House extension cost
in Knightsbridge.
Knightsbridge — straddling the SW1/SW7 boundary between RBKC and Westminster. The mansion blocks and grand terraces around Hyde Park represent some of the most valuable property in the world.
What makes extension work in Knightsbridge distinct.
Housing: Mansion blocks, large stucco terraces, mews behind. Single-family homes are the exception, not the rule.
Planning: Multiple conservation areas overlap; Knightsbridge Green and Albert Gate are particularly restrictive. Listed buildings are common.
Applications go to RBKC & 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 Knightsbridge 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 Knightsbridge and beyond.
Send me the guide.
What Knightsbridge homeowners ask us.
How much does a house extension cost in Knightsbridge in 2026?
Typical 2026 Knightsbridge 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 Knightsbridge multiplier (1.28×) reflects local labour rates, scaffold logistics and finish expectations.
Do I need planning permission for an extension in Knightsbridge?
Multiple conservation areas overlap; Knightsbridge Green and Albert Gate are particularly restrictive. Listed buildings are 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 RBKC & Westminster.
What extension type works best for Knightsbridge houses?
Mansion blocks, large stucco terraces, mews behind. Single-family homes are the exception, not the rule. 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 Knightsbridge?
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. RBKC & Westminster processes planning applications in approximately 8–13 weeks depending on backlog.
What hidden costs catch Knightsbridge 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 Knightsbridge extensions?
Yes — Knightsbridge is within our core London catchment. Our studio is at 20 Dawes Road in Fulham, 3.5km from Knightsbridge. We've delivered extensions across the SW1 postcode and our subcontractor network covers Kensington & Chelsea / Westminster. Free site visit, fixed-price quote, 10-year HomePro guarantee on the finished work.
Extension pricing for Knightsbridge’s neighbours.
Twenty minutes on site in Knightsbridge.
On us.
Nick Elias RIBA and Vladimir will visit your Knightsbridge 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 Knightsbridge extension using the same 2026 rate card we quote real clients with.
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