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SHS 150×150×5 vs CF SHS 150×150×5

SHS 150×150×5 is an SHS Hot-finished section from the UK Blue Book (SCI P363); CF SHS 150×150×5 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 156 cm³ against 153 cm³ of plastic modulus, a difference of 2.0%. They weigh essentially the same, 22.6 kg/m and 22.3 kg/m. Both are about 150 mm deep, so either fits the same construction zone.

Section properties side by side. Bold marks the more favourable value where one is.
PropertySHS 150×150×5
SHS Hot-finished
CF SHS 150×150×5
SHS Cold-formed
Difference
Mass22.6 kg/m22.3 kg/m+1.3%
Depth150 mm150 mmsame
Width150 mm150 mmsame
Web thickness0 mm0 mmsame
Flange thickness0 mm0 mmsame
Area28.7 cm²28.4 cm²+1.1%
Second moment, major (Iy)1,000 cm⁴982 cm⁴+1.8%
Plastic modulus, major (Wpl,y)156 cm³153 cm³+2.0%
Elastic modulus, major (Wel,y)134 cm³131 cm³+2.3%
Second moment, minor (Iz)1,000 cm⁴982 cm⁴+1.8%
Plastic modulus, minor (Wpl,z)156 cm³153 cm³+2.0%
Radius of gyration, minor (iz)5.9 cm5.89 cm+0.2%
Torsion constant (It)1,550 cm⁴1,550 cm⁴same

SHS 150×150×5 to BS EN 10210-2:2006; CF SHS 150×150×5 to BS EN 10219-2:2006. Difference is expressed relative to CF SHS 150×150×5.

How to choose between them

On stiffness, SHS 150×150×5 has the larger second moment of area: 1,000 cm⁴ against 982 cm⁴, a difference of 1.8%. 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 (6.9 against 6.9 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, these two are genuine equivalents. Pick whichever your supplier stocks and the rest of the frame already uses.

Common questions

They are effectively equal in bending. SHS 150×150×5 has a plastic modulus of 156 cm³ and CF SHS 150×150×5 has 153 cm³, a difference of only 2.0% - within the margin that section choice normally turns on. Compare stiffness and availability instead.

Neither meaningfully: SHS 150×150×5 is 22.6 kg/m and CF SHS 150×150×5 is 22.3 kg/m. On a tonnage basis they cost the same.

Structurally it is the closest equivalent we hold: CF SHS 150×150×5 gives 153 cm³ of plastic modulus and 982 cm⁴ of inertia against 156 cm³ and 1,000 cm⁴. Re-check deflection and the connection details before swapping, since the flange and web thicknesses differ.

SHS 150×150×5, with a second moment of area of 1,000 cm⁴ against 982 cm⁴ (1.8% more). Deflection under a uniform load goes as 5wL⁴/384EI, so it is inversely proportional to I - on a span where the deflection limit governs rather than strength, this is the number that decides the section.

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