722.5.1.2 Gypsum wallboard protection.
BC § 722.5.1.2
The fire resistance of structural steel columns with weight-to-heated-perimeter ratios (W/D) less than or equal to 3.65 and that are protected with Type X gypsum wallboard shall be permitted to be determined from the following expression: (Equation 7-12) where: R = Fire resistance (minutes). h = Total thickness of gypsum wallboard (inches). D = Heated perimeter of the structural steel column (inches). W' = Total weight of the structural steel column and gypsum wallboard protection (pounds per linear foot). W' = W + 50hD/144.













