Luxury Builders in Belgravia
High-specification refurbishment, listed building work and basements in Belgravia, built to your architect's drawings under a JCT contract.
Builders in Belgravia, SW1
Belgravia was laid out from the 1820s by Thomas Cubitt for the Grosvenor family: stucco-fronted terraces around Belgrave, Eaton and Chester Squares, with mews houses behind. It sits in the City of Westminster, most of it lies in the Belgravia conservation area, it has its own Neighbourhood Plan, and many of the houses are listed, so most work beyond decoration needs consent before it starts.
Alstruct takes on this work as main contractor. We price from your architect's or interior designer's drawings and specification after a site visit, build under a JCT contract for a fixed, itemised sum, and start controlled work only once the consents it needs are in place. Our published case studies are elsewhere in London (Archway, Bow, Limehouse, Golders Green, Cockfosters and Stratford), not in Belgravia.
The high-specification refurbishment section below sets out the consents a Belgravia project usually needs, including Grosvenor's consent, and the published rates we use as a cross-check. If you already have drawings, see how pricing from your drawings works.
How we take on work in Belgravia
- Main contractor under a JCT contract, as standard
- Fixed, itemised price from your design team's drawings, after a site visit
- Written variation instructions, with any extra cost confirmed before the work is done
- A dedicated site manager coordinating the trades and Building Regulations inspections
- £10M public liability insurance
- CHAS Elite, Constructionline Gold & FMB accredited
- 10-year workmanship warranty
- Drawings and photos can be attached to the enquiry form (PDF, JPG, PNG, HEIC, DWG)
Construction Services in Belgravia
Refurbishment in Belgravia
Whole-house and apartment refurbishment in Belgravia: structural alterations, new services, joinery, stone and decoration, built to your designer's schedule under one JCT contract.
Learn more →Basement Conversions in Belgravia
Cellar conversions and single-storey basement excavation where Westminster's basement policy and the building's listing allow, including underpinning, waterproofing and fit-out.
Learn more →Extensions in Belgravia
Rear and closet-wing extensions built to consented drawings, with the steelwork, glazing and finishes your architect specifies.
Learn more →Loft Conversions in Belgravia
Mansard and roof-level conversions where planning and listed building consent allow, including the structural work, stairs and fit-out.
Learn more →Structural Works in Belgravia
Underpinning, foundations, drainage and structural alterations, designed by your engineer and inspected by building control.
Learn more →Hard Landscaping in Belgravia
Stone paving, garden walls, steps and front-area repairs, usually carried out as part of a wider refurbishment.
Learn more →House and kitchen extensions in Belgravia
Belgravia is Grade II listed stucco terraces on the Grosvenor estate, mews houses and mansion flats around Eaton Square, Chester Square and Elizabeth Street. Extensions in Belgravia mean lower-ground and basement work, rear closet-wing infills and mews conversions, needing planning permission, listed building consent where the house is listed, and often estate approval.
As a guide, a well-built single-storey rear or side-return extension in Belgravia costs around £2,500–£4,000 per m² including structure, glazing and finishes, so a typical 25–30 m² kitchen extension lands between £75,000 and £120,000. Our house extension cost guide explains what moves the price. Most of Belgravia is in the Belgravia conservation area, with edges in the Grosvenor Gardens, Knightsbridge and Knightsbridge Green conservation areas, and a high share of buildings are listed, so most external changes need Westminster City Council's approval and, within its scheme or under your lease, Grosvenor's. We confirm permitted development rights at the first visit and handle any application to Westminster City Council through our design team.
Planning a kitchen extension? See our kitchen extensions page for layouts, glazing and costs.
Loft conversions in Belgravia
Roof alterations are tightly controlled: mansard roof extensions and reconfigured top floors are possible on some terraces and mews, subject to planning permission and, where the house is listed, listed building consent.
In London a Velux conversion costs £25,000–£45,000, a dormer loft with a bedroom and en-suite £45,000–£75,000 and a mansard £60,000–£100,000+; our loft conversion cost guide sets out what is included. We survey the roof structure, head height and stair position before we quote a Belgravia loft, so the figure reflects the actual roof rather than an assumption.
Renovations and refurbishment in Belgravia
Belgravia projects are high-specification refurbishments of townhouses and lateral apartments: joinery, stone, lime plaster and full services replacement. Typical Belgravia refurbishments include structural openings with steel beams, new kitchens and bathrooms, rewiring, heating and period repairs such as sash windows, cornices and floors. Our Victorian terrace renovation cost guide gives realistic budgets, and every project runs on a JCT contract with a written specification and our 10-year workmanship warranty.
High-specification refurbishment in Belgravia
Belgravia is stucco-fronted terraces around Eaton Square and Chester Square, with mews houses behind. Refurbishment here is rarely about floor area: it is new services threaded through old fabric, joinery and stone to a designer's schedule, and often work at lower-ground or basement level.
Westminster City Council lists Belgravia among its conservation areas, and the area has had its own Neighbourhood Plan since March 2024. The council states that listed building consent is required for any works affecting a listed building's special interest, interior or exterior, and that working without it is a criminal offence.
The Grosvenor estate is a second layer. Its published guidance says freehold owners need Grosvenor's consent under the Belgravia Estate Management Scheme alongside statutory permissions, and that a scheme can have planning permission and still be refused by the estate. In Belgravia only, changes to internal load-bearing walls need its consent too. Leaseholders should check their alterations clause.
Basements are where the rules bite hardest. Westminster's City Plan supports basements that extend beneath no more than 50% of the garden land and no more than one storey below the lowest original floor level; Grosvenor says basements are generally discouraged under mews houses. The council's Code of Construction Practice covers any new or extended basement and bars piling, excavation and demolition on Saturdays. Before work starts, your team will need:
- Planning permission and listed building consent, where the works need them
- Grosvenor's written consent, or your landlord's under the lease
- Party wall awards where the Act applies
- For a basement, a Construction Management Plan under the council's Code
We take this work on as main contractor under a JCT contract, building to your architect's or interior designer's drawings for a fixed, itemised price, with £10M public liability insurance, CHAS Elite, Constructionline Gold and FMB accreditation and a 10-year workmanship warranty. See how pricing from your drawings works, or our high-end residential builders page.
As a cross-check only, our guides give £3,200–£4,500/m² (high-spec) and £4,500–£6,000+/m² (top tier) for extensions, £4,500–£6,500 per square metre for a full basement excavation and £1,100–£1,600/sqm for a high-specification renovation of a Victorian terrace. A listed Belgravia house is priced from its drawings, not a rate card. Extension figures include VAT; basement and renovation figures exclude it.
Guides for homes in Belgravia
For the period townhouses, mews and conservation areas of Belgravia, our most useful guides are mansard loft conversion costs, basement conversion costs, extending in a conservation area, leaking lead roof valleys and damp basements and tanking.
Planning approvals in Belgravia
Westminster City Council approved 83.1% of householder planning applications decided between September 2025 and August 2026, against a London average of 85.8%; a typical decision took about 11.5 weeks from validation. Extensions were approved 81.8% of the time.
See how every London borough compares, including loft and extension approval rates, in our 2026 London planning approvals study.
Alstruct projects near Belgravia
Notting Hill Villa, W11
Every lead valley renewed on a period villa roof, and the basement store waterproofed and reinstated.
View project →Hammersmith Terrace, W6
A terraced house reworked from the lower ground floor to a new loft floor, with a new steel frame and a full refit.
View project →Archway Victorian Terrace, N19
Full Victorian terrace renovation and rear extension with triple glazing and aluminium sliding doors.
View project →Beyond the projects above, we have recent and current sites in W4, W14, NW8, NW6, W12 and SW6 within about five miles of Belgravia, and we work across every London borough from our office in South Woodford, E18. See all completed projects →
Common questions about building in Belgravia
Do I need planning permission for an extension in Belgravia?
Houses, though not flats or maisonettes, keep national permitted development rights for a single-storey rear extension of 3m (attached) or 4m (detached), up to 6m or 8m through prior approval, and most rear dormers within 40 cubic metres on a terrace or 50 elsewhere. Most of Belgravia is in Westminster City Council's Belgravia conservation area, with edges in Grosvenor Gardens, Knightsbridge and Knightsbridge Green. There, rear extension rights remain, but side extensions, two-storey rear extensions, cladding and roof additions need permission. A city-wide Article 4 direction means every basement needs planning permission.
What does Westminster City Council expect for basements in Belgravia?
Westminster's City Plan Policy 50 supports a basement only where it is no more than one storey below the lowest original floor, goes under no more than 50% of the garden, leaves an undeveloped margin round the boundary and keeps at least 1m of soil plus a 200mm drainage layer on top. For listed houses the basement must not unbalance the original hierarchy of spaces where that matters to the building's significance. The council's Code of Construction Practice treats basement excavation as a Level 3 project, so a countersigned Appendix A checklist goes in with the planning application and a Construction Management Plan is needed before work starts.
What does a mansard loft conversion cost in Belgravia?
Our published London figures put a mansard loft conversion at £60,000–£100,000+ including VAT, with prime central schemes at £120,000–£150,000. Belgravia's stucco terraces and mews houses tend to sit at the upper end, because listed fabric, lead work and access on a narrow street add cost, and a listed house is always priced from its drawings. Our mansard loft conversion cost guide explains what is included and what moves the figure.
Which Alstruct projects are nearest to Belgravia?
The nearest is Notting Hill Villa, W11, about 2.5 miles away, where every lead valley on a period villa roof was renewed and the basement store waterproofed and reinstated. Hammersmith Terrace, W6, about 3.2 miles away, was a terraced house reworked from the lower ground floor to a new loft floor, with a new steel frame and a full refit. Archway Victorian Terrace, N19, about 4.8 miles away, was a full Victorian terrace renovation and rear extension with triple glazing and aluminium sliding doors.
Which parts of Belgravia do you cover?
We cover all of Belgravia in SW1, from Belgrave, Eaton and Chester Squares to Elizabeth Street and the mews houses behind the main terraces. Planning decisions here are made by Westminster City Council. We work from our office in South Woodford, E18, about 10 miles away, and we also have local pages for Chelsea, Mayfair and Kensington.
Nearby areas we cover
Alstruct works across every London borough. Here are areas close to Belgravia with dedicated local pages: