IBC Design 721.1(2) 10-1.2

2-Hour Fire Rated Hollow (studless) gypsum wallboard partition — 1" regular gypsum V-edge full-length backing board attached to both…

IBC Table 721.1(2), Item 10-1.2 (Hollow (studless) gypsum wallboard partition): 1" regular gypsum V-edge full-length backing board attached to both sides of wood or metal top and bottom runners with nails or 1-5/8" drywall screws at 24" on center. Minimum width of runners 1-5/8". Face layer of 1/2" regular full-length gypsum wallboard laminated to outer faces of backing board with approved laminating compound. Minimum finished thickness (face-to-face) — 2-hr: 4-5/8 (d)". Prescriptive assembly from the adopted building code — thicknesses are code minimums, see table footnotes for conditions.