'Z' AND 'C' SECTION (PURLIN)
A traditional purlin strictly by definition is a horizontal structural member in a roof. Purlins traditionally support the roof deck / cladding / sheeting and are in turn supported by the principal rafters / steel beams etc.
In the past, the majority of roof structures were of wooden construction but over the past 15 to 20 years there has been a vast shift away from wood to metal (mainly steel) roof construction. The typical roof structure now consists of steel “I” beam rafters placed approximately 10 feet (this varies depending on purlin size and other variables) apart with either 4″, 6″, or 8″ lightweight steel purlins installed horizontally across the rafters. In some instances, either 6″ or 8″ “C” purlins back to back can be used as rafters. This is known as a lightweight steel system.
