Purlins and girts are roll formed Z sections, 200 mm deep with 64 mm flanges shall have a 16 mm stiffening lip formed at 45˚ to the flange. They are supported on columns, rafters or building walls. They can be lapped and nested at the supports which creates a continuous beam configuration. They are placed on the roof and perimeter of the building. Hence they serve as a support to the roof sheeting and wall cladding.