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Guest User
7/16/2008
I currently have a shingled roof with poor ventilation. I have measured the underside of my roof at 160 degrees and attic space at 140 degrees. From my research I plan on doing the following. NOTE: The roof is a 1950 single story hip roof with 1 valley, 4x12 pitch. Average 8in/yr rain, and 0in of snow. 1. Removing all old roofing to the 1x6 T&G decking. 2. Add Eave vents (1 or 2 inch) in decking to allow air between decking and metal roof. 3. Put underpayment on top of existing deck. 4. 1x4 ran vertically from eave to ridge. To allow for natural convection from eave to ridge. 5. 1x4 Purlin (horizontal). To support Standing Seam panels. 6. 16" Standing seam panels with ridge cap vents on all ridges. "Colonial Red" in color. My questions. Q1. To better prevent heat build up in the Attic during the summer months, where should I put a radiant barrier: Directly over the underpayment with bubble insulation and radiant barrier up? Between the 1x4's with a bubble separated double sided radiant barrier? Just below the Standing Seam metal roof with radiant barrier down? Q2. Should I expect any moisture build up with a metal roof vented this way? Q3. If I follow the Manufacturers instructions on spacing the Purlins, will I have any problems with walking on the completed roof? Q4. Are there any reports on the performance of a Standing Seam roof with and without a radiant barrier installed? Q5. Can I over ventilate this installation and cause noise in high wind? Q6. Any suggestions to make it easier/better?
Todd Miller
Isaiah Industries, Inc.
7/20/2008
To be effective the radiant barrier must face an airspace, not be in a tight sandwich. I would suggest working with your standing seam mfr to determine exact details. The ventilation should avoid moisture build up. Can you though ventilate the actual attic? I am not familiar with any reports with and without radiant barrier. Ventilation should not increase noise provided the roof is properly installed.
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