UL class A fire roof and polyiso or foam
severaltypesofnerd
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Could someone help with detailed specifications for top of deck insulation, in an area that requires a Class A roof assembly? With a vented roof the details are easy, only requiring ember safe vents and a fiberglass slip sheet under metal. For foam it is a bit more murky.
I see some details involving https://www.rmax.com/ultra-max Rmax Ultra-Max, but so far nothing with Polyiso.
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Hope this helps. i belive this might help.
check out dow thermax , only sold trough distributors or building supply stores. in my metro area there were only 2 guys , and only one was willing to sell small qty's.
http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0944/0901b80380944bea.pdf?filepath=styrofoam/pdfs/noreg/179-00011.pdf?filepath=styrofoam/pdfs/noreg/179-00011.pdf&fromPage=GetDoc
For Class A roof assemblies - the building department like to see the UL TGFU number
http://productspec.ul.com/search.php?type=listing&listing=TGFU&pagenum=11 is a link to the UL page for roofing mgfs. The documents list the roof assembly and required layers to get the needed rating.
So to work it backwards from the roofing type to the UL document and then the required assembly for the rating.
here is a sample from the UL link
Class A - Mechanically Fastened
6. Deck: C-15/32
Incline: 4
Insulation (Optional): — Johns Manville "ENRGY-2", Firestone Building Products "ISO 95+GL", Apache "Pyrox" and Atlas Roofing "ACFoam II", polyisocyanurate, 2 in. (min), Roxul "Toprock" or UL Classified polystyrene insulation, any thickness, loose laid or mechanically attached.
Barrier: — Two plies Atlas Roofing "FR-50" or min 1/4 in. G-P Gypsum DensDeck® with all joints staggered 6 in. from plywood joints.
Membrane: — "REZPROOF 111, 45 through 60 mil".
Here is what I got from my metal supplier, responsive to the above. TGFU.R9697
System 9 is on point, but seems to be incomplete, with no WRB.
It seems you roof will need a layer of plywood above the insulation to provide attachment for the metal roof panels. Using a 2' screw thru foam to attach a roof doesn't seem like it would work. It will need to be designed to take the weight of any solar panels, to keep them and the metal roof panel from sliding off the roof. The Versashield is an underlayment. Look at the ICC-ESR-2053 Report
This type of work will need a building permit, so you will need plans & plan check. The person you hire to help with plans will have the knowledge you need.