House Extensions in South Hampstead, NW6
We design and build South Hampstead house extensions across Goldhurst Terrace, Compayne Gardens, Fairhazel Gardens - side-return, rear, wraparound and double-storey additions for red-brick Victorian and Edwardian mansion blocks and substantial villas where planning strategy, conservation detailing, Party Wall sequencing and structural engineering need handling properly.
South Hampstead is one of London's great mansion-flat quarters, so extending a house here is the exception rather than the rule — and it is the larger surviving houses that make it possible. Most projects across the area are flat refurbishments, but the bigger houses among the red-brick streets suit whole-house work and reconfiguration.
The conservation area gives the district its coherence. Much of South Hampstead lies within the South Hampstead Conservation Area, a remarkably coherent grid of late-Victorian and Edwardian red-brick streets between West End Lane, the Metropolitan line, Belsize Road and Abbey Road, with mature trees and roofscape details that need careful treatment.
Camden applies Article 4 controls and scrutinises external change to the uniform red-brick frontages, so terracotta detailing is repaired sympathetically and sash windows restored. On the Camden guide a single-storey rear extension comes to £71,250–£112,500 excluding VAT and a side return to £90,000–£120,000 excluding VAT.
House Extensions in South Hampstead: Applied to the Local Stock
South Hampstead sits in the London Borough of Camden, and much of it lies within the South Hampstead Conservation Area — a remarkably coherent grid of late-Victorian and Edwardian red-brick streets. Camden’s South Hampstead Conservation Area appraisal is used for planning assessment. London-wide cost band for side return extension: £90,000–£120,000 excluding VAT (Resi side return cost guide, Feb 2026).
Sources: South Hampstead Conservation Area character appraisal and management strategy (adopted February 2011), Camden Council (2026); South Hampstead Conservation Area appraisal and management strategy page, Camden Council (2026); Side return extension (Resi side return cost guide, Feb 2026) (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 South Hampstead: Questions
Is South Hampstead in a conservation area?
Much of it. It lies within the South Hampstead Conservation Area, a remarkably coherent grid of late-Victorian and Edwardian red-brick streets between West End Lane, the Metropolitan line, Belsize Road and Abbey Road, with mature trees and roofscape details protected.
Which South Hampstead houses suit an extension?
The larger surviving houses. Most projects here are flat refurbishments, but the bigger houses among the 'Gardens' streets suit whole-house work and reconfiguration, which is where extension work tends to concentrate.
What does a house extension cost in South Hampstead?
Camden rear extensions run £71,250–£112,500 excluding VAT for a single storey; a side return is £90,000–£120,000 excluding VAT; and a wraparound an indicative market band of £100,000–£200,000.
How does Camden protect South Hampstead's frontages?
It applies Article 4 controls and scrutinises external change to the uniform red-brick frontages, so the terracotta detailing is repaired sympathetically and the sash windows restored, leaving a modern interior behind an unchanged period elevation.
Which South Hampstead streets do you work on?
Goldhurst Terrace, Compayne Gardens, Fairhazel Gardens and Canfield Gardens — block after block of tall red-brick mansion buildings interspersed with substantial villas and houses now in flats.
Can I extend my South Hampstead house?
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