What sets the fixture count
IBC 2021 Section 2902.1 says plumbing fixtures are provided in the minimum number shown in Table 2902.1 based on the actual use of the building or space. Construction type governs fire-resistance and allowable area, stories above grade plane is a height limit, and gross floor area regardless of use ignores how the space is used. None of them sets the count.
Splitting the load and rounding
Section 2902.1.1 gives two steps:
- Divide the total occupant load in half to get the occupant load of each sex. A building with 150 occupants uses 150 ÷ 2 = 75 per sex. Applying the full 150 to each sex doubles the fixture count.
- Round fractions up to the next whole number. If the ratio gives 2.3 water closets per sex, provide 3. Rounding down to 2 is not allowed, and there is no basis for doubling to 4.
When separate facilities are not required
Section 2902.2 normally calls for separate facilities for each sex, with exceptions:
- Exception 2: structures or tenant spaces with a total occupant load of 15 or fewer. An office tenant of 14 qualifies. The threshold is 15, not 10, and it applies to any structure or tenant space.
- Exception 3: mercantile occupancies with a maximum occupant load of 100 or less. A store with 90 qualifies; a store with 150 does not.
The trap is carrying the 100 figure to other occupancies. An assembly space with 90 occupants does not get Exception 3. Only mercantile gets the 100 limit; the general exception for all structures is 15 or fewer.
Where toilet rooms may go
Section 2902.3 locates required employee and public toilet facilities:
- Not more than one story above or below the space served. Same story is not required, but first-floor toilets cannot serve a third-floor tenant two stories up.
- A path of travel of not more than 500 feet (152 m). 200 feet is not the limit.