I'm heading to a sheet rock inspection at a new eye clinic. The plans show 5/8" gypsum on the walls and ceiling. The contractor has installed standard 1/2" gypsum throughout. The roof system is engineered trusses at 24" O.C. The IBC references GA-216 and ASTM C 840 which I don't have. However, 1/2" gyp is listed in Table 2508.5. What is confusing me is that the IRC only allows standard 1/2" gypsum with joists at 16" O.C. max if water based texture material is used; 5/8" gyp or 1/2" sag resistant required with trusses at 24" O.C. with water based texture (Table R702.3.5, footnote d). I plan to kick it back to the architect on my inspection report.