A standing seam roof is constructed of many interlocking panels that run vertically from the roof's ridge (the top of the roof) to the eave. The interlocking seam where two panels join together is raised above the roof's flat surface, allowing water to run off without seeping between panels.
Standing seam roofs come in many shapes and sizes. In some instances, the vertical panels are cut to length at a factory and delivered to the job site. Other types are shaped and cut right on the job site using portable equipment. Other options include standing seam "shingles" that arrive prepackaged (typically in three- to five-foot lengths) and are installed in a staggered pattern for visual effect.
Two types of methods are commonly used to secure the panels to the roof sheathing. Hidden fasteners are secured to the raised portion of each panel, and subsequently covered by the next adjoining panel during installation. The second (and less costly) method utilizes exposed fasteners that are driven through each metal panel into the roof sheathing
Steel shingle or standing-seam roofs last about 50 years or more depending on both the method of installation and the moisture barrier (underlayment) used and are between the cost of shingle roofs and slate roofs.