House extension cost
in Belgravia.
Belgravia — SW1 — between Knightsbridge and Pimlico. One of London's most architecturally homogeneous neighbourhoods, with stucco-fronted Italianate terraces laid out by Thomas Cubitt in the 1820s and 30s.
What makes extension work in Belgravia distinct.
Housing: Cubitt-era stucco terraces, four to six storeys, plus mews properties behind. A very high proportion are listed.
Planning: Belgravia Conservation Area covers the entire neighbourhood. Listed-building consent is required on most properties. Westminster Council is particularly protective of the rooflines.
Applications go to City of Westminster. We submit on your behalf and handle party wall awards, build-over agreements and conservation officer correspondence end-to-end.
The five extension types — SW1 numbers.
All figures inclusive of design, planning, build, contingency and VAT. The Belgravia multiplier (1.28×) 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 Belgravia and beyond.
Send me the guide.
What Belgravia homeowners ask us.
How much does a house extension cost in Belgravia in 2026?
Typical 2026 Belgravia ranges (inc. design, planning, build, contingency & VAT): side-return extensions £115k–£205k; single-storey rear £141k–£269k; wraparound £218k–£410k; double-storey rear £230k–£486k; basement £320k–£960k. The Belgravia multiplier (1.28×) reflects local labour rates, scaffold logistics and finish expectations.
Do I need planning permission for an extension in Belgravia?
Belgravia Conservation Area covers the entire neighbourhood. Listed-building consent is required on most properties. Westminster Council is particularly protective of the rooflines. 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 City of Westminster.
What extension type works best for Belgravia houses?
Cubitt-era stucco terraces, four to six storeys, plus mews properties behind. A very high proportion are listed. 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 Belgravia?
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. City of Westminster processes planning applications in approximately 8–13 weeks depending on backlog.
What hidden costs catch Belgravia homeowners out on extensions?
In SW1 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 Belgravia extensions?
Yes — Belgravia is within our core London catchment. Our studio is at 20 Dawes Road in Fulham, 5.0km from Belgravia. We've delivered extensions across the SW1 postcode and our subcontractor network covers Westminster. Free site visit, fixed-price quote, 10-year HomePro guarantee on the finished work.
Extension pricing for Belgravia’s neighbours.
Twenty minutes on site in Belgravia.
On us.
Nick Elias RIBA and Vladimir will visit your Belgravia 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.
One number. Sixty seconds. No callback.
Price your Belgravia extension using the same 2026 rate card we quote real clients with.
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