C Purlins (Cees) C
AS 1397 / AS/NZS 4600Cold-formed, galvanised C sections used as purlins, girts, light beams and studs. Dimensions per Lysaght Zeds & Cees. Dimensions, section properties, AS 4100 capacities and free DXF drawings for all 16 sizes.
Cee (C) sections are roll-formed from galvanised high-strength strip (G450 for 1.5 mm and thicker, G500 for 1.2 mm and G550 for 1.0 mm). They are used as purlins and girts on simple spans, and as light beams, studs, lintels and frames. Cees can be butted but not lapped.
The designation gives the nominal depth and the base metal thickness (BMT) ×10: a C20019 is 203 mm deep and 1.9 mm thick. Dimensions here are those published by Lysaght for its Zeds & Cees range. Other manufacturers (e.g. Stramit) use similar but not identical sizes.
Select any section in the table to open its page, with a dimensioned drawing, all section properties and a free DXF download for your CAD software.
| Designation | Mass kg/m | D mm | B mm | L mm | t mm | Ag mm² | Ix 10⁶mm⁴ | Zx 10³mm³ | Sx 10³mm³ | Iy 10⁶mm⁴ | ry mm | J 10³mm⁴ |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C10010 | 1.78 | 102 | 51 | 12.5 | 1.0 | 216 | 0.364 | 7.13 | 8.18 | 0.0755 | 18.7 | 0.0719 |
| C10012 | 2.10 | 102 | 51 | 12.5 | 1.2 | 257 | 0.432 | 8.48 | 9.75 | 0.0892 | 18.6 | 0.124 |
| C10015 | 2.62 | 102 | 51 | 13.5 | 1.5 | 323 | 0.537 | 10.5 | 12.2 | 0.112 | 18.7 | 0.242 |
| C10019 | 3.29 | 102 | 51 | 14.5 | 1.9 | 409 | 0.673 | 13.2 | 15.3 | 0.142 | 18.7 | 0.492 |
| C15012 | 2.89 | 152 | 64 | 14.5 | 1.2 | 353 | 1.29 | 17.0 | 19.6 | 0.188 | 23.1 | 0.170 |
| C15015 | 3.59 | 152 | 64 | 15.5 | 1.5 | 443 | 1.61 | 21.1 | 24.5 | 0.237 | 23.1 | 0.332 |
| C15019 | 4.51 | 152 | 64 | 16.5 | 1.9 | 561 | 2.02 | 26.6 | 30.9 | 0.300 | 23.1 | 0.675 |
| C15024 | 5.70 | 152 | 64 | 18.5 | 2.4 | 712 | 2.54 | 33.5 | 39.1 | 0.386 | 23.3 | 1.37 |
| C20015 | 4.49 | 203 | 76 | 15.5 | 1.5 | 555 | 3.53 | 34.7 | 40.4 | 0.396 | 26.7 | 0.416 |
| C20019 | 5.74 | 203 | 76 | 19.0 | 1.9 | 713 | 4.51 | 44.4 | 51.8 | 0.531 | 27.3 | 0.858 |
| C20024 | 7.24 | 203 | 76 | 21 | 2.4 | 904 | 5.69 | 56.0 | 65.6 | 0.681 | 27.4 | 1.74 |
| C25019 | 6.50 | 254 | 76 | 18.5 | 1.9 | 808 | 7.62 | 60.0 | 71.0 | 0.561 | 26.4 | 0.972 |
| C25024 | 8.16 | 254 | 76 | 20.5 | 2.4 | 1024 | 9.62 | 75.7 | 89.9 | 0.721 | 26.5 | 1.97 |
| C30024 | 10.1 | 300 | 96 | 27.5 | 2.4 | 1264 | 17.0 | 113 | 133 | 1.51 | 34.6 | 2.43 |
| C30030 | 12.8 | 300 | 96 | 31.5 | 3.0 | 1596 | 21.3 | 142 | 168 | 1.96 | 35.0 | 4.79 |
| C35030 | 15.2 | 350 | 125 | 30 | 3.0 | 1911 | 35.8 | 205 | 239 | 3.82 | 44.7 | 5.73 |
Frequently asked questions
- Why are there no AS 4100 capacities for purlins?
- Thin cold-formed sections are designed to AS/NZS 4600, where local and distortional buckling, bridging and cladding restraint govern. Use the manufacturer's span and capacity tables.
- Can C sections be lapped?
- No. Cees are butted or spliced at supports. Use Zeds where you want lapped, continuous runs.
Relevant Australian Standards
- AS/NZS 4600:2018 Cold-formed steel structures
The design Standard for thin-walled cold-formed members such as C and Z purlins and light-gauge framing. - AS 1397:2021 Continuous hot-dip metallic coated steel sheet and strip
Covers the G450, G500 and G550 zinc-coated (Z350, Z450) and zinc/aluminium coated steel strip from which purlins, girts and light-gauge framing are roll-formed. - AS/NZS 1170 series Structural design actions
Defines dead, live (1170.1), wind (1170.2), snow (1170.3) and earthquake (AS 1170.4) actions and the load combinations (1170.0) that produce the design actions resisted by the capacities shown here.