A singly symmetrical (C section) or a point-symmetrical (Z section) cold-formed purlin is even more susceptible to buckling because it has its shear center in a location quite different from the point ...

Cold-formed C and Z purlins are the ... and deflection criteria. Purlin spacing is dictated by the load-carrying capacity of the roof panels; a 5-ft spacing is common. Appendix B includes section ...