R-Panel features an optional purlin bearing leg (PBR) that rests on purlins and provides support for fastening the panel lap. This makes R-Panel a strong and durable panel that is well-suited for use in high-wind and hail-prone areas. Typically, PBR panels are utilized on roof applications because roofers appreciate the extra support when installing the panels to the roof substrate, or deck. R-Panels without the PB leg (purlin bearing) are more common for wall applications.