Abstract: This invention provides a panel assembly for buildings and the like comprising, in combination with structure supporting the assembly, an array of overlapping elongated metal panels, each panel including a lower edge, an upper flange, and a web including at least one outwardly protruding longitudinally extending stiffening rib. The stiffening rib adjacent the upper flange has an elongated longitudinally extending groove and an extended bearing portion for contacting the structure when the panel is fastened thereto. These ribs provide structural support without purlins, sheathing, or the like.