The 254 x 254 UC73 universal column is the lightest section in the 254 x 254 range and the largest column we stock cut-to-size. Stepping up from 203 x 203 to a full 254mm square transforms the column's stiffness about both axes, which is why it is reached for when the 203 range has run out of capacity or when a longer unrestrained height demands it. At 73.1kg per metre it carries a similar weight to a 203 x 203 UC71 but with markedly more buckling resistance. Rolled to S355J0 and supplied cut free to any length from 1m to 12m in mill finish, with free UK mainland delivery included in the price.
Steel grade — S355J0 to BS EN 10025-2
This column 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.
Why the jump to 254 x 254
The UC73 weighs about the same per metre as a 203 x 203 UC71, but because the steel is spread across a 254mm square rather than a 203mm one, its weak-axis radius of gyration rises from 5.2cm to 6.4cm. Since buckling capacity scales with the square of that figure against effective length, the UC73 is dramatically more capable over a tall storey — a 23% larger radius of gyration is roughly a 50% gain in slenderness terms.
That is the whole reason the 254 x 254 range exists: not to carry more weight, but to carry the same load over greater heights, or to resist buckling where a 203 section would be too slender. The trade-off is footprint — a 254mm square column is a visible structural element that will not hide inside a normal wall. See UB vs UC, what UK builders actually specify, and the UK steel beam size chart for every size with weights.
Where the UC73 is typically used
Tall ground-floor columns in multi-storey frames, long unrestrained posts in double-height spaces and industrial buildings, and main structural columns carrying transfer beams. It is always part of a fully engineered steel frame.
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. It suits any job where the column will be encased, boxed in, fire-protected or painted on site — see our guide to boxing in steelwork, or whether structural steel needs painting at all. Store it dry and ventilated, and protect it with a suitable coating system if it will be exposed or used externally.
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 cut lengths on one order and the tool works out what you need. Steel is supplied and billed in whole metres, so a 2.7m requirement is charged as 3m; where you order more than one cut, the total is rounded once rather than cut by cut.
Cut tolerance is ±3mm on length. Tell us if your head detail is critical, and confirm the base plate, padstone and holding-down bolt arrangement with your engineer before ordering. More on what lengths structural steel comes in.
Section dimensions
| Depth of section (h) | 254.1 mm |
| Width of section (b) | 254.6 mm |
| Web thickness (s) | 8.6 mm |
| Flange thickness (t) | 14.2 mm |
| Root radius (r) | 13.0 mm |
| Depth between fillets (d) | 200.3 mm |
| Mass per metre | 73.1 kg/m |
| Cross-sectional area | 93.1 cm² |
| Surface area per metre | 1.487 m²/m |
Section properties
| Second moment of area, y-y (Iy) | 11,410 cm⁴ |
| Second moment of area, z-z (Iz) | 3,907 cm⁴ |
| Elastic modulus, y-y (Wel,y) | 898.4 cm³ |
| Elastic modulus, z-z (Wel,z) | 306.9 cm³ |
| Plastic modulus, y-y (Wpl,y) | 992.7 cm³ |
| Plastic modulus, z-z (Wpl,z) | 465.4 cm³ |
| Radius of gyration, y-y (iy) | 11.0 cm |
| Radius of gyration, z-z (iz) | 6.4 cm |
Nominal dimensions and properties to BS EN 10365. Figures are published for reference only.
Structural engineer notice
Column sizing cannot be taken from a table. Capacity depends on the axial load, the effective length between restraints, the end fixity, any bending applied at the connections, and the base and head details — all of which must be calculated by a qualified structural engineer, and in most cases will form part of your building control submission. Base plates, padstones and holding-down bolts are part of that design. We supply steel to the specification you give us; we do not provide structural design.
Delivery — plan the lift
Cut-to-size steel is 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. At 73.1kg per metre a 3m post is 219kg and a 5m post is 366kg. Deliveries are kerbside and offloading assistance is required — a forklift or crane is essential at this weight. See how structural steel is delivered, or our delivery & lead times page. Ordering a full frame? Trade discounts are available.
Related sections
- 203 x 203 UC86 steel column — heaviest 203 section, smaller footprint
- 203 x 203 UC71 steel column — similar weight in a 203 footprint
- All universal columns (UC)
- All RSJ steel beams & columns