722.2.1.1 Cast-in-place or precast walls.
BC § 722.2.1.1
The minimum equivalent thicknesses of cast-in-place or precast concrete walls for fire-resistance ratings of 1 hour to 4 hours are shown in Table 722.2.1.1. For solid walls with flat vertical surfaces, the equivalent thickness is the same as the actual thickness. The values in Table 722.2.1.1 apply to plain, reinforced or prestressed concrete walls. Table 722.2.1.1Minimum Equivalent Thickness of Cast-In-Place or Precast Concrete Walls, Load-Bearing or Nonload-Bearing Concrete TypeMinimum Slab Thickness (inches) for Fire-Resistance Rating of1 hour1 1/2 hours 2 hours 3 hours4 hoursSiliceous3.5 4.3 5.0 6.2 7.0 Carbonate3.2 4.0 4.6 5.7 6.6 Sand- lightweight2.7 3.3 3.8 4.6 5.4 Lightweight2.5 3.1 3.6 4.4 5.1 For SI: 1 inch = 25.4 mm.
