Smith Built’s R-Panel metal roofing and metal siding system is a strong, durable, energy-efficient choice for both roofing and siding applications. R-Panel, sometimes referred to as PBR (Purlin Bearing Rib) Panel, is formed with sturdy 1 ¼” trapezoidal ribs which are spaced on 12” centers. R-Panel has strength and water tightness characteristics that make this panel perfect for a variety of applications.