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London — Tier-1 Pillar

London Structural Steel — RSJ, Engineer's Calcs, Building Control

London structural steel reality. RSJ or UB/UC beam for load-bearing-wall removal, Chartered Structural Engineer's calcs, Approved Document A Building Control, intumescent fire protection, CE/UKCA marked steel, Party Wall on shared structures. £2K-£15K typical.

~2 min read·Updated 2026-04-23

Inserting a rolled steel joist (RSJ) or Universal Beam (UB) to remove a load-bearing wall is the highest-volume London structural intervention. A typical knock-through between a kitchen and a dining room, or a rear-wall opening for bi-fold doors, needs a Chartered Structural Engineer's calculations, a Building Control submission (Full Plans or Building Notice), CE or UKCA-marked steel, and intumescent fire protection to meet Approved Document B 30-minute or 60-minute fire resistance.

The structural calculation establishes beam size, bearing lengths, padstones, and temporary-works requirements. For a typical Victorian terrace internal knock-through, a 203 x 133 UB is common; for a rear-wall opening spanning 4-5 m, 254 x 146 UB is typical. Padstones transfer beam reactions into the masonry below and must be sized against the local bearing capacity.

Building Control submits Full Plans for most structural work; Building Notice is possible for straightforward single-beam jobs but means the inspector sees the work only during execution rather than at design stage. On Party Wall structures (the standard case for terraces), Section 2 notices are mandatory.

AskBaily routes London structural steel to Chartered Structural Engineer-designed installations with Building Control sign-off, intumescent fire protection, and Party Wall awards where applicable.

Structural steel compliance checklist

  • Engineer's calcs. Chartered Structural Engineer (MIStructE). PI insurance.
  • Building Control. Full Plans or Building Notice. Approved Document A.
  • Fire protection. Intumescent coating or boxed-in plasterboard to achieve 30/60-min resistance.
  • CE / UKCA mark. Steel mill certification.
  • Party Wall. Section 2 notices on shared structures.
  • Temporary works. Acrow props and needles during beam insertion.

Frequently asked questions

Do I need a structural engineer for a London RSJ? Yes — always. Building Control will not sign off without Chartered Structural Engineer's calculations. The engineer specifies beam size, bearing lengths, padstones, and temporary works.

How much does a London structural steel installation cost? £2,000-£5,000 for a typical internal knock-through with single UB 3-4 m span. £5,000-£10,000 for a rear-wall opening with twin UBs or a longer span. £10,000-£25,000 for complex multi-beam schemes with cantilever or transfer structure.

What is intumescent protection? A coating that expands when heated to protect the steel from rapid temperature rise in a fire. Achieves 30-min or 60-min fire resistance per Approved Document B.

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