We have a project in an existing 3 story fully sprinklered business occupancy Type II (000) building (unprotected steel beams and bar joists) that we are planning to renovate to an Ambulatory Surgery Center on part of the middle floor. According to LSC NFPA 2012 220.127.116.11.4 the project requires an one hour Occupancy separation at the perimeter walls and also at the floors directly above and below the surgery center. The building has a 6" concrete slab on metal deck that easily meets the 1 hour equivalent rating required per the 2012 IBC Table 718.104.22.168 and we will call for any openings and perimeters to be filled to maintain a 1 hour rating. My understanding is that NFPA does not have the same equivalency as the IBC and the AHJ may not except the IBC methodology or results.
It would be difficult to achieve a 1 hour separation in the area that we are renovating, but it would be very difficult and expensive to go into the existing tenant space below and try to install a 1 hour occupancy separation. above the ceiling in this occupied space.
Is there a mechanism that would allow an AHJ to accept the existing slab as a 1 hour occupancy separation?