House extension cost
in Hammersmith.
Hammersmith sits immediately north of Fulham along the A4 corridor. The terraces north of King Street and the riverside streets around Hammersmith Mall hold some of west London's most consistent late-Victorian housing stock.
What makes extension work in Hammersmith distinct.
Housing: Tall Victorian and Edwardian three-storey terraces with steep slate roofs — high loft potential, often suiting full L-shape dormers.
Planning: Brackenbury Village and St Peter's Square conservation areas cover much of north Hammersmith; expect full planning rather than PD on most streets.
Applications go to LB Hammersmith & Fulham. We submit on your behalf and handle party wall awards, build-over agreements and conservation officer correspondence end-to-end.
The five extension types — W6 numbers.
All figures inclusive of design, planning, build, contingency and VAT. The Hammersmith multiplier (1.02×) 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 Hammersmith and beyond.
Send me the guide.
What Hammersmith homeowners ask us.
How much does a house extension cost in Hammersmith in 2026?
Typical 2026 Hammersmith ranges (inc. design, planning, build, contingency & VAT): side-return extensions £92k–£163k; single-storey rear £112k–£214k; wraparound £173k–£326k; double-storey rear £184k–£388k; basement £255k–£765k. The Hammersmith multiplier (1.02×) reflects local labour rates, scaffold logistics and finish expectations.
Do I need planning permission for an extension in Hammersmith?
Brackenbury Village and St Peter's Square conservation areas cover much of north Hammersmith; expect full planning rather than PD on most streets. 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 Hammersmith & Fulham.
What extension type works best for Hammersmith houses?
Tall Victorian and Edwardian three-storey terraces with steep slate roofs — high loft potential, often suiting full L-shape dormers. 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 Hammersmith?
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 Hammersmith & Fulham processes planning applications in approximately 8–13 weeks depending on backlog.
What hidden costs catch Hammersmith homeowners out on extensions?
In W6 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 Hammersmith extensions?
Yes — Hammersmith is within our core London catchment. Our studio is at 20 Dawes Road in Fulham, 1.5km from Hammersmith. We've delivered extensions across the W6 postcode and our subcontractor network covers Hammersmith & Fulham. Free site visit, fixed-price quote, 10-year HomePro guarantee on the finished work.
Extension pricing for Hammersmith’s neighbours.
Twenty minutes on site in Hammersmith.
On us.
Nick Elias RIBA and Vladimir will visit your Hammersmith 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 Hammersmith extension using the same 2026 rate card we quote real clients with.
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