254 x 146 UB31 S355J0 Steel Beam RSJ – Cut to Size

Not sure what size you need? View our RSJ Beam Size Guide — span guidance, section comparisons and planning advice for all standard UK sections.

The 254 x 146 UB31 is an S355J0 structural steel universal beam weighing 31 kg per metre. Available in mill finish or red oxide primer, cut to your exact required length from 1m to 10m using our online cut-to-size calculator. Commonly specified for building openings, mezzanine floors, structural steel frames, commercial and light industrial steelwork and secondary beam supports where this section has been confirmed by a structural engineer.

Steel Grade and Specification

Supplied in S355J0 structural steel conforming to BS EN 10025-2, with a minimum yield strength of 355 MPa. The section designation 254 x 146 UB31 refers to a nominal depth of 251.5mm, nominal flange width of 146.1mm and a linear mass of 31 kg/m. Full section properties are published under BS EN 10365:2017.

Available Finishes

Mill finish is supplied as-rolled with natural mill scale — the standard untreated surface straight from manufacture. Suitable for internal structural use where a protective coating will be applied on site.

Red oxide primer provides a shop-applied primer coat offering temporary corrosion protection during transport, storage and installation. Both finishes are structurally identical — the choice depends on your project specification and site requirements.

Cut to Size

Use our cut-to-size calculator above to enter your exact required length in mm. You are charged for the next 100mm increment — for example, 4165mm is billed as 4.2m. Multiple cuts and quantities can be added in a single order. All cuts are +/- 3mm tolerance. Cut-to-length steel is non-returnable unless faulty.

Section Dimensions

Depth (D): 251.5mm  |  Width (B): 146.1mm  |  Web thickness (S): 6.1mm  |  Flange thickness (T): 8.6mm  |  Root radius (R): 7.6mm  |  Depth between fillets (F): 219mm  |  Weight: 31 kg/m

Structural Engineer Notice

The 254 x 146 UB31 must be specified by a qualified structural engineer before ordering. Rackerman does not provide structural design advice and cannot confirm suitability for any specific opening, span or load condition. Building regulations approval is required for all structural alterations.

Delivery Information

Lead times are currently 5–10 working days — early bookings get priority. Delivery is kerbside only — our vehicles do not carry HIAB or lifting equipment. Suitable offloading labour or equipment must be arranged on site. Some postcode exclusions apply.

Frequently Asked Questions

What does RSJ stand for?
RSJ stands for Rolled Steel Joist. It is a general term used to describe structural steel beams — technically Universal Beams (UBs) — that are hot-rolled into an I-shaped cross section. RSJ, steel beam, I-beam, steel joist and universal beam all refer to the same type of section. The correct modern designation is Universal Beam (UB) with properties defined under BS EN 10365.

What sizes do RSJ steel beams come in?
Our RSJ beams range from 127 x 76 UB13 up to 254 x 146 UB37, covering the most commonly specified structural steel beam sizes for domestic and light commercial work. Each section is designated by its nominal depth x flange width and weight per metre. Beams are supplied cut to your required length from 1m to 10m.

How much does a steel beam weigh?
Steel beam weight depends on the section size and length. The weight per metre is part of the section designation — for example, a UB13 weighs 13 kg per metre, a UB25 weighs 25 kg per metre. Multiply the weight per metre by the length to get the total beam weight. Our product pages show the weight per metre for each section.

What is the difference between a Universal Beam and a Universal Column?
A Universal Beam (UB) has a deeper, narrower profile optimised for spanning horizontal loads — floor openings, lintels, roof beams. A Universal Column (UC) has a squarer, wider profile where the flange width is roughly equal to the depth, optimised for carrying vertical compression loads — posts, columns, vertical supports. Both are I-shaped steel sections in S355J0 grade to BS EN 10025-2.

Can RSJ beams be cut to size?
Yes. All our steel beams and columns are supplied cut to your exact required length using the cut-to-size calculator on each product page. Enter your length in mm and the price adjusts automatically. Cuts are +/- 3mm tolerance. Beams are delivered on a flatbed lorry within 5-10 working days.