722.2.1.4 Walls with gypsum wallboard or plaster finishes.
BC § 722.2.1.4
The fire-resistance rating of cast-in-place or precast concrete walls with finishes of gypsum wallboard or plaster applied to one or both sides shall be permitted to be calculated in accordance with the provisions of this section. Table 722.2.1.4(1)Multiplying Factor for Finishes on Nonfire-Exposed Side of Wall Type of Finish Applied to Concrete or Concrete Masonry WallType of Aggregate Used in Concrete or Concrete MasonryConcrete: siliceous or carbonate Concrete Masonry: siliceous or carbonate; solid clay brickConcrete: sand- lightweight Concrete Masonry: clay tile; hollow clay brick; concrete masonry units of expanded shale and <20% sandConcrete: lightweight Concrete Masonry: concrete masonry units of expanded shale, expanded clay, expanded slag, or pumice < 20% sandConcrete Masonry: concrete masonry units of expanded slag, expanded clay, or pumicePortland cement-sand plaster1.000.75 a0.75 a0.50 aGypsum-sand plaster1.251.001.001.00Gypsum-vermiculite or perlite plaster1.751.501.251.25Gypsum wallboard3.002.252.252.25 For SI: 1 inch = 25.4 mm. a. For Portland cement-sand plaster 5/8 inch or less in thickness and applied directly to the masonry on the nonfire-exposed side of the wall, the multiplying factor shall be 1.00. Table 722.2.1.4(2)Time Assigned to Finish Materials on Fire-Exposed Side of Wall Finish Description Time (minute) Finish Description Time (minute) Gypsum wallbound 3/8 inch10 1/2 inch15 5/8 inch20 2 layers of 3/8 inch25 1 layer of 3/8 inch, 1 layer of 1/2 inch35 2 layers of 1/2 inch40 Type X gypsum wallboard 1/2 inch25 5/8 inch40 Portland cement-sand plaster applied directly to concrete masonrySee Note a Portland cement-sand plaster on metal lath 3/4 inch20 7/8 inch25 1 inch30 Gypsum sand laster on 3/8-inch gypsum lath 1/2 inch35 5/8 inch40 3/4 inch50 Gypsum sand plaster on metal lath 3/4 inch50 7/8 inch60 1 inch80 For SI: 1 inch = 25.4 mm. a. The actual thickness of portland cement-sand plaster, provided it is 5/8 inch or less in thickness, shall be permitted to be included in determining the equivalent thickness of the masonry for use in Table 722.3.2.
