SHS 100×100×4 vs CF SHS 100×100×4
SHS 100×100×4 is an SHS Hot-finished section from the UK Blue Book (SCI P363); CF SHS 100×100×4 is the closest equivalent in the UK Blue Book (SCI P363). SHS 100×100×4 carries more bending: 54.4 cm³ of plastic modulus against 53.3 cm³, 2.1% more. They weigh essentially the same, 11.9 kg/m and 11.7 kg/m. Both are about 100 mm deep, so either fits the same construction zone.
| Property | SHS 100×100×4 SHS Hot-finished | CF SHS 100×100×4 SHS Cold-formed | Difference |
|---|---|---|---|
| Mass | 11.9 kg/m | 11.7 kg/m | +1.7% |
| Depth | 100 mm | 100 mm | same |
| Width | 100 mm | 100 mm | same |
| Web thickness | 0 mm | 0 mm | same |
| Flange thickness | 0 mm | 0 mm | same |
| Area | 15.2 cm² | 14.9 cm² | +2.0% |
| Second moment, major (Iy) | 232 cm⁴ | 226 cm⁴ | +2.7% |
| Plastic modulus, major (Wpl,y) | 54.4 cm³ | 53.3 cm³ | +2.1% |
| Elastic modulus, major (Wel,y) | 46.4 cm³ | 45.3 cm³ | +2.4% |
| Second moment, minor (Iz) | 232 cm⁴ | 226 cm⁴ | +2.7% |
| Plastic modulus, minor (Wpl,z) | 54.4 cm³ | 53.3 cm³ | +2.1% |
| Radius of gyration, minor (iz) | 3.91 cm | 3.89 cm | +0.5% |
| Torsion constant (It) | 361 cm⁴ | 362 cm⁴ | -0.3% |
SHS 100×100×4 to BS EN 10210-2:2006; CF SHS 100×100×4 to BS EN 10219-2:2006. Difference is expressed relative to CF SHS 100×100×4.
How to choose between them
On stiffness, SHS 100×100×4 has the larger second moment of area: 232 cm⁴ against 226 cm⁴, a difference of 2.7%. This matters more often than the strength comparison, because on normal floor spans deflection rather than bending capacity sets the beam size - so if the two are close on modulus but apart on inertia, the stiffer one is usually the better answer even when it is not the stronger one.
Measured as bending capacity per kilogram, the two are equally efficient (4.6 against 4.6 cm³ per kg/m), so on a pure steel-tonnage basis there is nothing to choose between them. The decision comes down to availability, connection detailing and what the rest of the frame uses.
In short, SHS 100×100×4 is the stronger section and CF SHS 100×100×4 is the lighter one; where those are the same section, it is the clear choice, and where they are not, decide on whether your design is governed by capacity or by tonnage.