Steel Beam (RSJ) Costs UK — What to Charge to Supply & Fit One in 2026

RSJ, UB or UC — What Are You Actually Fitting?

"RSJ" (rolled steel joist) is the term most customers and many builders still use for any structural steel beam, but the steel your engineer specifies is usually a Universal Beam (UB) or, less often, a Universal Column (UC) section. The distinction matters when you order steel: UBs are deeper and designed to carry load over a span, while UCs are squarer and used where headroom is tight or where the section doubles as a column. The fabricator works to the engineer's specified size — for example a 203x133 UB or a 254x146 UB — so always quote off the structural calculations, never off a guess.

The headline point for pricing: the raw steel is often only £150–£600 of a job that bills several thousand pounds. The value you're charging for is the structural risk, the labour of propping and inserting the beam safely, the masonry support, and the making good afterwards.

What Affects the Price of a Steel Beam Job

Two beam installations that look similar to a homeowner can differ by thousands of pounds in cost. These are the factors that move the number:

• Beam size and span: A longer span needs a deeper, heavier section and stronger bearings. A 2m beam over a doorway is a different job to a 5m beam spanning a full reception wall.
• Single vs double beam: Wide openings or heavy loads above often need two beams bolted together with spacers, or a beam plus a goalpost frame. This doubles the steel and roughly doubles the lifting and fixing labour.
• Padstones and bearings: The beam ends bear onto padstones (precast concrete or engineering brick) sized by the engineer. These spread the load into the supporting masonry and are non-negotiable.
• Whether the wall is genuinely load-bearing: If the wall carries floor joists or roof above, the structural calcs, propping and Building Control involvement all become essential — and that's where most of the cost sits.
• Propping and temporary support: Before the wall comes out, the load above must be carried on Acrow props and strongboys (or needles through the wall for upper-floor loads). Getting this wrong is the single biggest safety risk on site.
• Access: Carrying a 200kg beam through a terraced house with no rear access is a manual-handling job that adds hours. A large beam may need a crane or telehandler and a clear lift path.
• Masonry support during install: Brickwork above the opening must be cut and supported carefully so it doesn't collapse before the beam is seated and pinned up.
• Making good: Plastering, re-skimming, re-laying flooring, boxing in the steel and fire protection (intumescent or boarding) all add up after the steel is in.

Typical Cost Tiers — Supplied and Fitted

The figures below are for the beam supplied and installed, including propping, padstones and basic making good, but excluding the structural engineer and Building Control fees (covered separately below). Adjust upward for London and the South East.

Small, Simple Beam — Single Opening or Doorway

A short beam (typically 1.5–2.5m) inserted over a new internal doorway or a single small opening, where the load above is modest and access is straightforward. Minimal propping, a single beam, two padstones.

• Supplied and fitted: £1,200–£2,500

Typical Knock-Through — Single Reception Wall (~3–4m Span)

The bread-and-butter job: removing a single load-bearing wall between two reception rooms, or between a kitchen and dining room, with a beam spanning around 3 to 4 metres. This involves proper propping of the floor and/or roof above, a single beam, padstones both ends, and a fair amount of making good.

• Supplied and fitted: £2,500–£5,000

Large or Double-Beam Opening / Steel Goalpost Frame

Wide openings (typically 5m+), removal of a structural wall under significant load, double beams bolted together, or a full steel goalpost frame for bifold or sliding doors in a rear wall. These jobs often need needling, heavier propping, sometimes craning the steel into position, and substantial making good.

• Supplied and fitted: £5,000–£10,000+

The Structural Engineer and Building Control Costs

These are separate professional fees, and they apply to almost every beam job involving a load-bearing wall. Quote them as their own line items so the customer understands they are third-party costs and you're not marking them up unfairly.

Structural engineer's calculations: £300–£800. The engineer visits, assesses the loads, specifies the beam size, the padstones and the bearing details, and produces stamped calculations. Building Control will not sign off without these. For a simple single beam the fee sits at the lower end; for a multi-beam or goalpost design it sits higher.

Building Control approval: £300–£500. Removing a load-bearing wall is notifiable structural work under the Building Regulations. You apply via your local authority Building Control or an approved inspector, they review the engineer's calcs and inspect the beam in place before it's boxed in. Skipping this is not an option — it shows up on surveys when the property is sold and can stall a sale.

UK Rules You Must Factor In

• Building Regulations approval is required for removing any load-bearing wall. The beam must be inspected and signed off, and you'll need a completion certificate for the homeowner's records.
• A structural engineer's calculations are mandatory. Never size a structural beam yourself — the calcs protect you, the customer and the building, and they're what Building Control assess.
• The Party Wall etc. Act 1996 may apply if the beam bears into, or work affects, a wall shared with a neighbour (common in terraced and semi-detached properties). The homeowner must serve notice on the neighbour, typically two months before work starts. Flag this early — it can delay the job and is the homeowner's responsibility, but they'll expect you to know it applies.

The Trades Involved

A steel beam job is rarely a one-person task. Knowing who you need helps you price labour and coordinate the programme:

• Structural engineer — produces the calculations and specifies the steel. Always involved.
• Builder / bricklayer — does the propping, cutting out, beam insertion, padstone bedding, pinning up and making good. This is the core of the job.
• Steel fabricator — supplies and, for larger jobs, drills, plates and powder-coats the beam to the engineer's spec. For a simple beam you may just buy cut-to-length steel.
• Crane or lifting contractor — for heavy beams or restricted access, a telehandler, Hiab or mobile crane may be needed to get the steel into position safely. Budget separately and confirm the lift path.

Quick Reference: Steel Beam Prices UK 2026

Worked Example — Single 3.5m RSJ Knock-Through

A homeowner wants to remove the load-bearing wall between their lounge and dining room to create one open-plan reception space. The opening is 3.5m wide, the wall carries first-floor joists above, and there's reasonable side access. Here's how the quote stacks up:

• Structural engineer's visit and calculations: £450
• Building Control application and inspections: £400
• Steel beam (254x146 UB, ~4m cut to length) supplied: £350
• Padstones (pair) and fixings: £90
• Acrow props, strongboys and consumables (hire): £160
• Labour — propping, cutting out, beam insertion, pinning up (2 builders, ~3 days): £2,000
• Making good — plastering, boxing in the steel, fire protection: £700
• Waste removal and skip: £280

That comes to roughly £4,430 including the professional fees, or about £3,580 for the beam supplied and fitted excluding the engineer and Building Control — squarely inside the £2,500–£5,000 knock-through tier. Add your margin and overheads on top of the trade costs, and present the engineer and Building Control as clearly separate items so the customer sees exactly what they're paying for.

Where Builders Lose Money on Steel Beam Jobs

The most common pricing mistakes on RSJ work are predictable, and they're easy to avoid once you know them:

• Underestimating making good. The steel goes in quickly, but plastering, flooring, boxing in and fire protection often cost as much as the structural work itself. Price the whole job, not just the beam.
• Forgetting the professional fees. If you absorb the engineer or Building Control costs instead of passing them on, you can wipe out your margin. Always quote them separately.
• Ignoring access. A heavy beam through a tight terraced house, or one needing a crane, can add a day of labour and a hire bill that wasn't in your original number.
• Skipping the Party Wall check. On terraces and semis, a missed Party Wall notice can halt the job and damage your reputation. Raise it at quoting stage.

Quote off the engineer's calcs, itemise the professional fees, allow properly for propping, access and making good, and steel beam work becomes one of the most reliably profitable jobs on your books.