1/2” (12.7 mm) ToughRock® Fireguard C® or 1/2” (12.7 mm) DensArmor Plus® Fireguard C® gypsum board applied vertically to each side of 1” (25.4 mm) DensGlass® Shaftliner or ToughRock® Shaftliner with laminating compound combed over entire surface. Floor and ceiling track of wood or steel runners. Joints staggered. Test conducted with generic Type X board in December 1959. Contact GP Technical Service Hotline for a copy of the test report.