It will permit "x occupants" in all occupancies except for those with male/female diversity (Group A - A-5, A-4, some A-3 and A-1, or approved by the building official as if for an all girls school). 2021 IPC Section 403.1.1 Exception 3 can benefit the total fixture count by not having to divide the occupancy in half first. Take an example of WC for business with an occupancy of 80. Current calc. divides occupants to 40/40. Each sex applies 1/25 for the first 50. This results in 1.6 WC for male and 1.6 WC for female. Round up. This will require a male toilet room with two WC and the same for female; 4 WC total. Using this exception, 80 occupants do not divide. 1/25 for the first 50 and 1/50 thereafter results in 2.6 WC. Here, 3 WC will satisfy 403.1.1 rather than 4 WC. Only caveat is that three single-user toilet facilities must be provided rather than one men's room and one women's room. Each single-user toilet facility shall be identified as being available for use by all persons regardless of their sex.
Now for a really interesting fact. Same parameters, except the occupant load is 50 (simplest example possible, but functional in more complex designs). 2021 Section 403.1.2 will permit two single-user toilet facilities in lieu of separate male and female toilet facilities. Agreed? The two single-user toilet facilities will be placed side-by-side in the business space, clustering them together. Now apply IBC 1109.2 Exception 3. This will require that only one of these rooms be accessible, not both. If these were identified as male and female, both would be required to be accessible.
