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standing seam metal roof consists of a system of panels locked together at raised seams or seamed mechanically. It is also known as a concealed fastener roof because the fasteners are hidden beneath the metal panels. This contrasts with exposed fastener roof systems where corrugated metal plates are fastened directly to the roof deck or framing with screws and gaskets that remain visible after installation. Besides aesthetics (some people consider exposed fasteners unsightly), one of the main advantages of standing seam metal roofs over exposed fastener systems is that the former give room for the
metal plates to glide during thermal expansion.
Changes in temperature cause metal to expand or contract (in hot and cold conditions, respectively). This is known as thermal expansion. Because exposed fastener roofs rely on screws and gaskets subject to the thermal expansion of the system (as well as to the wear and tear from the elements and UV radiation), the plate's perforations tend to wallow and the gaskets degrade over time. This puts the integrity of the roof structure at risk because of the potential for leaks or tears during inclement weather. For this reason, exposed fastener roof systems are recommended for industrial, structural, agricultural, and nonliving residential applications (e.g., porches, garages, and carports). Standing seam metal plates solve these issues by using cleverly engineered profiles and locking mechanisms that allow the plates to adjust for thermal expansion and eliminate the need for screws and perforations. Consequently, concealed fastener systems are the
metal roofing material recommended for residential structures.