722.2.3 Concrete cover over reinforcement.
BC § 722.2.3
The minimum thickness of concrete cover over reinforcement in concrete slabs, reinforced beams and prestressed beams shall comply with this section. Table 722.2.3(1)Cover Thickness for Reinforced Concrete Floor or Roof Slabs (inches) Concrete Aggregate TypeFire-Resistance Rating (hours)RestrainedUnrestrained1 1 1/2234 1 1 1/22 34 Siliceous3/4 3/4 3/4 3/4 3/4 3/4 3/4 1 1 1/41 5/8 Carbonate3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 1 1/41 1/4Sand-lightweight or lightweight3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 1 1/41 1/4 For SI: 1 inch = 25.4 mm. Table 722.2.3(2)Cover Thickness for Prestressed Concrete Floor or Roof Slabs (inches) Concrete Aggregate TypeFire-Resistance Rating (hours)RestrainedUnrestrained1 1 1/2 234 1 1 1/22 34 Siliceous3/4 3/4 3/4 3/4 3/4 1 1/8 1 1/2 1 3/4 2 3/82 3/4Carbonate3/4 3/4 3/4 3/4 3/4 1 1 3/81 5/82 1/82 1/4Sand-lightweight or lightweight3/4 3/4 3/4 3/4 3/4 1 1 3/8 1 1/22 2 1/4 For SI: 1 inch = 25.4 mm. Table 722.2.3(3)Minimum Cover for Main Reinforcing Bars of Reinforced Concrete Beams c(Applicable to All Types of Structural Concrete) Restrained or Unrestrained aBeam Width b (inches)Fire-Resistance Rating (hours)11 1/22 3 4 Restrained or Unrestrained aBeam Width b (inches)Fire-Resistance Rating (hours)11 1/22 3 4 Restrained53/43/43/41 a1 1/4 a73/43/43/43/43/4≥103/43/43/43/43/4Unrestrained53/411 1/4——73/43/43/41 3/43≥103/43/43/4 11 3/4 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm. a. Tabulated values for restrained assemblies apply to beams spaced more than 4 feet on center. For restrained beams spaced 4 feet or less on center, minimum cover of 3/4 inch is adequate for ratings of 4 hours or less. b. For beam widths between the tabulated values, the minimum cover thickness can be determined by direct interpolation. c. The cover for an individual reinforcing bar is the minimum thickness of concrete between the surface of the bar and the fire-exposed surface of the beam. For beams in which several bars are used, the cover for corner bars used in the calculation shall be reduced to one-half of the actual value. The cover for an individual bar must be not less than one-half of the value given in Table 722.2.3(3) nor less than 3/4 inch. Table 722.2.3(4)Minimum Cover for Prestressed Concrete Beams 8 Inches or Greater in Width Restrained or Unrestrained aConcrete Aggregate TypeBeam Width b (inches)Fire-Resistance Rating (hours)1 1 1/22 3 4Restrained or Unrestrained aConcrete Aggregate TypeBeam Width b (inches)Fire-Resistance Rating (hours)1 1 1/22 3 4RestrainedCarbonate or siliceous81 1/21 1/21 1/21 3/4 a2 1/2 aCarbonate or siliceous≥121 1/21 1/2 1 1/2 1 1/2 1 7/8 aSand-lightweight81 1/21 1/2 1 1/2 1 1/2 2 aSand-lightweight≥121 1/21 1/2 1 1/2 1 1/2 1 5/8 aUnrestrainedCarbonate or siliceous81 1/21 3/42 1/25 c—Carbonate or siliceous≥121 1/21 1/21 7/8 a2 1/23Sand-lightweight81 1/21 1/223 1/4—Sand-lightweight≥121 1/21 1/21 5/822 1/2 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm. a. Tabulated values for restrained assemblies apply to beams spaced more than 4 feet on center. For restrained beams spaced 4 feet or less on center, minimum cover of 3/4 inch is adequate for 4-hour ratings or less. b. For beam widths between 8 inches and 12 inches, minimum cover thickness can be determined by direct interpolation. c. Not practical for 8-inch-wide beam but shown for purposes of interpolation. Table 722.2.3(5)Minimum Cover for Prestressed Concrete Beams of All Widths Restrained or Unrestrained aConcrete Aggregate TypeBeam Area bA (square inches)Fire-Resistance Rating (hours)1 1 1/2 2 3 4 Restrained or Unrestrained aConcrete Aggregate TypeBeam Area bA (square inches)Fire-Resistance Rating (hours)1 1 1/2 2 3 4 RestrainedAll40 ≤ A ≤ 150 1 1/21 1/22 2 1/2— Carbonate orsiliceous150 < A ≤ 300 1 1/21 1/21 1/21 3/42 1/2300 < A 1 1/21 1/21 1/21 1/22 Sand-lightweight150 < A 1 1/21 1/21 1/21 1/22 UnrestrainedAll40 ≤ A ≤ 150 2 2 1/2— — — Carbonate orsiliceous150 < A ≤ 300 1 1/21 3/42 1/2— — 300 < A 1 1/21 1/22 3 c4 cSand-lightweight150 < A 1 1/21 1/22 3 c4 c For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm. a. Tabulated values for restrained assemblies apply to beams spaced more than 4 feet on center. For restrained beams spaced 4 feet or less on center, minimum cover of 3/4 inch is adequate for 4-hour ratings or less. b. The cross-sectional area of a stem is permitted to include a portion of the area in the flange, provided the width of the flange used in the calculation does not exceed three times the average width of the stem. c. U-shaped or hooped stirrups spaced not to exceed the depth of the member and having a minimum cover of 1 inch shall be provided.
