Builders in Westminster: Conservation Area & Basement Specialists in W1, SW1, W2 & NW8
Soraiz Builders carries out extensions, renovations and full-trade building work across Westminster, from the Georgian townhouses and mews of Mayfair and Marylebone to the stucco squares of Belgravia and Pimlico and the white-stucco terraces of Bayswater. Westminster Abbey itself was built on a gravel island left by the ancient River Tyburn, and engineers used compensation grouting to protect the Treasury and Big Ben when the Jubilee Line Extension tunnelled beneath the borough in the 1990s. Getting the ground right matters here as much as the planning route. Call Shamraiz Hussain's team today for a written quote within 2 hours.
Soraiz Builders provides extensions, renovations, plumbing, electrics and full building work across Westminster, including Mayfair, Marylebone, Belgravia, Pimlico and Bayswater. The borough has 56 conservation areas and 4,003 listed buildings, the highest concentration of any local authority in England, so almost every property here needs careful planning-history checks before any design work starts. Soraiz Builders offers a written quote within 2 hours of enquiry.
Widespread flooding hit Pimlico in June 2016 after heavy rainfall, and Victoria station, used by around 75 million passengers a year, sits inside Westminster's own Flood Zone 3, the council's highest flood-risk category.
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Housing Stock by Area
What kind of houses does Westminster have?
The City of Westminster runs from Bayswater and Paddington in the west, through Mayfair, Marylebone and Soho in the centre, down to Belgravia, Pimlico and Victoria in the south, and its housing stock is dominated by Georgian and Victorian estate-built terraces, mews houses and mansion blocks rather than one uniform type.
- Mayfair and Marylebone (W1): Georgian and Victorian townhouses, mews homes and grand mansion blocks on some of the most tightly estate-managed streets in the country.
- Belgravia and Pimlico (SW1): Grade II* stucco squares in Belgravia and a grid of listed Georgian terraces in Pimlico, both largely inside conservation areas.
- Bayswater and Paddington (W2): white stucco terraces around Lancaster Gate, largely within conservation areas.
- St John's Wood and Regent's Park (NW8, NW1): Victorian villas, large townhouses and leafy streets, popular with families.
- Soho and Covent Garden (W1, WC2): a denser mix of Georgian and Victorian buildings, many in mixed residential and commercial use.
Common problems we see in Westminster properties
Westminster's ground, its heritage density and its basement planning regime all shape how we approach a job here more than in most boroughs.
- London Clay 70 metres down, gravel closer to the surface: in central Westminster, London Clay sits around 70 metres below ground, with the ancient River Tyburn having left gravel eyots, small former islands, closer to the surface. Westminster Abbey itself was built on one of these gravel islands. Foundation and basement design needs to account for this layered ground rather than a standard London Clay assumption.
- Compensation grouting near major infrastructure: when the Jubilee Line Extension tunnelled beneath the borough in the 1990s, engineers used compensation grouting to protect buildings including the Treasury and Big Ben from ground movement, a real precedent for how seriously ground movement is taken here.
- A borough-wide basement Article 4 Direction: since 31 July 2016, every basement of any size needs full planning permission, and City Plan Policy 45 limits new basements to a single storey below the original lowest floor and no more than 50% of the garden, with Westminster and neighbouring Kensington and Chelsea having effectively prohibited new two-level basements.
- Dense terracing and party walls: Mayfair, Marylebone, Belgravia and Pimlico's terraces sit close enough together that nearly every rear extension, loft conversion or basement falls within 3 metres of a neighbour, triggering the Party Wall etc. Act 1996.
Local Area
Local landmarks and transport links relevant to building work in this area.
- Westminster Abbey (UNESCO World Heritage Site, built on a gravel island left by the ancient River Tyburn)
- The Houses of Parliament and Big Ben (the Elizabeth Tower, part of the Palace of Westminster)
- Buckingham Palace
- Regent's Park
- Belgrave Square (the grand Grade II* stucco heart of Belgravia)
Victoria, Paddington, Marylebone, Baker Street, Oxford Circus
Where We Work in Westminster
Where we work in Westminster
We cover the whole City of Westminster, W1, SW1, W2, NW1 and NW8, including:
- Mayfair and Marylebone (W1): Georgian and Victorian townhouses and mews homes on some of the most tightly estate-managed streets in the country.
- Belgravia and Pimlico (SW1): Grade II* stucco squares and a grid of listed Georgian terraces.
- Bayswater and Paddington (W2): white stucco terraces largely within conservation areas.
- St John's Wood and Regent's Park (NW8, NW1): Victorian villas and large townhouses on leafy streets.
- Soho and Covent Garden (W1, WC2): a denser mix of Georgian and Victorian buildings in mixed residential and commercial use.
Working around Westminster's parking and access
Westminster has some of the most extensive Controlled Parking Zone coverage of any London borough, and a skip licence costs £91 a month, rising from March 2026, with skips placed inside a controlled bay needing a separate parking suspension arranged by the skip company at the same time. We arrange builder's parking permits and skip licences well in advance so materials and skips don't sit waiting on day one.
Check If We Cover Your Westminster Street
Get a Free QuotePlanning & Conservation
What to check before starting building work in this borough.
Westminster City Council
Planning portal: View planning permission information
Planning permission and conservation areas in Westminster
Westminster has 56 conservation areas, including Mayfair, Belgravia, Marylebone, Pimlico, Soho, Covent Garden and St John's Wood, and 4,003 listed buildings, the highest concentration of any local authority in England. Because so much of the city lies within a conservation area, a full planning application, and often listed building consent, is usually required even for modest external works in Belgravia, Mayfair, Pimlico or Bayswater.
Westminster has also removed permitted development rights entirely in 8 conservation areas, meaning planning permission is required even for specified minor alterations there. Standard single-storey rear extensions outside a conservation area and within national permitted development size limits can still keep permitted development rights, but with heritage coverage this dense, that route is not available at most Westminster addresses. Before planning any external work, check your address against the council's conservation area and listed building records.
Basements: a borough-wide Article 4 Direction since 2016
A city-wide Article 4 Direction in force since 31 July 2016 removes all permitted development rights for basement development, so every basement excavation needs full planning permission regardless of size. City Plan Policy 45 further limits new basements to a single storey below the lowest original floor and no more than 50 percent of the garden area, and requires a Basement Impact Assessment. Westminster and neighbouring Kensington and Chelsea have effectively prohibited new two-level basements as a result.
Realistic planning timescales
Westminster's average processing time across all applications runs to 11.9 weeks, and the borough's householder approval rate, 81.3 percent over the year to Q1 2026, ranks among the lowest of any London borough, sixth-lowest of 33, below the London average of 85.6 percent. The council's own heritage density, with the highest concentration of listed buildings of any local authority in England, is the most likely driver. We build a realistic timeline and a properly prepared, heritage-aware application into every Westminster quote.
What normally needs planning permission in Westminster
- External alterations affecting the appearance of a house inside one of the borough's 56 conservation areas
- Any basement excavation, of any size, anywhere in the borough, under the 2016 Article 4 Direction
- Specified minor alterations in the 8 conservation areas where permitted development rights have been removed entirely
- Any work affecting a Listed Building, and Westminster has more of these than any other local authority in England
- Works to a tree protected by a Tree Preservation Order, or any tree inside a conservation area
What usually does not
- Internal, non-structural work: new kitchen or bathroom in the same footprint, redecoration
- Standard single-storey rear extensions on an address outside every conservation area, within permitted development limits
- Like-for-like repairs outside conservation areas: matching roof materials, identical window replacements, repointing
What Building Work Costs in Westminster
| Item | Typical Cost | Note |
|---|---|---|
| Single-storey rear extension, per m² (mid specification) | £4,000 - £5,500+ | Among the highest rates of any London borough, reflecting central London land values and heritage detailing costs. |
| Basement extension, per m² (under the garden) | £6,000 - £8,000+ | Before heritage uplifts that apply to most Westminster properties. |
| Basement extension, per m² (under the house) | £8,000 - £12,000+ | New two-level basements are effectively prohibited under City Plan Policy 45. |
| Householder planning application fee | £548 | From April 2026. Applies inside any of Westminster's 56 conservation areas, on any Listed Building, or for any basement scheme under the 2016 Article 4 Direction. |
Services We Provide Across Westminster
Full house renovations across Westminster, from Mayfair townhouses to Pimlico's listed terraces.
Plastering, rendering and stucco repair matched to the original on Westminster's period stock.
Plumbing for extensions, basements and full renovations across the borough.
Central heating and gas work across Westminster, from routine servicing to full system upgrades.
Flat and apartment refurbishment for Westminster's mansion blocks and period conversions.
Why Westminster Homeowners Choose Soraiz Builders
Soraiz Builders & Services Ltd was founded in 2019 by Shamraiz Hussain and has completed 250+ projects across all 32 London boroughs. On a Westminster job, that means treating any basement as a full planning application from day one under the 2016 borough-wide Article 4 Direction, checking listed building and conservation area status carefully given the borough holds more listed buildings than any other local authority in England, and planning ground-floor and lower-ground work for real flood risk near Pimlico and Victoria rather than a standard specification. On the Georgian and Victorian terraces of Mayfair, Marylebone and Belgravia we match stucco, brick and joinery to the original rather than a generic modern finish.
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Frequently Asked Questions
Answers to the questions homeowners in this area ask most.
Do I need planning permission for a house extension in Westminster?
Almost certainly, yes. Westminster has 56 conservation areas and 4,003 listed buildings, the highest concentration of any local authority in England, so a full planning application and often listed building consent is usually required even for modest external works. We check your specific address before any design work starts.
How many conservation areas does Westminster have?
Westminster has 56 conservation areas, including Mayfair, Belgravia, Marylebone, Pimlico, Soho, Covent Garden and St John's Wood. The council has also removed permitted development rights entirely in 8 of these, so even specified minor alterations need planning permission there.
Can I build a basement in Westminster?
Only with full planning permission. A borough-wide Article 4 Direction, in force since 31 July 2016, removes all permitted development rights for basement development, and City Plan Policy 45 limits new basements to a single storey below the original lowest floor and no more than 50 percent of the garden. Westminster has effectively prohibited new two-level basements as a result.
Is Westminster at risk of flooding?
Parts of it, yes. Widespread flooding hit Pimlico in June 2016 after heavy rainfall, and Victoria station sits inside the council's own Flood Zone 3, its highest flood-risk category. Basement properties are particularly vulnerable to both surface water and sewer flooding, and drainage connections from basements normally need a one-way valve fitted.
How much does a house extension cost in Westminster?
A single-storey rear extension typically costs £4,000 to £5,500 per square metre or more at a mid specification, among the highest rates of any London borough. Basement space typically runs £6,000 to £8,000 per square metre under a garden, or £8,000 to £12,000 or more under the house itself, before heritage uplifts.
How long does planning permission take in Westminster?
Westminster's average processing time across all applications runs to 11.9 weeks, and the borough's householder approval rate, 81.3 percent, ranks among the lowest of any London borough, below the London average of 85.6 percent. A well-prepared, heritage-aware application matters more here than in most boroughs.
Do I need a Party Wall Agreement for building work in Westminster?
Almost certainly, in the more terraced parts of the borough. Mayfair, Marylebone, Belgravia and Pimlico's terraces sit close enough together that a rear extension, loft conversion or basement can fall within 3 metres of a neighbouring property, triggering the Party Wall etc. Act 1996. Notices need serving at least two months before work starts, and we handle this as part of the project.
Which parts of Westminster do you cover?
We cover the whole City of Westminster, including Mayfair, Marylebone, Belgravia, Pimlico, Bayswater, Paddington, St John's Wood, Soho and Covent Garden, across postcodes W1, SW1, W2, NW1 and NW8.
Why does Westminster have so many listed buildings?
Westminster holds 4,003 listed buildings, the highest concentration of any local authority in England, a result of centuries of estate-managed Georgian and Victorian development across Mayfair, Marylebone, Belgravia and Pimlico that was never comprehensively redeveloped. This density is also the most likely reason the borough's planning approval rate sits below the London average.
Can I build a two-level basement in Westminster or Kensington and Chelsea?
In practice, no. City Plan Policy 45 limits new basements in Westminster to a single storey below the original lowest floor, and neighbouring Kensington and Chelsea applies a similarly strict policy. Both boroughs have effectively prohibited new two-level basements as a result, even though there is no outright numerical ban in either policy.
Why was Westminster Abbey built where it is?
Westminster Abbey was built on a gravel island, known as an eyot, left by the ancient River Tyburn in what was once Thames floodplain. This firmer ground amid otherwise marshy land is part of why this specific site was chosen, and it still shapes how engineers think about ground conditions in this part of the borough today.
Is it more expensive to extend a house in Westminster than other boroughs?
Yes, generally. A single-storey rear extension in Westminster typically costs £4,000 to £5,500 per square metre or more, among the highest rates of any London borough, reflecting central London land values and the borough's dense heritage protection, which usually adds further cost for period-appropriate materials and detailing.
What happened in the June 2016 Pimlico flooding?
Heavy rainfall in June 2016 caused widespread flooding across Pimlico, affecting streets and properties in this low-lying part of the borough. It's one of the reasons Victoria station and the surrounding area now sit inside Westminster's own Flood Zone 3, the council's highest flood-risk category, and why drainage design near here needs proper assessment.
Other London Boroughs We Also Cover
Get a Free Quote in Westminster
Whether you're near Westminster Abbey (UNESCO World Heritage Site, built on a gravel island left by the ancient River Tyburn) or elsewhere in Westminster, Soraiz Builders provides building and renovation services throughout Greater London. A written quote follows within 2 hours.