The 152 x 152 UC23 universal column is the smallest section in the UC range and the one most commonly used in UK domestic work — the post that carries the end of an RSJ where a wall has been removed and there is nothing left to bear onto. At 152.4mm deep and 152.2mm wide it is very nearly square, which is exactly the point: a column has to resist buckling in every direction, not just one. Rolled to S355J0 and supplied cut free to any length from 1m to 12m in mill finish or red oxide primer, 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 a column is not just a short beam
A beam fails in bending; a column fails in buckling, and it buckles about whichever axis is weakest. That is why universal columns are close to square while universal beams are tall and narrow — see UB vs UC, what UK builders actually specify for the full explanation.
The numbers make it plain. A UC23 has a radius of gyration of 6.5cm about the major axis and 3.6cm about the minor — a ratio of 1.8. A 203 x 102 UB23 of almost identical weight has 8.4cm against 2.2cm, a ratio of nearly 4. Loaded axially over any real height, that beam would buckle sideways long before the column would.
What governs the design is effective length — the height between restraints, adjusted for how the ends are fixed. Double the effective length and the buckling capacity falls to roughly a quarter. This is why the same column can be perfectly adequate in a 2.4m domestic storey and badly undersized in a 4m open-plan space, and why the connection detail at head and base matters as much as the section itself.
Where the UC23 is typically used
Most commonly as a padstone-mounted post supporting one or both ends of a beam when removing a load-bearing wall, particularly where the opening runs to the corner of a room and there is no return wall to bear on. It also appears in garden rooms, mezzanine frames, car ports and porch structures. The UK steel beam size chart lists every UB, UC and PFC size with weights if you are still comparing.
Available finishes
Mill finish is the column exactly as it leaves the rolling mill: bare structural steel 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.
Red oxide primer is a factory-applied anti-corrosive coating that protects the steel while it sits on site or in an unheated shell before the building is closed in. Columns often go in early in a build programme and stand exposed for longer than beams do, which makes primer worth considering here. It is a primer, not a topcoat — designed to be overpainted, and not a substitute for intumescent fire protection or galvanising outdoors. More in what red oxide primer actually means.
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 2.4m requirement is charged as 3m; where you order more than one cut in the same finish, the total is rounded once rather than cut by cut, which keeps the cost down when you need a pair of posts.
Cut tolerance is ±3mm on length. Columns are usually cut to a tighter tolerance than beams in practice, so tell us if your head detail is critical and confirm the base plate and padstone arrangement with your engineer before ordering. More on what lengths structural steel comes in.
Section dimensions
| Depth of section (h) | 152.4 mm |
| Width of section (b) | 152.2 mm |
| Web thickness (s) | 5.8 mm |
| Flange thickness (t) | 6.8 mm |
| Root radius (r) | 8.0 mm |
| Depth between fillets (d) | 122.8 mm |
| Mass per metre | 23.0 kg/m |
| Cross-sectional area | 29.2 cm² |
| Surface area per metre | 0.888 m²/m |
Section properties
| Second moment of area, y-y (Iy) | 1,252 cm⁴ |
| Second moment of area, z-z (Iz) | 399.9 cm⁴ |
| Elastic modulus, y-y (Wel,y) | 164.3 cm³ |
| Elastic modulus, z-z (Wel,z) | 52.55 cm³ |
| Plastic modulus, y-y (Wpl,y) | 182.3 cm³ |
| Plastic modulus, z-z (Wpl,z) | 80.18 cm³ |
| Radius of gyration, y-y (iy) | 6.5 cm |
| Radius of gyration, z-z (iz) | 3.6 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
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. A 152 x 152 UC23 weighs 23kg per metre, so a 3m post is 69kg — usually a two-person lift. Deliveries are kerbside and offloading assistance is required.
See how structural steel is delivered for what to expect on the day, or our delivery & lead times page. Ordering columns and beams together for one project? Trade discounts are available.
Related sections
- 152 x 152 UC30 steel column — heavier section in the same serial size
- 152 x 152 UC37 steel column — heaviest in the same serial size
- 203 x 203 UC46 steel column — next size up for higher loads
- All universal columns (UC)
- All RSJ steel beams & columns