House extension cost
in South Kensington.
South Kensington — SW7 — the museum quarter and one of the densest concentrations of Italianate Victorian terraces in London. The Onslow, Brompton and Cromwell grid is among RBKC's most architecturally protected.
What makes extension work in South Kensington distinct.
Housing: Tall Italianate stucco terraces, four to five storeys, mostly converted to large flats with some intact single-family homes.
Planning: Thurloe-Smith's Charity, Brompton, Queen's Gate and Cornwall conservation areas overlap across SW7. Listed-building consent is common.
Applications go to Royal Borough of Kensington & Chelsea. We submit on your behalf and handle party wall awards, build-over agreements and conservation officer correspondence end-to-end.
The five extension types — SW7 numbers.
All figures inclusive of design, planning, build, contingency and VAT. The South Kensington multiplier (1.25×) reflects local labour, scaffolding logistics, conservation requirements and finish expectations.
The 2026 London Extension Cost Guide.
Borough-by-borough pricing, a full £200k cost breakdown, PD vs full planning explained, and the seven hidden costs to watch for in South Kensington and beyond.
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What South Kensington homeowners ask us.
How much does a house extension cost in South Kensington in 2026?
Typical 2026 South Kensington ranges (inc. design, planning, build, contingency & VAT): side-return extensions £113k–£200k; single-storey rear £138k–£263k; wraparound £213k–£400k; double-storey rear £225k–£475k; basement £313k–£938k. The South Kensington multiplier (1.25×) reflects local labour rates, scaffold logistics and finish expectations.
Do I need planning permission for an extension in South Kensington?
Thurloe-Smith's Charity, Brompton, Queen's Gate and Cornwall conservation areas overlap across SW7. Listed-building consent is common. Outside conservation areas, single-storey rear extensions up to 3m (terrace/semi) or 4m (detached) usually qualify for permitted development. Side-returns, wraparounds, double-storey extensions and anything in a conservation area need full planning. Applications go to Royal Borough of Kensington & Chelsea.
What extension type works best for South Kensington houses?
Tall Italianate stucco terraces, four to five storeys, mostly converted to large flats with some intact single-family homes. On this housing stock, the most common 2VP extension is a single-storey rear or wraparound — adding 20–35 m² of open-plan kitchen-diner. Double-storey extensions become viable on properties with rear gardens deep enough to absorb the additional volume without overshadowing.
How long does an extension take in South Kensington?
Allow 8–12 weeks for design and planning (longer in conservation areas), then 16–22 weeks on site for a single-storey, 22–30 weeks for a wraparound or double-storey, and 28–40 weeks for a basement. Royal Borough of Kensington & Chelsea processes planning applications in approximately 8–13 weeks depending on backlog.
What hidden costs catch South Kensington homeowners out on extensions?
In SW7 the top items are: party wall awards (£1,000–£3,000 per neighbour — common on terraced streets), build-over agreements with Thames Water (£300–£1,500 where drains run beneath the proposed extension), conservation officer consultations, structural engineer fees, drainage and asbestos surveys, and VAT at 20% on top of the base build cost. All of these are itemised in our fixed-price quote.
Does 2VP work on South Kensington extensions?
Yes — South Kensington is within our core London catchment. Our studio is at 20 Dawes Road in Fulham, 3.0km from South Kensington. We've delivered extensions across the SW7 postcode and our subcontractor network covers Kensington & Chelsea. Free site visit, fixed-price quote, 10-year HomePro guarantee on the finished work.
Extension pricing for South Kensington’s neighbours.
Twenty minutes on site in South Kensington.
On us.
Nick Elias RIBA and Vladimir will visit your South Kensington home, walk the site, check planning constraints, advise on PD vs full planning, and give you a realistic budget and programme — even if an extension isn’t the right move.
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Price your South Kensington extension using the same 2026 rate card we quote real clients with.
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