a. Z-type purlins are more integral than C-type purlins because the inertia moment in the weak axis direction is larger than that of similar C-type purlins. C-type steel machines are generally suitable for roofs with gentle slopes; while Z-type steels are suitable for slopes greater than 1 /4 of the roof.
b. Because the joint should be firmly lapped, it will become a continuous purlin after the lap, and the C-type purlin can only be calculated as a simply supported purlin.
c. Z-type purlins are smaller than C-type purlins, which can save materials and reduce construction costs. However, installation and transportation are more complicated than C-type purlins.