Metal panels are generally not considered options for low slope roofs. Some metal panel systems, however, are often used on very low slopes. Although some manufacturers tout their systems as suitable for slopes as low as 1/4: 12 (2 percent), the NRCA recommends a minimum slope of 1/2 inch per foot as the minimum design slope for joints of hydrostatic roofing and three inches per foot because the design minimum slope for hydrokinetic systems. This section covers metal panels that can be used on slopes of 3:12 (25%) and less. These panels can also be used on slopes greater than 3:12. When installed on shallow slopes (especially slopes approaching 1/2: 12 (4 percent) or less), a metal panel system should provide water resistance over the entire roof area. Thus, low slope metal panel systems should be designed and installed with the intention of creating them as membranes. To achieve this, the joints of the panels must be welded or sealed along the side sealing tape or putty, or both. In addition, fasteners that penetrate the panel at end joints or flashings must be sealed with gasket washers. In activity to making all metal joints watertight, they must remain tight while undergoing significant thermal cycle movement. Over time, thermal movement of metal can tear fastener joints and enlarge holes in fasteners. Care should be taken to use a continuous sheet in a flat roof situation. The sheet is sensitive to wider and greater heat fluctuations due to its dense nature as a fabric,
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