Compared with C Purlins, Z Purlins have the following advantages:
1. Convenient transportation, more Z Purlins are transported in the same volume, which reduces the transportation cost of purlins per unit;
2. Better mechanical performance;
3. Continuous purlins can be made to reduce the height of purlins section and save material.
The second problem is to use C Purlins and Z Purlins in addition to the eaves. The difference is not big, but there are not many manufacturers that can process Z purlin at present. In the design, the purchasing problem of the construction party should also be considered. The third problem is that if the purlin is simply supported, the cross sections of the two purlins are not very different. C-purlin can not be used as continuous purlin.
