Interlock Roofing® Standing Seam Roof is a fully interlocking system. Its unique design profile makes a weather-tight unit, and, unlike some other metal roofs, no rivets or screws are exposed on the surface of the panels. It may be installed on new construction, or applied over existing roofs. All trims and caps are designed to ensure an integrated weather-proof roof. Standing Seam has many advantages over antiquated, notoriously inefficient tar and gravel roofs.