Steel channel purlin is usually made of Studs Tracks and channel forming machine that is thin enough to put screws through. Cold-formed steel is made by channel forming machine. It is less expensive for the manufacturer than hot-rolled steel and is also easier to work with. Though cold-formed steel is stronger than hot-formed steel, it is more likely to break when under pressure rather than bend.

Purlins are manufactured from hot dipped galvanized steel with a coating, in line with other common lightweight steel structural building products. This gives good protection in most exposed internal environments. Run off from, or contact with, materials which are incompatible with zinc should be avoided.

To protect the purlin, they also apply a layer of paint outside them. Zinc and paint in combination (synergistic effect) produce a corrosion protection approximately 2X the sum of the corrosion protection that each alone would provide.