IBC Design 721.1(1) 1-7.2

2-Hour Fire Rated Steel columns and all of primary trusses — Three layers of 5/8" Type X gypsum wallboard.First and…

IBC Table 721.1(1), Item 1-7.2 (Steel columns and all of primary trusses): protection by Three layers of 5/8" Type X gypsum wallboard.First and second layer held in place by 1/8" diameter by 1-3/8" long ring shank nails with 5/16" diameter heads spaced 24" on center at corners. Middle layer also secured with metal straps at mid-height and 18" from each end, and by metal corner bead at each corner held by the metal straps. Third layer attached to corner bead with 1" long gypsum wallboard screws spaced 12" on center. Minimum insulating material thickness — 2-hr: 1-7/8". Prescriptive protection from the adopted building code — see table footnotes for conditions.