Light-gage purlins of 8 to 12 in in depth can span 25 to 30 ft, and even more, depending on the loading, material thickness, and deflection criteria. Purlin spacing is dictated by the load-carrying ...

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 ...