Guide

RSJ prices: how much does an RSJ cost in 2026?

Updated 2026-08-14

The steel is the cheap part. Here is the whole RSJ job priced line by line, at typical 2026 quotes, and where not to economise.

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Question 1

What is the clear span of the opening, in metres?

Measure the structural opening. The beam itself will be longer, because it has to bear on masonry at each end; how much bearing, and on what padstone, comes out of the calcs rather than a rule of thumb. Between sizes? Round up.

RSJ installation cost, line by line

Typical 2026 costs for a single domestic beam installation
Line	Typical 2026 cost
Steel beam supplied (small domestic sections)	£150–£300
Structural engineer's calcs	£250–£500
Builder installation: props, padstones, fitting, making good	£1,000–£2,000
Building control application (set by each council, no national scale)	£200–£400 on the 2026 council scales we checked
Typical all-in total	£1,600–£3,200

Steel beam prices per metre

Steel is sold by the metre for each section size, and few stockists publish a price. F H Brundle lists a 178x102x19 universal beam at £35.10 a metre and a 254x102x25 at £46.20 a metre. Both are S355, read on its own product pages on 12 October 2026.

No stockist we read prices the heavier 203 UC, 254x146 and 305 series sections that longer or heavier openings usually need, so treat those as quote-only. Figures, sources and silent stockists are in our UK steel beam cost index.

What moves the price

Beam size and weight: a 3 m beam in the light UC range sits at the bottom of the supplied band; long or heavy UBs cost more to buy and much more to handle, sometimes needing lifting kit.
Access: a beam walked through a front door prices differently from one craned over a roof.
Temporary works: propping two floors while a wall comes out is real labour, and it is where cheap quotes cut corners.
Making good: plastering, flooring and decorating around the new steel often costs as much as fitting it.

Where not to save

The calcs and the sign-off. Skipping the engineer for a span table or a free online calculator saves a few hundred pounds and costs it back with interest:

building control has to be satisfied the beam meets Part A, and in practice will not take a bare span table;
an oversized 'safe guess' beam wastes steel and headroom;
a missing completion certificate resurfaces at sale, when the buyer's conveyancer asks, and the fix is a retrospective regularisation application with opening-up works.

All figures here are typical 2026 quotes and vary by region and job. Treat them as a sanity check on real quotes.

Start with the checker for the indicative range, then have an engineer run the real numbers. That order keeps the total at the bottom of the band.

Get a structural engineer's calcs

Tell us about the opening and we'll introduce you to up to three firms, each a structural engineer who handles domestic beam calcs for jobs like yours.

What's the job?

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Two questions, then the right next step

See the typical section range, then get the calcs that count.

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Questions, answered directly

How much is an RSJ?

The steel is the small part. A stockist's published prices on 12 October 2026 were £35.10 a metre for a 178x102x19 beam and £46.20 for a 254x102x25. With cutting and delivery, a short domestic RSJ is typically £150 to £300 supplied. The whole job, with calcs, building control, fitting and making good, typically lands at £1,600 to £3,200.

How much is an RSJ for a 3 m opening?

For a 3m RSJ cost, the steel itself is typically £150–£300 supplied in 2026 for the small UC sections common at that span. The installed job, calcs, building control, fitting and making good, typically lands at £1,600–£3,200.

How much does a 5m RSJ cost?

At 5 m the steel is usually a 254x146 or 305x165 universal beam, unpriced by any stockist we read, so get a quote for your engineer's section. At the published £46.20 a metre, the lighter 254x102x25 is £231 for 5 m before cutting, delivery and VAT. Lifting kit often raises the installation line more than the steel.

Is there an RSJ cost calculator?

Three lines. The section our checker indicates, priced per metre from a stockist for the engineer's bearing length. The engineer's calcs. Installation and making good, from the table above. No calculator can price the steel before the section is calculated, which is why the calcs come first.

How much do structural engineer calculations cost for an RSJ?

Typically £250–£500 in 2026 for a single domestic beam, more with several beams, a site survey or revised drawings. It is the smallest line and the only one building control insists on. On 12 October 2026 Beam Dezign listed RSJ calculations from £75 plus VAT and Beam Designs £95. SBS Structures in London said single steel beams start at £400.

Sources

This site's own dataset, every figure quoted from its source and dated:

The UK Steel Beam Cost Index carries 7 published figures read from 7 sources' own pages; the 4 published figures given without a breakdown run from 75 to 1,200 GBP, read 11 November 2026.

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