ARE Exam Prep: Purlin for PPD & PDD | ARE Lab

A comprehensive look at purlins, which are horizontal, secondary structural members that support the roof deck and transfer loads to the primary structural system, such as rafters or trusses. The first source, excerpts discussing the material in the context of the ARE 5.0 architectural exams, emphasizes the distinction between purlins (roof members) and girts (wall members), details various design considerations like wind uplift and lateral bracing (bridging), and outlines how these concepts are tested in the PPD and PDD sections. The second source, a YouTube transcript from a civil engineering channel, focuses on the structural role of purlins, distinguishing between C-purlins (versatile and common) and Z-purlins (stronger, often overlapped for continuity), and explains how purlins ensure stability by evenly distributing the roof load. Both sources agree that purlins are critical for structural integrity, with the architectural source focusing on design details and coordination while the engineering source explains their material and load-bearing function.