Structural Alterations in Westminster | RCB Design & Build
Structural alterations are the smallest of our project categories but the highest-value per day on site — typically opening through a load-bearing wall or upgrading a beam to support a new use. RCB Design & Build delivers structural alterations projects right across Westminster (W1) from our Dartford base — typically on site within 48 hours of enquiry, with a fixed written quotation in 5 working days. Our typical structural alterations project in Westminster costs between £12,000 and £87,000 in 2026, with most Georgian terraces and mansion blocks landing around £49,500. We are FMB, TrustMark, Checkatrade and TrustATrader accredited and operate as a Principal Contractor under CDM 2015.
Heritage refurbishment, structural alterations and amenity work. Almost every property is listed or in a CA. Working out of Westminster City Council's area, we know the planners, the local building inspectors, and the named conservation officers — that personal relationship cuts weeks off the consenting timeline. Our typical Westminster project is on Georgian terraces within easy reach of Mayfair or Marylebone, and we work with a small panel of trusted London-area subcontractors we have used for years.
What's included in our structural alterations price
Structural engineer drawings, Building Control submission, steel beam supply (UB/UC sized for span), props during works, padstones, brickwork making good, plaster and skim. Most jobs complete in 5–10 working days. Our written quotation covers labour, first-fix materials, project management, scaffolding, skips, Building Control fees and statutory inspections. Second-fix materials (kitchens, bathrooms, flooring, tiles, paint, sanitaryware) are supplied by the client as a deliberate cost-control measure — this typically saves homeowners £3,960–£7,425 in trade markup. We exclude planning fees, party-wall surveyor fees and structural engineer drawings, which we coordinate at cost.
Westminster planning, party walls and Building Regs
Westminster City Council enforces the strictest planning regime — most buildings need LBC for any external change. Always overspec the steel by 10–15% rather than hit the calc exactly — the marginal cost is trivial vs. deflection complaints two years on. Note that Westminster has multiple conservation areas — design must match prevailing materials, roof shape and fenestration. Party Wall Awards are typically needed for any excavation within 3 metres of a shared wall — we coordinate the surveyor and serve notices. Building Control is lodged at the start, with inspections at foundation, damp-course, pre-plaster and completion stages.
Timeline and process for Westminster projects
Structural alterations typically run 1–2 weeks on site once steels are designed and ordered. Notifiable building works require Building Control inspection before plaster goes back. We hold a weekly call with the client throughout, send a written progress report with photos every Friday, and the lead PM is always reachable on WhatsApp. From W1 postcodes we can have someone on site within 48 hours of a phone call.
Guarantees and after-care
Every project we deliver in Westminster is backed by a 12-month workmanship guarantee. Where we install manufacturer-warranted systems (roofing membranes, windows, MVHR), the manufacturer warranty (typically 10–25 years) runs alongside. As an FMB member we can also arrange an FMB-backed 2-year insurance warranty on qualifying Westminster schemes — worth considering for any project above £50,000.
Structural Alterations cost in Westminster — 2026 price guide
Project size
From
To
Single doorway opening
£12,000
£18,000
Standard load-bearing wall
£18,000
£30,000
Multiple beams / large knock-through
£30,000
£48,000
Whole-storey structural strip
£48,000
£72,000
Indicative Westminster (W1) ranges for 2026. A site visit firms the figure to +/-5%.
Frequently asked questions
How much does a structural alterations cost in Westminster in 2026?
Typical Westminster pricing ranges from £12,000 to £87,000 depending on size, finish and site complexity. Westminster sits in the upper-tier London market so labour rates run 15–25% above outer-borough averages. A free site visit firms the number up to ±5%.
How long will a structural alterations take in Westminster?
Allow 6–12 weeks of design, planning and procurement before work starts, then a project-dependent build phase. Structural alterations typically run 1–2 weeks on site once steels are designed and ordered. Notifiable building works require Building Control inspection before plaster goes back. We share a Gantt-style schedule with every quotation.
Do I need Building Control for a structural alteration in Westminster?
Yes — any change affecting structural support is notifiable. We submit a Building Notice and arrange the inspector. Expect 1 visit before steel install, 1 after.
Which areas of Westminster do you cover?
We cover all of W1 and the surrounding London postcodes from our Dartford base. Recent projects sit close to Mayfair and Marylebone. Anywhere within 45 minutes of Dartford is comfortably inside our core delivery zone.
Is RCB insured?
Yes — we hold £5 million Public Liability, £10 million Employer's Liability, full Contract Works insurance and Professional Indemnity. Certificates are provided with every quotation.
How do I get a quote?
Use the free instant calculator at /quote for a 60-second ballpark, configure your project in detail at /configure, or call +44 7359 872594. We respond to every enquiry within 4 working hours.