The 254 x 102 UB28 steel beam is the heaviest section in the 254 x 102 serial size — 260.4mm deep at 28.3kg per metre, with a 10mm flange that gives it noticeably more capacity than the UB22 and UB25 below it. It is the section most often reached for when a 254 x 102 UB25 has been checked and come up short, but a move to the wider 254 x 146 range isn't wanted. Rolled to S355J0 and supplied cut free to any length from 1m to 12m, with free UK mainland delivery included in the price.
Steel grade — S355J0 to BS EN 10025-2
This beam is rolled in S355J0: a 355 N/mm² minimum yield structural steel with impact toughness certified at 0°C. S355 is the grade UK structural engineers design to by default, carrying roughly 29% more yield strength than the older S275 material some merchants still stock. If your engineer has calculated to S275, an S355 section of the same size will always satisfy that design — but never substitute in the opposite direction without going back to them first.
For a fuller comparison see our guide to S275 vs S355 steel, or the steel grades & standards reference for the full specification we supply against.
Where the UB28 sits in the 254 x 102 range
All three 254 x 102 sections share the same 224.4mm depth between fillets, so they detail almost identically — the difference is in the flange. The UB28's 10mm flange against the UB25's 8.4mm lifts the major-axis second moment of area from 3,421 cm⁴ to 4,012 cm⁴, roughly 17% more stiffness for 3.1kg per metre more weight. Where deflection rather than bending strength is governing, that is usually the cheaper way to solve the problem than stepping up a serial size.
The 102.2mm flange remains narrow relative to the 260.4mm depth, so lateral-torsional buckling still governs on longer unrestrained spans. Your engineer will account for restraint to the compression flange.
This size is common on wider load-bearing wall removals. The UK steel beam size chart lists every UB, UC and PFC size with weights if you are still comparing.
Mill finish
This section is supplied in mill finish — bare structural steel exactly as it leaves the rolling mill, carrying the usual blue-grey mill scale, handling marks and light surface oxidation that are normal for untreated steel. This is the correct specification where the beam will be encased in plasterboard, boxed in, fire-protected, or painted on site by your own decorator — see our guide to boxing in a steel beam, or whether RSJs need painting at all.
Store it dry and ventilated before installation. If the beam will be exposed, visible or used externally, it should be cleaned, prepared and protected with a suitable coating, galvanising or fire-protection system as required by the project specification.
Cut to size — free, to the millimetre
Tell us the length you need and we cut it. There is no charge for cutting and no minimum order beyond a single metre. Enter your dimensions in the calculator above — you can specify several different cut lengths on one order and the tool works out what you need. Steel is supplied and billed in whole metres, so a 4.2m requirement is charged as 5m; where you order more than one cut, the total is rounded once rather than cut by cut, which keeps the cost down on multi-beam jobs.
Cut tolerance is ±3mm on length. If your opening is tight, allow the usual bearing at each end and confirm the padstone detail with your engineer before ordering. More on what lengths RSJ beams come in.
Section dimensions
| Depth of section (h) | 260.4 mm |
| Width of section (b) | 102.2 mm |
| Web thickness (s) | 6.3 mm |
| Flange thickness (t) | 10.0 mm |
| Root radius (r) | 8.0 mm |
| Depth between fillets (d) | 224.4 mm |
| Mass per metre | 28.3 kg/m |
| Cross-sectional area | 36.1 cm² |
| Surface area per metre | 0.903 m²/m |
Section properties
| Second moment of area, y-y (Iy) | 4,012 cm⁴ |
| Second moment of area, z-z (Iz) | 178.5 cm⁴ |
| Elastic modulus, y-y (Wel,y) | 308.1 cm³ |
| Elastic modulus, z-z (Wel,z) | 34.94 cm³ |
| Plastic modulus, y-y (Wpl,y) | 353.4 cm³ |
| Plastic modulus, z-z (Wpl,z) | 54.88 cm³ |
| Radius of gyration, y-y (iy) | 10.5 cm |
| Radius of gyration, z-z (iz) | 2.2 cm |
Nominal dimensions and properties to BS EN 10365. Figures are published for reference only.
Structural engineer notice
Beam sizing is not something to work out from a table. The correct section for your opening depends on span, the loads carried above, bearing conditions, lateral restraint and the padstone detail — all of which must be calculated by a qualified structural engineer, and in most cases will form part of your building control submission. We supply steel to the specification you give us; we do not provide structural design.
Delivery
Cut-to-size beams are dispatched on a 5–10 working day lead time, with free delivery to UK mainland addresses included in the price — no carriage is added at checkout. A 254 x 102 UB28 weighs 28.3kg per metre, so a 5m beam is 142kg. Deliveries are kerbside and offloading assistance is required — our vehicles do not carry lifting equipment, so please have suitable labour or plant available.
See how RSJ steel beams are delivered for what to expect on the day, or our delivery & lead times page. Ordering several beams for one project? Trade discounts are available.
Related sections
- 254 x 102 UB25 steel beam — lighter section in the same serial size
- 254 x 102 UB22 steel beam — lightest in the same serial size
- 254 x 146 UB31 steel beam — wider flange for improved lateral stability
- All RSJ steel beams & columns
- Universal beams (UB)