direction under Article 4 as well. On the Camberwell and Peckham terraces the side-extension prohibition has nothing to act on and materials govern. The complication here sits outside planning entirely: much of SE21 and SE22 falls under the Dulwich Estate's scheme of management, whose own standards apply whatever the council decides.
Two-storey extensions need an application, and Southwark grants them more readily than most: approval on householder work ran at 93.8% across the window, second-highest in the capital (MHCLG planning statistics, retrieved 1 September 2026). The complication is not the council. On a Dulwich Estate address in SE21 or SE22 the Estate's scheme of management applies in parallel, with its own design standards, and a planning permission does not satisfy it.
The council issued 604 certificates of lawful development in three years (MHCLG planning statistics, retrieved 1 September 2026). The figure is held down by the Article 4 Direction and 43 conservation areas. On a Dulwich Estate property a certificate is worth even less on its own than the count suggests, because it addresses only the planning position and says nothing about the Estate's consent, which is the one that will actually stop the work.
Frequently asked questions
How much does a house extension cost in Southwark?
Build costs for a house extension in Southwark typically range from £2,500 to £3,800 per square metre, as Southwark is an inner London borough. A typical single-storey rear extension of 15-20 sqm would cost between £37,500 and £76,000 for the build alone. On top of build costs.
Can I extend under Permitted Development in Southwark?
Southwark's 43 conservation areas carry the standard restrictions, and an Article 4 Direction removes more. The complication specific to this borough sits outside the planning system entirely: much of SE21 and SE22 falls under the Dulwich Estate's scheme of management, whose design standards apply in parallel and are not discharged by any planning permission the council grants.
How long does a house extension take in Southwark?
A typical house extension project in Southwark takes 5-8 months from initial instruction to completion. This breaks down as: 2-3 weeks for measured survey and drawing preparation, 8 weeks for planning determination by Southwark Council (if required), 2-4 weeks for building regulations approval, and 8-16 weeks for construction depending on the size and complexity of the extension.
Do I need a Party Wall Agreement for an extension in Southwark?
Two adjoining owners on the terraced stock. Southwark also served 16 temporary stop notices in three years (MHCLG planning statistics, retrieved 1 September 2026), among the highest counts in London, which is a specific reason not to begin excavation before the award is in place. On an Estate address you are sequencing three permissions - the Estate's, the council's, and the award - and the order matters.
What experience do you have with extensions in Southwark?
We prepare extension drawings for properties across all Southwark postcodes (SE1, SE5, SE15, SE16, SE17, SE21, SE22). Our MCIAT chartered architectural technologists understand Southwark Council's policies, design guides, and local precedents. We have a council-ready drawing review across all 33 London boroughs.
