For detailed information on process, pricing tiers, technical specifications, and FAQs, see our comprehensive house extensions guide.
View Full House Extensions Guide →Across South West London, the most successful extensions are the ones that solve how the house actually works: cramped kitchens, disconnected dining rooms, dark rear corners and circulation that no longer matches family life.
The technical work sits behind the beautiful glazing and joinery. In South West London, terrace-house extension rules, basement scrutiny, conservation areas and premium family-home expectations can alter roof forms, glazing strategy, footprint and how openings are stitched into the existing structure.
We handle the full sequence — architecture, planning, structural coordination and construction — across Chelsea, Fulham, Kensington, and Wimbledon and the wider South West London market, so rear, side-return and wraparound projects stay commercially and technically aligned.
Each extension type suits different house layouts, plot shapes and budgets. We design and build all four — and advise honestly on which delivers the best return for your property.
Full-width or partial-width extension to the rear of the property. The workhorse of London extensions — creating open-plan kitchen-diners with direct garden access.
Infilling the narrow alley alongside Victorian and Edwardian terraces. London's most popular extension type — doubling kitchen width and creating a dramatic sense of space with a glazed roof.
Combining rear and side-return extensions into an L-shaped addition. Creates the maximum ground-floor space — typically 25–45 sqm — for a large open-plan kitchen-diner-family room.
Two-storey addition providing extra space on both ground and first floors. Typically a kitchen extension below with a bedroom or bathroom above. Requires planning permission in most cases.
A clear, structured process that takes the uncertainty out of extending your home.
We visit your property, measure the site, assess the garden, check party wall situations and discuss your brief in detail. We identify whether your extension falls within permitted development rights or requires planning permission, and flag any conservation area, Article 4 or tree preservation order constraints. You receive a written feasibility assessment with an indicative budget and recommended approach within 48 hours.
Our architects produce the extension layout with 3D visualisations. Structural engineers design the steelwork, foundations and connection details. We submit planning applications or lawful development certificates, building regulations packages and party wall notices in parallel. For design-and-build projects, the kitchen design, lighting scheme and material selections run concurrently so everything is resolved before construction starts.
Foundations are excavated and poured (typically strip or trench-fill), walls built to DPC level, floor slab laid and the structural shell erected — blockwork walls, steel beams, lintels and the roof structure. The opening between the existing house and the new extension is formed, with temporary propping supporting the existing structure until the steel beam is in position. Once the roof is weathertight, the extension is sealed and internal works begin.
Insulation, plasterboarding, first fix electrics and plumbing, underfloor heating, window and door installation, kitchen fit-out, tiling, flooring, second fix carpentry, painting and decoration. Bi-fold or sliding doors are installed connecting the extension to the garden. External works — patio, drainage, landscaping — complete the project. Building control conducts the final inspection and issues the completion certificate.
Guide prices for London house extensions. All prices are fixed and include design, engineering, planning, full build and decoration.
Infilling the side alley with a glazed roof. Doubles kitchen width and creates a bright, open-plan ground floor. 8–15 sqm added.
Full-width or partial rear extension with bi-fold doors to the garden. Creates a generous kitchen-diner-living space. 15–30 sqm added.
Combined rear and side extension creating an L-shaped addition. The largest single-storey extension option. 25–45 sqm added.
Two-storey extension — kitchen below, bedroom or bathroom above. Best sqm/cost ratio but requires full planning permission. 30–60 sqm total.
What separates a Hampstead Renovations extension from a standard builder's quote.
Every extension is designed by a RIBA architect to suit your specific house, site and lifestyle. No templates, no catalogue layouts — a bespoke design that maximises light, space and the connection between your home and garden.
Architects, structural engineers, planning consultants, party wall surveyors and build teams all under one roof. No subcontracted design, no outsourced engineering, no coordination gaps between separate firms. One team, one contract, one accountable party.
The price we quote is the price you pay. Not an estimate with provisional sums. Not a price that escalates when you choose your fixtures. A fixed, agreed total covering design, engineering, the full build and every material specified in the contract.
We've secured planning approvals across every inner London borough — including conservation areas in Camden, Islington, Westminster and Haringey with the most restrictive policies.
We maximise what can be achieved under PD rights — including the larger home extension scheme (up to 6m rear on terraces, 8m on detached) — avoiding planning costs and delays where possible.
Structural glass roofs, frameless glass corners, slim-profile aluminium bi-folds and floor-to-ceiling fixed glass. We design extensions that flood the ground floor with natural light.
Most extensions are kitchen-led. Our kitchen designers work alongside the architect from day one, ensuring the kitchen layout, island position and appliance locations drive the extension geometry — not the other way round.
RICS surveyors handle all party wall notices and agreements in-house. For terraced and semi-detached extensions, party walls are always a factor — our experience streamlines the process.
We install wet or electric underfloor heating beneath extension floors as standard on most projects — eliminating radiators and freeing up wall space in the new room.
In sensitive settings, we design extensions that satisfy conservation officers — using appropriate materials, roof forms and detailing that complement the existing building's character.
Patio, drainage, garden reinstatement and boundary work are part of the fixed-price contract — not treated as extras that inflate the final bill after the extension is built.
Selected house extensions completed by our team across London.
6m full-width rear extension with structural glass roof and 4m bi-fold doors. Open-plan kitchen-diner with island under permitted development.
L-shaped wraparound creating 38sqm open-plan kitchen-diner with glazed side return and full-width rear doors. Planning approved in conservation area.
Two-storey rear extension — open-plan kitchen below, master bedroom with en-suite above. Full planning permission secured through Haringey.
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Visit Hampstead On Demand →The side-return extension completely transformed our ground floor. What was a dark, narrow kitchen is now a bright, open-plan room with a huge skylight running the full length. The architect suggested the glazed corner detail that everyone comments on — that's the difference between a design-and-build firm and a standard builder's extension.
We were worried about getting planning for a wraparound in a conservation area. Hampstead Renovations designed an extension with zinc cladding and a recessed glass link that the conservation officer praised as exemplary. The build was immaculate and the fixed price held exactly — not a single extra charge in 14 weeks of construction.
Having the kitchen designer, architect and structural engineer all working together from the start meant our extension was designed around our kitchen — not the other way round. The island position, the sink location, the pendant lighting — everything was resolved before the builders dug the foundations. No compromises, no changes on site.
Everything London homeowners ask about house extensions.
Use the area pages below to jump straight to the streets, councils and property types most relevant to your project.
Side return, rear and wraparound projects for premium townhouses, listed interiors and basement-led schemes.
Side return, rear and wraparound projects for terrace houses where side-return and loft projects unlock family space.
Side return, rear and wraparound projects for high-value homes, mansion flats and heritage-sensitive renovations.
Side return, rear and wraparound projects for wide plots, substantial family houses and ambitious rear additions.
Side return, rear and wraparound projects for Victorian houses, riverside flats and extension-ready family homes.
Side return, rear and wraparound projects for period terraces, townhouse upgrades and compact urban footprints.
Book a free consultation to discuss your south west london project. We will assess feasibility, planning context, likely budget and the most efficient route from design to construction.
We visit your property, measure the site and provide a clear assessment of what's achievable — completely free.
Book Free ConsultationGuide prices including VAT. Final costs depend on specification and site conditions.