Section Table 403.1/Minimum Plumbing Fixtures
IPC Table 403.1 establishes minimum plumbing fixture counts based on occupancy type and occupant load.
Table 403.1 specifies the minimum number of water closets, urinals, lavatories, drinking fountains, and other fixtures based on the building occupancy classification and the number of occupants. For assembly occupancies (A-1 through A-5), one water closet is required per 125 males and one per 65 females. For business occupancies (B), one water closet is required per 25 occupants for the first 50, then one per 50 thereafter. Occupant loads are calculated per IBC Section 1004.
Why this section exists
Adequate plumbing fixtures prevent unsanitary conditions, long wait times, and public health issues in buildings. The fixture counts are based on occupancy type because different building uses have different fixture demand patterns. Assembly occupancies require more fixtures per occupant than offices because the demand peaks sharply during intermissions. The male/female ratios reflect documented usage differences.
What plan reviewers look for
Plan reviewers calculate the required fixture count using the occupant load from the architectural drawings and the ratios from Table 403.1. They compare the calculated minimum against the fixtures shown on the plumbing floor plan. They also check that accessible fixtures are provided per ADA requirements and that fixture ratios account for the male/female split.
Common violations
Related IPC requirements
Section 604 covers fixture sizing that affects the water supply design. Section 403.4 covers the required number of accessible fixtures. IBC Section 1004 provides the occupant load used for fixture calculations. ADA Section 604 covers accessible water closet clearances.