Johns Manville FSK-25 BI facing is a flame-retardant vapor barrier facing manufactured using lightweight aluminum foil (.0003" (9 micron)), fiberglass reinforcing yarn and natural kraft paper laminated together with a flame-retardant adhesive. It is coated with a thermoplastic asphalt coating on one side that is used to bond fiberglass insulation to the facing in a subsequent manufacturing process. FSK-25 BI facing is mold and mildew resistant for added product protection and is manufactured with a folded tab to provide stapling flanges for installation.