Abstract: A standing rib roof structure made up of a plurality of panels joined along adjacent edges, the adjacent edges each being formed as half a standing rib so that the seam between each adjacent pair of panels becomes a standing rib, each edge having a locking means thereon, one edge having a female locking member and the opposite edge having a male locking member that is lockable to the female locking member by being received therein, and a panel clip for fixing the panels to a building, the panel clip being receivable between the male locking member and the female locking member, and having a base for securing the clip to the building.