Metal Panel Roof Systems For Low-Slope Applications
There’s just one type of metal roof systems used in low-slope applications — structural metal panel. Structural metal panel roof systems can be used for low slope roofs due to their hydrostatic, features, or water obstacle. It is necessary to notice structural metal panel roof systems can be used for steep slope roof assemblies, also. Most structural metal panel roof systems are made to resist the passing of water at other joints and laps, as sealant or anti capillary layouts can be used in the seams. Strength features that enable them to whirl supporting members are possessed by structural metal panel roof systems. Structural metal panel roof systems are installed over a big variety of substrates. There are two general types of substrates: one is constant or closely spaced decking that provides strong support for the metal roof panel, and the other consists of spaced structural supports (including purlins) where the metal panels must span between supports. Without being supported by a solid roof deck structural metal panels are used over spaced structural supports.
Underlayment is installed over the roof deck before the use of a metal panel roof system. An underlayment performs primary functions: it provides temporary weather protection and a secondary weather proofing obstacle, respectively if moisture infiltrates the metal roof panels.
If an underlayment will be installed, NRCA recommends a minimum of one layer of No. 30 asphalt-saturated felt used horizontally in shingle style on roof decks having a slope of 4:12 (18 degrees) or more. For roof decks having slopes of 3:12 (14 degrees) up to 4:12 (18 degrees), a minimum of two layers of No. 30 asphalt-saturated underlayment should be used horizontally in shingle style. NRCA also advocates a slip sheet be installed over the underlayment for metal panel roof systems. A slip sheet is a layer of building paper that is smooth, like rosin- sized or building paper that is unsaturated. Its goal would be to shield the underlayment from damage, as the panels split the underlayment and can stick to.
- NRCA does urge that metal roof systems meet standards.
- STM E1514, “Standard Specification for Structural Standing Seam Steel Roof Panel Systems”
- ASTM E1637, “Standard Specification for Structural Standing Seam Aluminum Roof Panel Systems”