Interpretation #7185

Is it the intent of 912.5.3 to require a 1 hour separation for the following condition: Existing building - 2 story, 4500sf +- per floor, type 3B construction, Exterior walls masonry, 1st floor-Slab on grade, Second floor –conc. flr./metal deck/bar joists, Roof- metal deck/bar joist. Building is fully sprinklered. Building built under 2001 FBC as office building, no UL separation rating on second floor construction. New use proposed for 1st floor is A-2 Banquet use (no cooking equipment) for the restaurant in adjacent building. 2nd floor to remain business occupancy. FBC Existing, Section 912.5 – A-2 is a higher hazard to Office/ Business use. Is it correct in that this would be a separated mixed use building? Would therefore be required to provide a 1 hour separation on the ceiling/2nd floor assembly between the proposed change of occupancy of the 1st floor to A-2 and the 2nd floor existing B occupancy as per 912.5.3?