House extension cost
in Kensington.
Kensington — W8 — runs from Notting Hill to South Kensington. Some of the most expensive postcodes in London, with housing ranging from Georgian terraces around Kensington Square to Italianate Victorian villas.
What makes extension work in Kensington distinct.
Housing: Georgian and early Victorian terraces, large stucco villas, plus garden-square set-pieces like Kensington Square and Edwardes Square.
Planning: The entire W8 postcode falls within Kensington Conservation Area, with overlapping Edwardes Square, De Vere and Phillimore conservation areas. Many properties are listed.
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 — W8 numbers.
All figures inclusive of design, planning, build, contingency and VAT. The 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 Kensington and beyond.
Send me the guide.
What Kensington homeowners ask us.
How much does a house extension cost in Kensington in 2026?
Typical 2026 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 Kensington multiplier (1.25×) reflects local labour rates, scaffold logistics and finish expectations.
Do I need planning permission for an extension in Kensington?
The entire W8 postcode falls within Kensington Conservation Area, with overlapping Edwardes Square, De Vere and Phillimore conservation areas. Many properties are listed. 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 Kensington houses?
Georgian and early Victorian terraces, large stucco villas, plus garden-square set-pieces like Kensington Square and Edwardes Square. 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 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 Kensington homeowners out on extensions?
In W8 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 Kensington extensions?
Yes — Kensington is within our core London catchment. Our studio is at 20 Dawes Road in Fulham, 2.5km from Kensington. We've delivered extensions across the W8 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 Kensington’s neighbours.
Twenty minutes on site in Kensington.
On us.
Nick Elias RIBA and Vladimir will visit your 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.
One number. Sixty seconds. No callback.
Price your Kensington extension using the same 2026 rate card we quote real clients with.
Price my Kensington extension →