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What can be done to get top of deck foam insulation, in a UL Class A rated roof assembly? Metal Sales lists the following:
TGFU.R9697 Roofing Systems
Class A: Deck: C-15/32 CDX or spaced sheathing
Incline: Unlimited Impact: 4
Insulation: — Rmax "Ultramax" 1 in. min, mechanically fastened. Panels: — Steel roofing panel, mechanically fastened.
But this seems strange as Ultramax is just a foam sheet with fiberglass attached, it's not a water barrier.
What order and type of layers are used for solid foam panels in general, and in the Class A situation?
Is this a new construction build or retrofit?
Old roof is transite asbestos.
New roof to be standing seam metal with 18 solar panels.
Attic is 30x50 foot, 6:12 pitch, all hip roof.
Looking for standard details for fascia and buildup of ply, foam, shield, for a Class A assembly for 1.5 or 2 inches of foam. Roofer says they can do metal direct on the foam, but don't know about Class A.
Re-roof. 6:12 pitch. Zip 94708 (local Fire Zone 2). Rotted rafter tails, so fascia will be spotty for gutter attachment already.
It's a re-reroof. 6:12 pitch. Climate Zone 3C (marine influenced). California Wildland Interface Code.
Bryce, my apologies for the delay in responding to your questions. I have needed to do a bit of research. I spoke to Andy Williams yesterday who is the Codes Director for Metal Construction Association (metal construction.org). I am sure that if you want to call him, he will be happy to try to help. However, what he told me was that, if you put foam on a roof assembly then it is going to have to be part of a tested assembly to see if it meets fire code requirements. I honestly do not think there has been much testing done in that area, especially for residential application. If Metal Sales is showing an assembly with foam that they say is fire rated, I would suggest contacting David Stermer with their company to see what light he can shed on it. It is unusual to put foam on top of a roof deck in residential though I can certainly see why in your case it is desirable.
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