Gauge and purpose. Structural studs are heavier gauge, engineered to carry vertical load, wind and racking forces, and are specified from load tables by depth, thickness and steel grade. Partition sections are light gauge and support only themselves and the boards fixed to them. They look similar on a rack and substituting one for the other is a recurring and potentially serious error.

Because their capacity is usually limited by local buckling of the thin flat elements rather than by the strength of the steel itself. Buckling resistance falls sharply as thickness reduces, so a small reduction in gauge produces a disproportionate loss of capacity. That is why cold-formed sections must be selected against manufacturers' tested load tables rather than by comparing nominal steel grades.

Not without checking. Pre-punched holes are positioned and sized so that their effect on capacity is accounted for in the published load tables. Cutting new holes, enlarging existing ones or notching flanges removes capacity in ways the design did not allow for, and in load-bearing framing that is a structural alteration. Where additional penetrations are needed, they require the designer's agreement.

As load-bearing walls, floors and roofs in low and medium-rise buildings, as infill walling within a concrete or steel frame, and as prefabricated panels assembled off site and craned into place. The low weight reduces foundation loads and makes handling easy, and the dimensional accuracy of roll-formed sections suits factory panelisation and rapid site assembly.

A coating weight matched to the service environment and design life, specified as a mass per unit area. Sections used in dry internal conditions need less than those exposed to humidity, condensation risk or external conditions during construction. Cut ends and drilled holes expose bare steel, which is generally tolerated because of the sacrificial protection zinc provides, but the base coating specification should still suit the exposure.