In metal roofing, PBR stands for "Purlin Bearing Rib" or "Purlin Bearing Profile." It is a type of metal panel that has a raised rib or seam that runs along the panel's length. The raised rib provides additional strength to the panel and allows it to span further distances without the need for additional supports. The PBR panel is commonly used in commercial and industrial metal roofing applications due to its durability, cost-effectiveness, and ease of installation.