722.4.1 Masonry walls.
BC § 722.4.1
The fire-resistance rating of masonry walls shall be based upon the equivalent thickness as calculated in accordance with this section. The calculation shall take into account finishes applied to the wall and airspaces between wythes in multi-wythe construction. Table 722.4.1(1)Fire-Resistance Periods of Clay Masonry Walls Material TypeMinimum Required Equivalent Thickness for Fire Resistance a, b, c (Inches)1 hour2 hours 3 hours4 hoursSolid brick of clay or shale d2.73.84.96.0Hollow brick or tile of clay or shale, unfilled2.33.44.35.0Hollow brick or tile of clay or shale, grouted or filled with materials specified in Section 722.4.1.1.33.04.45.56.6 For SI: 1 inch = 25.4 mm. a. Equivalent thickness as determined from Section 722.4.1.1. b. Calculated fire resistance between the hourly increments listed shall be determined by linear interpolation. c. Where combustible members are framed in the wall, the thickness of solid material between the end of each member and the opposite face of the wall, or between members set in from opposite sides, shall be not less than 93 percent of the thickness shown. d. For units in which the net cross-sectional area of cored brick in any plane parallel to the surface containing the cores is at least 75 percent of the gross cross-sectional area measured in the same plane. Table 722.4.1(2)Fire-Resistance Ratings for Bearing Steel Frame Brick Veneer Walls or Partitions Wall or Partition AssemblyPlaster SideExposed (hours)Brick Faced Side Exposed (hours)Outside facing of steel studs: 1/2" wood fiberboard sheathing next to studs, 3/4" airspace formed with 3/4" × 1 5/8" wood strips placed over the fiberboard and secured to the studs; metal or wire lath nailed to such strips, 3 3/4" brick veneer held in place by filling 3/4" airspace between the brick and lath with mortar.Inside facing of studs: 3/4" unsanded gypsum plaster on metal or wire lath attached to 5/16" wood strips secured to edges of the studs.1.54Outside facing of steel studs: 1" insulation board sheathing attached to studs, 1" airspace, and 3 3/4" brick veneer attached to steel frame with metal ties every 5th course.Inside facing of studs: 7/8" sanded gypsum plaster (1:2 mix) applied on metal or wire lath attached directly to the studs.1.54Same as above except use 7/8" vermiculite – gypsum plaster or 1" sanded gypsum plaster (1:2 mix) applied to metal or wire24Outside facing of steel studs: 1/2" gypsum sheathing board, attached to studs, and 3 3/4" brick veneer attached to steel frame with metal ties every 5th course.Inside facing of studs: 1/2" sanded gypsum plaster (1:2 mix) applied to 1/2" perforated gypsum lath securely attached to studs and having strips of metal lath 3 inches wide applied to all horizontal joints of gypsum lath.24 For SI: 1 inch = 25.4 mm. Table 722.4.1(3)Values of Rn0.59 Rn0.59R (hours)11.021.5031.9142.27 Table 722.4.1(4)Coefficients for Plaster, Pl a Thickness of Plaster (inch)One SideTwo Sides1/20.30.65/80.370.753/40.450.90 For SI: 1 inch = 25.4 mm. a. Values listed in the table are for 1:3 sanded gypsum plaster. Table 722.4.1(5)Reinforced Masonry Lintels Nominal Lintel Width (inches)Minimum Longitudinal ReinforcementCover For Fire Resistance (inches)1 hour2 hours3 hours4 hours61 1/22NPNP81 1/21 1/21 3/4310 or more1 1/21 1/21 1/21 3/4 For SI: 1 inch = 25.4 mm. NP = Not permitted. Table 722.4.1(6)Reinforced Clay Masonry Columns Column SizeFire-Resistance Rating (hours)1234Minimum column dimension (inches)8101214 For SI: 1 inch = 25.4 mm.
