Since the moment of inertia on Z purlin’s weak axis is much bigger than that of C purlin, Z purlin works much better from the integrity point of view.
Z steel purlins can be overlapped continuously while C steel purlins cannot, therefore, it’s better to use Z steel purlins instead of c purlins on metal buildings with continuous spans.
Z purlins are much stronger than C purlins due to its continuous or overlapping capability. In this case, for the metal building with bigger roofing loading capacity.
On the roofing of steel framed structures with single spans, and for supporting walls, it’s better to use Cee purlins because it’s easy to install and calculate. On wa the can work as supporting for roof, walls and floor etc.
For the metal buildings installed with concealed fixing or klip lok roof panels, Z purlins can work better than C purlins.
