House extension cost
in Kew.
Kew — TW9 — between Chiswick and Richmond, anchored by Kew Gardens. Generous Edwardian and inter-war housing, with strong family-buyer demand and consistently high property values.
What makes extension work in Kew distinct.
Housing: Edwardian and inter-war terraces and semis, plus some Victorian housing closer to the gardens.
Planning: Kew Green and Kew Gardens conservation areas cover central Kew. Article 4 applies on key streets near the gardens.
Applications go to LB Richmond 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 — TW9 numbers.
All figures inclusive of design, planning, build, contingency and VAT. The Kew multiplier (1.05×) 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 Kew and beyond.
Send me the guide.
What Kew homeowners ask us.
How much does a house extension cost in Kew in 2026?
Typical 2026 Kew ranges (inc. design, planning, build, contingency & VAT): side-return extensions £95k–£168k; single-storey rear £116k–£221k; wraparound £179k–£336k; double-storey rear £189k–£399k; basement £263k–£788k. The Kew multiplier (1.05×) reflects local labour rates, scaffold logistics and finish expectations.
Do I need planning permission for an extension in Kew?
Kew Green and Kew Gardens conservation areas cover central Kew. Article 4 applies on key streets near the gardens. 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 LB Richmond upon Thames.
What extension type works best for Kew houses?
Edwardian and inter-war terraces and semis, plus some Victorian housing closer to the gardens. 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 Kew?
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. LB Richmond upon Thames processes planning applications in approximately 8–13 weeks depending on backlog.
What hidden costs catch Kew homeowners out on extensions?
In TW9 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 Kew extensions?
Yes — Kew is within our core London catchment. Our studio is at 20 Dawes Road in Fulham, 7.0km from Kew. We've delivered extensions across the TW9 postcode and our subcontractor network covers Richmond upon Thames. Free site visit, fixed-price quote, 10-year HomePro guarantee on the finished work.
Extension pricing for Kew’s neighbours.
Twenty minutes on site in Kew.
On us.
Nick Elias RIBA and Vladimir will visit your Kew 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 Kew extension using the same 2026 rate card we quote real clients with.
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