The standing seam raises the longitudinal joint above the plane of water runoff. This is one of the reasons for using such a covering. However, it does not make the roof watertight regardless of how it is installed. Water must have a correct path from the ridge to the gutter. Equally important are the panel ends, the flashings and the ability of the metal sheet to move thermally. The visible strip is a thin metal sheet with appropriately formed edges. On the roof it may be flat or have small pressings. Adjacent strips are joined by traditional folding or a snap lock. From the outside both solutions create a longitudinal rhythm, but they have a different construction.