House
extensions
in Soho, W1
Architects, Engineers, Surveyors & Builders Under One Roof.
One Studio. One Contract. One Team.
RICS surveying support for party walls, licence to alter, conservation-area works & neighbour mattersWe design and build Soho house extensions across Dean Street, Greek Street, Frith Street - side-return, rear, wraparound and double-storey additions for Georgian townhouses, Soho converted houses and larger family homes where planning strategy, conservation detailing, Party Wall sequencing and structural engineering need handling properly.
House Extensions in Soho: What You Need to Know
Every house extension project in Soho is designed to respect the Soho Conservation Area and the character of Georgian townhouses, Soho conversions, mansion flats above retail. Our in-house RIBA Chartered Architects handle Westminster planning applications, our chartered structural engineers specify any load-bearing work, and our directly-employed trades deliver the build under one fixed-price contract. We coordinate Building Control, Party Wall awards where needed, and all certifications through to handover.
In Soho's conservation area, extensions must be designed with exceptional sensitivity. Westminster officers assess impact on the host building, neighbouring properties, and the wider streetscape. We secure planning approval through design excellence and thorough pre-application engagement.
Creative quarter with residential properties above ground-floor commercial premises. Tight urban grain with Georgian townhouses on quieter streets. Westminster conservation area. Our extensions in Soho use materials and detailing that complement the existing architecture — whether matching traditional brickwork and stonework or introducing high-quality contemporary glazing and zinc cladding.
Soho's residential life sits above its streets, and that intensely mixed grain drives the work. The area is in the City of Westminster, inside the Soho Conservation Area, on one of the densest and most historic street grids in London. Westminster's Soho guide records many listed 17th and 18th century buildings, listed Victorian theatres, protected squares and an archaeological-priority area around Gerrard Street and Cambridge Circus, so listed fabric and heritage justification frame nearly every project.
The logistics are exacting. Cost is driven by W1 restricted loading, the evening economy and theatre servicing, archaeology where the Lundenwic and Thorney Island area applies, party walls between narrow plots, waterproofing, flood and drainage evidence, lightwell design, and listed fabric. Dean Street, Frith Street and Greek Street keep fine Georgian townhouses, many now characterful flats and maisonettes, while Wardour Street adds upper-floor conversions over shops, bars and studios.
So a Soho scheme is planned around consents and access first, and priced accordingly. A rear extension is costed at about £71,250 to £112,500 before VAT, a side return near £90,000 to £120,000, with restricted loading adding to both.
House Extensions in Soho: Applied to the Local Stock
Soho sits in the City of Westminster, within the Soho Conservation Area, on one of the densest and most historic street grids in London. Westminster lists Soho conservation-area maps, a mini guide and an adopted audit. The council's Soho guide records many listed 17th and 18th century buildings, listed Victorian theatres, protected squares and an archaeological-priority area around Gerrard Street and Cambridge Circus; the Soho Neighbourhood Plan also forms part of the Westminster development-plan context.
Sources: Westminster City Council — Soho Conservation Area mini guide (May 2004) (2026); Westminster City Council — Conservation area audits, maps and guidance, L to Z (2026)
What a House Extension Involves
An extension reshapes how the whole ground floor works, not just how big it is — the new structure, the opening into the existing house, the kitchen and the garden connection all have to be designed as one move. We take each project from feasibility drawings through consents, structure and fit-out under a single fixed-price contract. Most extensions we build include the scope below.
- Rear extensions — single-storey additions that open the back of the house to the garden
- Side-return & wraparound — infilling the side alley of a terrace, alone or combined with a rear addition
- Double-storey — new bedrooms or bathrooms above the ground-floor addition, designed to sit comfortably with the original roofline
- Foundations & steel — groundworks, beams and the opening into the existing house, engineered by our own structural team
- Glazing — rooflights, glazed roofs and slim-framed sliding or bi-fold doors specified for light and thermal performance
- Kitchen integration — the kitchen layout planned with the architecture from the first drawing, not squeezed in afterwards
- Services & heating — electrics, plumbing, drainage and underfloor heating built into the new floor
- External works — patio, drainage connections and garden reinstatement completed within the contract
How We Run Your Project
Six stages, with the consents and engineering settled before the first spade goes in.
- Feasibility visit — we assess the site, the boundaries and your brief, and identify the right consent route for your property.
- Design & approvals — our architects draw the scheme while planning or permitted development paperwork, structural calculations and party wall notices progress together.
- Fixed-price contract — every element specified and priced before construction, from foundations to door hardware.
- Groundworks & shell — excavation, foundations, walls, steel and roof, taken to weathertight while you carry on living in the house.
- Fit-out — insulation, services, glazing, kitchen, flooring and decoration, with the opening into the existing house formed once the shell is sealed.
- Completion — building control inspection, snagging, external works and handover with the full certification pack.
Read the full house extension guide for extension types, permitted development limits and the build programme stage by stage.
Many rear extensions can proceed under permitted development — broadly up to 3m deep on attached houses and 4m on detached, extendable to 6m and 8m through the prior approval scheme — but conservation areas, Article 4 directions and listed status change the picture, and every extension needs Building Regulations approval regardless of the planning route. Where foundations come within 3m of a neighbouring building, the Party Wall etc. Act 1996 obliges you to give adjoining owners a minimum of two months’ written notice before construction can begin. Our planning guide library sets out the rules for each borough.
Why Hampstead Renovations
We hold £10 million public liability insurance with Aviva; the certificate is available on request.
House Extensions in Soho: Questions
Why is extending in Soho as much about consents and logistics as construction?
Because of the setting. Soho's surviving Georgian townhouses, characterful conversions and upper-floor flats — many listed, above a famously busy mixed-use ground floor — make work here as much about consents and logistics as construction. Westminster examines external change closely, and access on the tight streets is demanding.
How much of Soho is listed or protected?
A great deal. Westminster's Soho guide records many listed 17th and 18th century buildings, listed Victorian theatres, protected squares and an archaeological-priority area around Gerrard Street and Cambridge Circus. Soho sits within the Soho Conservation Area, on one of the densest and most historic street grids in London.
What does an extension cost in Soho?
London-wide guidance costs a Soho rear extension at about £71,250 to £112,500 before VAT. A side return is higher, near £90,000 to £120,000, with a wraparound at an indicative £100,000 to £200,000. In W1 the restricted loading, listed fabric and mixed-use neighbours usually push a scheme above what the plan area alone implies.
What construction constraints are specific to Soho?
Cost is driven by W1 logistics, restricted loading, the evening economy and theatre servicing, archaeology where the Lundenwic and Thorney Island area applies, party walls between narrow plots, waterproofing, flood and drainage evidence, lightwell design, and listed or conservation fabric. That intensely mixed grain drives every Soho project.
What kind of buildings will I be working on in Soho?
W1 here holds small-scale 17th and 18th century houses around Soho Square, Golden Square, Gerrard Street, Old Compton Street, Dean Street and Meard Street, alongside larger Victorian theatre, retail and media buildings on Shaftesbury Avenue and Wardour Street. Dean Street, Frith Street and Greek Street keep fine Georgian townhouses, many now characterful flats and maisonettes.
Book a Free Consultation
Visit our studio or invite us to survey your home. We’ll assess scope, discuss design possibilities and provide an honest budget framework — completely free.
Free Consultation
We survey your property, discuss your vision and provide a clear budget framework.