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I have from bottom to top - acoustical galvanized coil coated decking, plastic covered insulation in the low points, 5/8" treated plywood screwed down with SS screws, rubber membrane flashing, standing seam metal roof.
I am getting white rust from the acoustical holes on hot muggy days.
Why?
11/1/2021
Or copy this URL: https://www.metalroofing.com/spirit/comment/25733/find/This sounds like condensation which is the result of warm moist air originating inside the building trying to drive its way out and encountering a cooler surface along the way.
Isaiah Industries, Inc.
11/2/2021
Or copy this URL: https://www.metalroofing.com/spirit/comment/25737/find/It is an outside pavilion. And I was told there should be no white rust. Just trying to figure out where the mistake in design may be.
11/2/2021
Or copy this URL: https://www.metalroofing.com/spirit/comment/25738/find/Can you send me a photo of what you're seeing please? [email protected]
Isaiah Industries, Inc.
11/2/2021
Or copy this URL: https://www.metalroofing.com/spirit/comment/25739/find/Roof detail.pdf
11/2/2021
Or copy this URL: https://www.metalroofing.com/spirit/comment/25740/find/Thanks. I have a better understanding now. Have you talked to the manufacturer of the acoustical panel? My best guess is water vapor is passing through it and condensing someplace in the assembly and the corrosion is occurring. I'd ask the panel manufacturer if they can come do a site inspection.
Isaiah Industries, Inc.
11/2/2021
Or copy this URL: https://www.metalroofing.com/spirit/comment/25741/find/Yes, they have done evrything according to specs.
We believe it could be the 1000 holes they drilled in it that once drilled it created a exposed galvanizing. But simply, that it holds too much condensation and the design should have a rubber barrier between the decking and wood, and there should have been 2 inches of insulation to help control the condensation.
Simply: decking supplied per specs, deck installation per specs, wood installation per specs, standing seam roof supplied and installed per specs.
Everybody is at a loss.
11/2/2021
Or copy this URL: https://www.metalroofing.com/spirit/comment/25742/find/I agree that I was leading toward it coming from moisture dripping down against the perfed holes and then causing corrosion around the holes. This is an unusual application and normal dynamics don't come into play which would protect the exposed steel edges.
Isaiah Industries, Inc.
11/2/2021
Or copy this URL: https://www.metalroofing.com/spirit/comment/25743/find/