House extension cost
in Kingston upon Thames.
Kingston upon Thames — KT1 — the historic riverside borough at the southern end of London. A mix of Victorian and Edwardian terraces in the town centre and generous inter-war housing on the slopes.
What makes extension work in Kingston upon Thames distinct.
Housing: Victorian and Edwardian terraces, Georgian houses around the market square, and 1920s/30s housing on the southern fringes.
Planning: Kingston Old Town, Liverpool Road and Coombe Hill conservation areas cover specific pockets.
Applications go to Royal Borough of Kingston upon Thames. We submit on your behalf and handle party wall awards, build-over agreements and conservation officer correspondence end-to-end.
The five extension types — KT1 numbers.
All figures inclusive of design, planning, build, contingency and VAT. The Kingston upon Thames multiplier (0.92×) 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 Kingston upon Thames and beyond.
Send me the guide.
What Kingston upon Thames homeowners ask us.
How much does a house extension cost in Kingston upon Thames in 2026?
Typical 2026 Kingston upon Thames ranges (inc. design, planning, build, contingency & VAT): side-return extensions £83k–£147k; single-storey rear £101k–£193k; wraparound £156k–£294k; double-storey rear £166k–£350k; basement £230k–£690k. The Kingston upon Thames multiplier (0.92×) reflects local labour rates, scaffold logistics and finish expectations.
Do I need planning permission for an extension in Kingston upon Thames?
Kingston Old Town, Liverpool Road and Coombe Hill conservation areas cover specific pockets. 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 Kingston upon Thames.
What extension type works best for Kingston upon Thames houses?
Victorian and Edwardian terraces, Georgian houses around the market square, and 1920s/30s housing on the southern fringes. 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 Kingston upon Thames?
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 Kingston upon Thames processes planning applications in approximately 8–13 weeks depending on backlog.
What hidden costs catch Kingston upon Thames homeowners out on extensions?
In KT1 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 Kingston upon Thames extensions?
Yes — Kingston upon Thames is within our core London catchment. Our studio is at 20 Dawes Road in Fulham, 11.0km from Kingston upon Thames. We've delivered extensions across the KT1 postcode and our subcontractor network covers Kingston upon Thames. Free site visit, fixed-price quote, 10-year HomePro guarantee on the finished work.
Extension pricing for Kingston upon Thames’s neighbours.
Twenty minutes on site in Kingston upon Thames.
On us.
Nick Elias RIBA and Vladimir will visit your Kingston upon Thames 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 Kingston upon Thames extension using the same 2026 rate card we quote real clients with.
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