J. Holcomb
1/17/2016
Hello - I have a real issue with a building roof involving 5V metal over SIPS: extreme expansion/movement causes SIPS to rise and fall. It's a 10-yr-old roof (approx. 50'x100'), in full southern-exposure sun. Construction is 8'x16' SIPS, 8" thick, spanning 16'. On top of that are 2 layers of 30# felt, and polypropylene laminate roof underlayment. Roofing is 5V galvanized, screwed in the flats. We are measuring at least 1/4" rise in the center of the SIPS during mid-day sun. The metal roof appears to be pulling the SIPS up. This daily rise and fall is causing enormous noise in the post-and-beam construction, and the fear is that it may also be causing permanent structural damage. SIPS manufacturer has acknowledged their specs for spanning were inaccurate (panels are overspan). Question: what might be the best approach for minimizing the expansion/rise of the metal in this situation? Addition of venting? Re-roofing with screws through the ridges? Any advice will be greatly appreciated.
Eric Novotny
An informed customer is the Best Customer!
1/18/2016
Some more above deck venting might do the trick. Between that and attaching the metal to the pulins, that should keep the SIPS more isolated from the metal.

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