IBC Plumbing Fixture Requirements: Minimum Counts by Occupancy

TL;DR — Key Takeaways

• IBC Chapter 29 requires minimum plumbing fixture counts based on occupancy group and occupant load, using Table 2902.1 as the primary reference.

• The IBC sets minimums only. The International Plumbing Code (IPC) governs the design, sizing, and installation of those fixtures. Both codes apply.

• Fractional fixture counts round up — always.

• Separate facilities for each sex are required in most occupancies. Key exceptions: 15 or fewer total occupants; mercantile with 100 or fewer; business with 25 or fewer.

• Multi-user/gender-neutral facilities: Fixture count calculated at 100% of total occupant load.

• Single-user toilet rooms count toward the total required fixture count.

• Key occupancy thresholds from Table 2902.1:

• Group A-1 (theaters): 1 WC per 125 (male) / 65 (female)

• Group A-2 (restaurants): 1 WC per 75 (both sexes)

• Group B (business): 1 WC per 25 (first 50 occupants, male); 1 per 25 (female)

• Group E (educational): 1 WC per 50 (male); 1 per 35 (female)

• Group I-2 (healthcare): 1 WC per patient room

• Group R-2 (residential): 1 WC per dwelling unit

• IBC 2024 addition: New occupancy categories in Table 2902.1 for ambulatory care and outpatient facilities.

What IBC Chapter 29 Covers

IBC Chapter 29 governs plumbing systems in buildings — specifically, it sets the minimum number of plumbing fixtures required based on occupancy and occupant load. It does not govern how those fixtures are designed, installed, or maintained — that is the domain of the International Plumbing Code (IPC).

The core provision is §2902.1: "Plumbing fixtures shall be provided in the minimum number as shown in Table 2902.1 based on the actual use of the building or space."

Two codes, two different jobs:

• IBC Chapter 29 / Table 2902.1 → How many fixtures are required

• IPC (International Plumbing Code) → How fixtures are installed, sized, and drained

Both apply on every project.

How Table 2902.1 Works: The Four-Step Method

Step 1 — Determine the occupancy classification

Fixture minimums are listed by IBC occupancy group. The classification from Chapter 3 drives the row used in Table 2902.1.

For mixed-occupancy buildings, calculate each occupancy's fixture requirements separately based on that occupancy's portion of the occupant load, then sum the results.

Step 2 — Determine the design occupant load

Use the IBC Chapter 10 occupant load determination (Table 1004.5) for each space. This is the same occupant load used for egress design — not a separate calculation.

Step 3 — Apply the Table 2902.1 fixture ratios

Table 2902.1 provides minimum fixture counts per number of occupants, typically broken down by:

• Water closets (male and female separately — counts often differ)

• Urinals (male; can substitute for up to 67% of male water closet requirements)

• Lavatories

• Bathtubs/showers (primarily Group I and R)

• Drinking fountains (typically 1 per 100 occupants)

• Service sinks (typically 1 per building)

Step 4 — Apply the rounding rule and split by sex

Fractional results always round up to the next whole number. When calculating for multiple occupancies, the fractions are summed first, then rounded up once.

Gender split: The Table 2902.1 male and female ratios apply to 50% of the occupant load each, unless approved statistical data supports a different distribution.

Key Fixture Minimums by Occupancy Group

Group A — Assembly

A-1 (theaters, concert halls, motion picture theaters):

• Water closets (male): 1 per 125 (first 1,000 occupants); 1 per 200 above 1,000

• Water closets (female): 1 per 65 (first 500 occupants); 1 per 100 above 500

A-2 (restaurants, nightclubs, bars):

• Water closets (male): 1 per 75

• Water closets (female): 1 per 75

A-3 (museums, libraries, recreation centers, gymnasiums):

• Water closets (male): 1 per 125

• Water closets (female): 1 per 65

A-4/A-5 (coliseums, arenas, stadiums, outdoor venues):

• Water closets (male): 1 per 75 (first 1,500); 1 per 150 above 1,500

• Water closets (female): 1 per 40 (first 1,500); 1 per 75 above 1,500

Group B — Business

• Water closets (male): 1 per 25 (first 50 occupants); 1 per 50 above 50

• Water closets (female): 1 per 25

• Lavatories: 1 per water closet

• Drinking fountains: 1 per 100 occupants

The Group B exception: Separate gender facilities not required for 25 or fewer total occupants.

Group E — Educational

• Water closets (male): 1 per 50

• Water closets (female): 1 per 35

• Lavatories: 1 per water closet

Group I — Institutional

Group I-1 (assisted living):

• Water closets: 1 per 10 residents

• Bathtubs/showers: 1 per 8 residents

Group I-2 (hospitals, nursing facilities):

• Water closets: 1 per patient sleeping room

Group I-3 (detention and correctional):

• Water closets: 1 per cell or 1 per 15 in day rooms

• Fixtures for employees must be separate from facilities for inmates

Group R — Residential

Group R-1 (hotels): 1 water closet per sleeping unit (with private bath)

Group R-2 (apartments):

• Water closets: 1 per dwelling unit

• Lavatories: 1 per dwelling unit

• Bathtubs or showers: 1 per dwelling unit

• Kitchen sinks: 1 per dwelling unit

Group M — Mercantile

• Water closets (male): 1 per 500 (first 1,500); 1 per 750 above 1,500

• Water closets (female): 1 per 300 (first 1,500); 1 per 500 above 1,500

Mercantile exception: Separate gender facilities not required for 100 or fewer total occupants.

Key Rules Beyond the Table

Urinal Substitution

Male water closets may be replaced by urinals at a rate of up to 67%. At least 1 male water closet must always remain regardless of urinal count.

Separate Facilities — When Not Required

Separate gender facilities are not required when:

• Total occupant load is 15 or fewer

• Mercantile occupancy with 100 or fewer total occupants

• Business occupancy with 25 or fewer total occupants

• Dwelling units and sleeping units

Drinking Fountains: The ADA Interaction

Where drinking fountains are provided, ADA Standards require at least one accessible (wheelchair reach range) and one for standing users ("hi-lo" fixture). This is an ADA requirement that applies independently of the IBC Table 2902.1 count.

Single-User Toilet Rooms

Single-user toilet rooms count toward the total required fixture count and can be deducted proportionately from gendered requirements.

Adult Changing Stations (IBC 2024)

IBC 2024 added requirements for adult changing facilities in certain occupancies for adults with disabilities requiring assisted changing. These are in addition to Table 2902.1 minimum fixture counts.

IBC vs. IPC: How the Two Codes Divide Responsibilities

Question	Governing Code
How many toilets are required?	IBC Chapter 29 / Table 2902.1
What size drain pipe serves each fixture?	IPC Chapter 7 (fixture units)
What are the clearances in front of fixtures?	ICC A117.1 (ADA accessibility)
What type of flush valve is required?	IPC Chapter 4 (fixture standards)
Can fixtures share a vent stack?	IPC Chapter 9 (vents)

Table 2902.1 fixture minimums are the starting point — ADA, OSHA, and state-specific amendments frequently add requirements that change the total fixture count. Melt Code lets you search all applicable requirements in one place.

Cross-reference IBC Chapter 29, IPC, and ADA compliance for your project on Melt Code → meltplan.com/code

Frequently Asked Questions

Q: Does the IBC tell me how many toilets a restaurant needs?

Yes — for Group A-2 occupancy (restaurants), Table 2902.1 requires 1 water closet per 75 occupants for both male and female. A restaurant with 150 occupants requires 1 male WC and 1 female WC (75 occupants each / 75 = 1 each). Note that the IPC also applies for installation, and local health codes may impose separate requirements.

Q: If I provide a family restroom, can I reduce gendered restrooms?

Yes, with limitations. Single-user toilet rooms count toward the total required fixture count and can be deducted proportionately from gendered requirements. A family restroom cannot entirely replace separate men's and women's facilities in large occupancies.

Q: Are urinals required by the IBC?

Urinals are not required — they are optional substitutes for male water closets at a rate of up to 67%. Providing urinals effectively reduces the number of male water closet stalls required. The minimum of 1 male water closet must always be maintained.

Q: What happens if my occupancy isn't listed in Table 2902.1?

IBC §2902.1 states: "Uses not shown in Table 2902.1 shall be considered individually by the code official." Work with the AHJ to determine appropriate fixture counts based on the most analogous listed occupancy.

Q: Does the IBC fixture count include employee and customer restrooms separately?

The IBC Table 2902.1 count is based on total occupant load — employees and customers combined. OSHA separately mandates minimum employee toilet facilities under 29 CFR 1910.141 for general industry. In most commercial buildings, the IBC count exceeds the OSHA minimum, but verify both for industrial facilities.

Q: Are drinking fountains required in all buildings?

Table 2902.1 requires drinking fountains based on occupancy (approximately 1 per 100 occupants). Small occupancies below certain thresholds may be exempt. Where provided, ADA Standards require accessible hi-lo fixtures.

• IBC Occupancy Classifications — Groups A Through U

• ADA Accessible Restroom Requirements

• IPC — International Plumbing Code Overview

• IBC International Building Code — Complete Hub