Structural Alterations Soho

With 98% of Soho homes being flats, GS Renovation's structural alterations across W1 mean new openings, replaced joists and supported spans inside apartments. Soho's few houses are terraces; most alterations here happen inside converted or purpose-built blocks, and our founder's 30+ years on the tools include both kinds.

In Soho, a simple new opening starts from £1,500, and underpinning a single elevation typically costs £6,000 to £21,000 (indicative London ranges, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Soho.

How the job runs

1. Free site survey at your Soho address and an itemised quote.
2. The engineer we appoint designs the work, and it is registered with Westminster City Council building control or an approved inspector. On a shared wall you serve the party wall notice as building owner; we supply the drawings.
3. Props and any trial holes first, then the opening, joists or underpinning in the engineer's sequence.
4. Building control inspects each stage before it is covered, then issues the completion certificate.

Structural alterations in Soho's period buildings

Soho's period buildings, most of them now flats over shops, throw up a broad range of structural work. Owners ask us to form new openings between rooms, widen a doorway into a supported opening, replace tired or overloaded floor joists notched by decades of services, and, more rarely and usually as a whole-building job agreed with the freeholder, underpin where settlement has appeared over a century and a half of use. Each of these needs its own engineered solution rather than a one-size-fits-all approach.

We begin with a structural engineer who inspects the property, works out the loads and specifies the fix. A new opening gets a steel lintel or beam bearing onto padstones; replacement joists are sized for the span and grade; underpinning is designed and poured in sequenced bays so the wall above stays supported. Temporary propping holds everything in place until the permanent support is in and load-tested.

Housing in Soho

For the Fitzrovia West & Soho statistical area the Council Tax list gives about 6,840 homes; by type 98% flats and 2% houses, by age 47% post-war, 5% interwar and 48% older than 1919. Most homes here are flats, and structural repair to a block in Soho usually falls to the freeholder under the lease, so it is agreed with them before anything is opened up.

Joining two Soho flats vertically with a new stair

With 98% of Soho homes being flats, one structural alteration open to Soho owners that a street of houses never raises is joining two flats stacked one above the other. That means cutting a stair opening through the floor between them, trimming the joists or slab around it with steel or timber the structural engineer we appoint designs, and forming a new staircase. The floor being cut is also the fire separation between two homes, so the opening changes the layout of both flats and how people escape from them. Westminster excludes layout changes from the building notice route, so the scheme goes in as full plans. Merging two homes into one can also need planning permission, so that is raised with Westminster's planners first.

The outside of the building matters too if the work shows. The Soho Conservation Area was designated in 1969 and extended in 1976, 1979, 1983, 1990 and 2005, and inside a conservation area planning permission is needed for demolition and for some alterations that would not need it elsewhere. Westminster's conservation area audits also identify unlisted buildings of merit. A structural alteration that adds a window, changes a rear wall or alters the roof of a building of merit is designed against the audit entry for it, and consent comes before the engineer's final drawings.

Consents and sign-off in Westminster

Because Soho's buildings share their flank walls with the buildings either side, alterations that touch a shared wall, cut into it for a beam bearing or excavate alongside a neighbour's foundation for underpinning are notifiable under the Party Wall Act. You serve the notices on the adjoining owners as building owner (or your surveyor does) in good time, and we give you the drawings and programme they need and build to any award, which keeps relations calm and stops disputes stalling the works in a densely built W1 street.

Westminster City Council's building control checks each beam, bearing, joist and any underpinning under the Building Regulations, flat or house. Westminster's planners take a view on external changes, and because Soho is a conservation area and flats have no householder permitted development, most external work needs an application; a listed building also needs listed building consent for internal structural work. In a leasehold flat the freeholder's licence to alter comes before any of this, and we supply the engineer's drawings the freeholder's surveyor will ask to see.

• Lintel replacement and repair over failed openings
• New door and window openings in solid masonry
• Trial holes to confirm foundation depth and ground conditions

VOA Council Tax stock of properties, March 2025, for the Fitzrovia West & Soho statistical area, which also covers west Fitzrovia. Counts rounded by the VOA.

Next steps that tend to follow structural alterations in Soho: home renovation in Soho, structural alterations across Westminster, a main building contractor in London, when a wall needs underpinning, our London structural alterations page and Bowing Wall Repair.

Trusted Structural Alterations in Soho

Many Soho flats sit over a shop or bar, so a new opening can mean restoring the fire separation to the floor beneath as well as fitting steel. The engineer we appoint designs it, and our own team books Westminster building control and does the propping and building work itself. Joists, underpinning and propping then follow the engineer's order, the discipline our founder's 30+ years on the tools instil.

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.