C-section (steel)

A C-section is a cold-formed steel section shaped like a C (a lipped channel). It is the workhorse stud, joist, and plate profile in light-gauge steel framing, roll-formed from galvanised coil to AS/NZS 4600.

“Cold-formed” means the section is rolled to shape from thin galvanised steel coil at room temperature, not hot-rolled like a structural beam. The C shape, a web with two flanges and a small return lip on each flange, is efficient: the lips stiffen the flanges so a very thin section resists buckling and carries useful load for its weight. C-sections are used as wall studs, floor and ceiling joists, rafters, and (paired or with a track) as plates and bearers.

A few things matter with C-sections:

• Buckling, not yielding, usually governs: being thin, they fail by local or distortional buckling, so the design (to AS/NZS 4600) and the bracing/blocking are about stopping buckling, not just stress.
• The galvanising is the corrosion protection: cut ends and damage need treatment, and the coating class has to suit the exposure.
• Connections are screwed or riveted to the section, and pierce the steel, so fastener type, size, and pattern are part of the design.

For a builder the practical points are to handle and store C-sections so the thin flanges and lips do not get bent (a kinked lip compromises the section), to brace and block studs and joists as the design requires because their capacity depends on restraint against buckling, and to use the specified screws and protect cut edges. Do not notch or oversize-hole a C-section freehand: holes and their positions are part of the AS/NZS 4600 design, not site discretion.

Also known as: Lipped channel, C-stud, cee section.

Category: Steel framing / Sections.

Related

• Steel framing basics
• AS/NZS 4600 cold-formed steel

See also

• Snug-tight

References

• AS/NZS 4600 Cold-formed steel structures, Standards Australia (verified 2026-06-01)

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Last updated: 2026-06-01. Verified: 2026-06-01. Quarterly review for currency.