The 178 x 102 UB19 is an S355J0 structural steel universal beam (RSJ) weighing 19 kg per metre. Available in mill finish or red oxide primer, cut to your exact required length from 1m to 12m using our online cut-to-size calculator. Commonly specified for wider wall openings, rear extensions, loft conversions, floor and roof support and light commercial steelwork 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 178 x 102 UB19 refers to a nominal depth of 177.8mm, nominal flange width of 101.2mm and a linear mass of 19 kg/m. Full section properties are published under BS EN 10365:2017. See our steel grades and standards guide for more on S275 and S355.
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 painted or 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. Steel is supplied in whole metres, so we add up everything you need and round the total up to the next full metre — two 4.2m cuts use 8.4m of steel and are billed as 9m, not 10m. The cutting itself is free of charge. Multiple cuts and quantities can be added in a single order, and all cuts are to +/- 3mm tolerance. Maximum single length is 12m. Cut-to-length steel is made to your specification and is non-returnable unless faulty or supplied incorrectly.
Section Dimensions
Depth (h): 177.8mm | Width (b): 101.2mm | Web thickness (s): 4.8mm | Flange thickness (t): 7.9mm | Root radius (r): 7.6mm | Depth between fillets (d): 146.8mm | Mass: 19.0 kg/m
Section Properties (to BS EN 10365)
Published section properties for the 178 x 102 x 19 UB. Figures are nominal and for reference only — your structural engineer will confirm the values used in design.
| Property | Axis y-y (major) | Axis z-z (minor) |
|---|---|---|
| Second moment of area, I | 1356 cm4 | 137 cm4 |
| Radius of gyration, i | 7.47 cm | 2.37 cm |
| Elastic section modulus, Wel | 153 cm3 | 27.1 cm3 |
| Plastic section modulus, Wpl | 171 cm3 | 41.6 cm3 |
Cross-sectional area: 24.3 cm2 | Torsion constant, IT: 4.41 cm4 | Mass: 19.0 kg/m
Structural Engineer Notice
The 178 x 102 UB19 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. 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. See how our RSJ steel beams are delivered for full details.
Related Sections
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