3 Story apartment building, Table R402..1.2 or C402.1.3 ?

[khsmith55]

2015 IECC, Zone 6, 3 Story apartment building with a slab on grade and "frost" walls. Confused as to which Table to use, R402.1.2 or C402.1.3 for R occupancy. Need direction on exterior walls and un-heated slab on grade. For exterior walls R402.1.2 calls for R20+5 where C402.1.3 calls for R20+3.8, which one should I use. For un-heated slab on grade R402.1.2 calls for R10, 4' (is this vertical for 4' ?) and C402.1.3 calls for R-15 for 24" below (again, is the "24" below" for vertical insulation ?). The building is NOT really A mixed-use building but all apartments with a "small" accessory Community Room (B Occupancy).

Thanks in advance
Ken

 

[RLGA]

Read the definition of a residential building in Chapter 2--that should give you your answer. If your building meet conforms to that definition (and I'm sure it does), then you comply with Chapter 4 {RE}.