Dual-arch roof tile

A tile for attachment to a mounting surface, with a fastener, includes a body defining a longitudinal length and a horizontal width. The body may be movable between an uninstalled position, which defines a first offset along the longitudinal length and a second offset along the transverse width, and an installed position, which substantially closes the first offset and the second offset. In the installed position, the body abuts the mounting surface and an underside of the body is substantially planar. The tile may also include a plurality of first-angle ribs and a plurality of second-angle ribs. The first-angle ribs are offset relative to a forward edge of the body. The second-angle ribs offset relative to the forward edge of the body and also to the first-angle ribs. Furthermore, the first-angle ribs and second-angle ribs do not have shared vertices.