It should not have been classified as an A-3 use. Per 303.1.1 it should have been classified as a B use. If locally amended to require posting, post as described on the CO (i.e. 21).Sorry for the confusion. The numbers I was suing were for a 1,050 sf Fitness Room. At 50 sf per person (Table 1004.1.2), the occupancy would have been 21. (It ended up a little smaller). It was classified as A-3.
303.1.1 Small Buildings and Tenant Spaces
A building or tenant space used for assembly purposes with an occupant load of less than 50 persons shall be classified as a Group B occupancy.