House
extensions
in Belgravia, SW1X
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 Belgravia house extensions across Eaton Square, Chester Square, Belgrave Square - side-return, rear, wraparound and double-storey additions for Regency Stucco terraces, Grosvenor Estate townhouses and larger family homes where planning strategy, conservation detailing, Party Wall sequencing and structural engineering need handling properly.
House Extensions in Belgravia: What You Need to Know
Every house extension project in Belgravia is designed to respect the Belgravia Conservation Area and the character of Regency stucco terraces, Grosvenor Estate townhouses, prime mansion flats. 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 Belgravia'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.
Ultra-prime Grosvenor Estate neighbourhood with sweeping white stucco crescents. Belgrave Square, Eaton Square, and Chester Square. Westminster conservation area with the highest planning standards. Our extensions in Belgravia use materials and detailing that complement the existing architecture — whether matching traditional brickwork and stonework or introducing high-quality contemporary glazing and zinc cladding.
Almost all of Belgravia lies in the Belgravia Conservation Area, and the concentration of listed buildings here is among the highest anywhere — so a house extension starts life as a conservation argument. The question is never simply how much space can be added, but what the protected terrace, the square and the street elevation will support.
The stock frames the possibilities. Belgrave Square, Eaton Square and Chester Square carry Cubitt's grand stuccoed terraces, Wilton Crescent sweeps in the same white-fronted manner, and behind them sit mews houses and substantial mansion flats. In the mews — compact houses behind the squares — the win is usually clever reconfiguration within a protected, tightly-controlled envelope rather than dramatic outward growth; in the terraces, the case for adding volume is built plot by plot.
For budgeting, London-wide bands put a single-storey rear extension at £71,250–£112,500 excluding VAT and a wraparound at an indicative £100,000–£200,000. In Belgravia the consenting effort sits on top of those numbers, which is why we scope the approvals route before pricing the build. The band tells you where to start; the terrace tells you where you will finish.
House Extensions in Belgravia: Applied to the Local Stock
Almost all of Belgravia lies in the Belgravia Conservation Area with a high concentration of listed buildings. Belgravia sits in the City of Westminster, almost wholly within the Belgravia Conservation Area and largely on the Grosvenor Estate. Belgravia sits inside the Belgravia Conservation Area with a high concentration of listed buildings.
Sources: Westminster City Council — Belgravia Conservation Area mini guide (May 2004) (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
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House Extensions in Belgravia: Questions
Can I get permission to extend a house in Belgravia?
It has to be earned. Almost all of Belgravia lies in the Belgravia Conservation Area with a high concentration of listed buildings, so an extension is judged on conservation terms from the outset — we build the heritage case for the scheme before anything is submitted.
How much does a house extension cost in Belgravia?
London-wide bands give the starting point: £71,250–£112,500 excluding VAT for a single-storey rear extension, and £90,000–£120,000 excluding VAT for a side return. A Belgravia scheme is then priced around its own consents and construction constraints rather than read straight off the band.
Which Belgravia streets hold the houses people extend?
The characteristic addresses are Belgrave Square, Eaton Square, Chester Square and Wilton Crescent — Cubitt's grand stuccoed terraces with mews houses and substantial mansion flats behind them. Each street presents a different rear condition, so the extension answer genuinely varies address by address.
Is extending a listed Belgravia terrace realistic?
Sometimes — but it is heritage work. The monumental white-stucco terraces around Belgrave, Eaton and Chester Squares are mostly listed and leasehold, so any extension is governed by both Westminster and the estate, and the design has to satisfy that double test before it satisfies anyone's appetite for space.
Do Belgravia mews houses have extension potential?
Their potential is mostly inward. The stable mews behind the squares are compact houses that reward clever reconfiguration within a protected, tightly-controlled envelope — we typically find the extra utility through plan and section rather than through added footprint.
Recent Projects Near Belgravia
Local character & heritage: extending in Belgravia
Belgravia sits in the City of Westminster, and extending here means working with grand cream-stucco Cubitt terraces and garden squares around Eaton and Belgrave Squares. Where houses and gardens allow, side-return and rear extensions open up the living space; in the many flats, the equivalent is internal reconfiguration and, where possible, lower-ground additions.
Permitted-development rights are usually restricted in Belgravia's conservation areas, so most extensions need a full householder application, and a very high proportion of buildings are listed and many are now flats or embassies. We design every extension to respect the period frontage and to win consent.
Belgravia heritage & architecture: Conservation areas · Roof developments & conservation · Listed buildings · Renovating a period terrace · Period facades · Facade planning rules
House Extensions in Belgravia: Planning & Local Context
Westminster City Council · SW1X
Planning for house extensions in Belgravia
Rear and side-return extensions are popular in Belgravia, but permitted-development rights are frequently restricted within Belgravia's conservation areas, so most extensions need a full planning application to Westminster City Council with design that respects the prevailing building line and materials.
Westminster City Council context
Belgravia SW1X sits within Belgravia's conservation areas, and Westminster applies a demanding conservation and listed-building regime, and many mansion blocks and townhouses here are listed or sit within tightly controlled estates such as the Grosvenor, Howard de Walden and Crown estates. Belgravia sits within the Grosvenor Estate, which adds a separate licence regime on top of council consent. Our in-house RIBA Chartered Architects prepare and submit every application to Westminster City Council and handle pre-application discussions where early planning advice is useful.
Building Regulations
House Extensions in Belgravia must satisfy Building Regulations — covering structural design to Part A, thermal performance to Part L, and drainage and foundations agreed with Building Control. Our in-house engineers manage Building Control from initial notice to completion certificate.
Recent work & local links
See recent Belgravia work: Carlton Lodge, Belgravia Greville House, Belgravia. Explore our Kitchen Renovation Loft Conversions in Belgravia, or the Belgravia hub · Refurbishment Company in Belgravia.
Our in-house planning team prepares and submits every Westminster City Council application and manages building control end to end. View our planning track record →
House Extensions in Nearby Areas
More Services in Belgravia
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We survey your property, discuss your vision and provide a clear budget framework.