The International Existing Building Code (IEBC) is the I-Code that covers existing buildings in depth. While the International Building Code (IBC) covers changes of occupancy in existing buildings, the IEBC goes into much greater detail. When you’re doing a change of occupancy, see if your municipality has adopted it.
In the 2006 IEBC there is a table that lists the relative hazard with regards to egress. This allows you to evaluate if your change of occupancy is moving to a higher, lower or equal hazard. The categories are as follows:
1 (the highest hazard) is only for H occupancy
2 is for I-2, I-3 and I-4 occupancies
3 is for A, E, I-1, M, R-1, R-2 and R-4 occupancies
4 is for B, F-1, R-3 and S-1 occupancies
5 (the lowest hazard) is for F-2, S-2 and U occupancies