House extension cost
in Marylebone.
Marylebone — W1 — north of Oxford Street. Georgian and early Victorian terraces, the Portman and Howard de Walden estates, and a strong concentration of mansion blocks.
What makes extension work in Marylebone distinct.
Housing: Georgian and Victorian terraces (estate-owned in many cases), plus large mansion blocks along Marylebone Road and Baker Street.
Planning: Marylebone Conservation Area covers the bulk of W1 north of Oxford Street. Many properties are listed or estate-managed with their own design covenants.
Applications go to City of 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 — W1 numbers.
All figures inclusive of design, planning, build, contingency and VAT. The Marylebone multiplier (1.20×) 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 Marylebone and beyond.
Send me the guide.
What Marylebone homeowners ask us.
How much does a house extension cost in Marylebone in 2026?
Typical 2026 Marylebone ranges (inc. design, planning, build, contingency & VAT): side-return extensions £108k–£192k; single-storey rear £132k–£252k; wraparound £204k–£384k; double-storey rear £216k–£456k; basement £300k–£900k. The Marylebone multiplier (1.20×) reflects local labour rates, scaffold logistics and finish expectations.
Do I need planning permission for an extension in Marylebone?
Marylebone Conservation Area covers the bulk of W1 north of Oxford Street. Many properties are listed or estate-managed with their own design covenants. 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 City of Westminster.
What extension type works best for Marylebone houses?
Georgian and Victorian terraces (estate-owned in many cases), plus large mansion blocks along Marylebone Road and Baker Street. 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 Marylebone?
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. City of Westminster processes planning applications in approximately 8–13 weeks depending on backlog.
What hidden costs catch Marylebone homeowners out on extensions?
In W1 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 Marylebone extensions?
Yes — Marylebone is within our core London catchment. Our studio is at 20 Dawes Road in Fulham, 6.0km from Marylebone. We've delivered extensions across the W1 postcode and our subcontractor network covers Westminster. Free site visit, fixed-price quote, 10-year HomePro guarantee on the finished work.
Extension pricing for Marylebone’s neighbours.
Twenty minutes on site in Marylebone.
On us.
Nick Elias RIBA and Vladimir will visit your Marylebone 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 Marylebone extension using the same 2026 rate card we quote real clients with.
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