I’ll be installing R-10 rigid foam board on some crawlspace walls and I’m trying to avoid having to drywall over it. I’m wanting a fire rated, foil faced foam product such as Dupont Thermax or JM Ci Max. I’m having difficulty sourcing either product locally as the 2 listed suppliers in the area have both said I’d have to buy in pallet quantity even though I need 18 sheets. One supplier recommended Hunter Panels XCI 286 polyiso. The manufacturer lists it “NFPA 286 tested for exposed applications for interior wall or ceiling” They have other foil faced products listed as Class A “Flame Spread <25 per ASTM E 84” which is the same standard Thermax meets. So can I substitute the NFPA 286 standard for the ASTM E84 Standard? Has anyone used Hunter Panels?