Fire-Rated Access Door for walls & ceilings. Drywall Bead. 18 ga. steel, Frame is 16 ga. steel, 1" wide perforated flange of 24 ga. galvanized material for mounting purposes, 2½"deep, Insulation is 2" thick mineral wool (ThermaFiber®), between two pieces of 22 ga. steel. Williams Brothers FR 820 Series Drywall Fire Rated Access Door This Fire Rated Access Door can be used in drywall wherever it is necessary to provide service access to shafts and any other...