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I (home owner) plan on a metal roof on a new house 60 miles southeast of Austin, Texas. Articles that I have read and contractors in the Austin area suggest varied and seemingly mutually exclusive approaches. For example, no sheathing, with roofing applied directly onto 2 by 4s run across the rafters; Kool*Ply (or other sheathing), with metal roofing directly on top of Kool*Ply; or Kool*Ply, with 2 by 4s on top, then roofing directly on top of 2 by 4s. I am looking for guidance based more on technical and climatic, rather than cost, considerations.
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There is no "one way" to do the roof structure so can't help you there. But, I can tell you how to find out what the roofing manufacturer recommends, and will accept if warranty time comes: Read the installation instructions.
You can install metal roofs with a variety of sheathing products and with skip sheathing. But all must comply with the manfacturer's instructions for satisfactory performance.
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*I'm not an expert on metal roofing but we installed Fabral 1-1/2" standing seam steel roofing on our hunting camp last year. The original galvanized metal roofing had been on there for about 60 years but we were getting too old to paint it every 3 years so we tore it off,renailed and replaced any bad 1" sheathing,applied 55# smooth roll roofing felt,and then the steel roof.The space below the roof is vented. I think you need something to act like a vapor barrier to prevent condensation on the bottom of the metal roofing. The original metal roof had some areas where there was rust on the bottom.
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I (home owner) plan on a metal roof on a new house 60 miles southeast of Austin, Texas. Articles that I have read and contractors in the Austin area suggest varied and seemingly mutually exclusive approaches. For example, no sheathing, with roofing applied directly onto 2 by 4s run across the rafters; Kool*Ply (or other sheathing), with metal roofing directly on top of Kool*Ply; or Kool*Ply, with 2 by 4s on top, then roofing directly on top of 2 by 4s. I am looking for guidance based more on technical and climatic, rather than cost, considerations.
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