Base Layer: 5/8” (15.9 mm) ToughRock® Fireguard C® gypsum board or 5/8” (15.9 mm) DensArmor Plus® Fireguard C® gypsum panels applied perpendicular to I-shaped wood joists or wood and steel trusses, spaced 19.2” (488 mm) o.c. maximum, with 1-5/8” (41 mm) Type S drywall screws, 8” (203 mm) o.c. Resilient channels attached 16” (406 mm) o.c. through base layer perpendicular to joists or trusses with 1-7/8” (48 mm) Type S drywall screws. Middle Layer: 5/8” (15.9 mm) ToughRock Fireguard C gypsum board or 5/8” (15.9 mm) DensArmor Plus Fireguard C gypsum panels applied perpendicular to resilient channels with 1” (25.4 mm) Type S drywall screws 8” (203.2 mm) o.c. Screws located 1-1/2” (38 mm) to 2” (51 mm) and 5/8” (15.9 mm) to 3/4” (19 mm) from side and end joints respectively. Face Layer: 5/8” (15.9 mm) ToughRock Fireguard C gypsum board or 5/8” (15.9 mm) DensArmor Plus Fireguard C gypsum panels applied perpendicular to channels with 1-5/8” (41 mm) Type S drywall screws, 8” (203 mm) o.c. Joints in the face layer are offset 16” (406 mm) from those in the middle layer. 5/8” (15.9 mm) T&G plywood floor perpendicular to joists with adhesives and 8d cement coated nails 12” (305 mm) o.c.
