You can add a restroom to a warehouse, but it takes a permit and plans. The plumbing code counts fixtures from the occupant load, at one toilet and one sink per 100 people for storage and factory uses. Federal workplace rules can require more toilets. The work needs water, drain and vent lines, often through the slab.
How many restrooms does a warehouse need?
Section 403.1 of the 2024 IPC says plumbing fixtures must be provided in the minimum number shown in Table 403.1, based on the actual use of the building or space. The table lists classifications, and the ones that matter here are these. Numbers are per sex unless noted.
| Use | Water closets | Lavatories | Drinking fountains |
|---|---|---|---|
| Storage (warehouses, storehouses, freight depots, low and moderate hazard) | 1 per 100 | 1 per 100 | 1 per 1,000 |
| Factory and industrial (fabricating, assembly or processing) | 1 per 100 | 1 per 100 | 1 per 400 |
| Business (offices, light industrial and similar) | 1 per 25 for the first 50, then 1 per 50 | 1 per 40 for the first 80, then 1 per 80 | 1 per 100 |
Each of those uses also lists one service sink. The table's first note says the fixtures shown are based on one fixture being the minimum for the number of persons indicated or any fraction of that number. Note "a" adds that the number of occupants comes from the International Building Code. Section 403.1.1 says to divide the total occupant load in half to find the load of each sex, unless approved data show a different split, and to apply the ratio to each half.
Many warehouses have an office at the front. The office area counts as a business use, which the table describes as including office buildings and light industrial uses, and the ratios for business are much tighter than for storage. A designer splits the building by use, counts each part and adds the totals.
Here is a simple example. Suppose a building has an occupant load of 60 in a storage use. Half is 30 of each sex. At one water closet per 100, that is 1 water closet and 1 lavatory for each sex, plus a drinking fountain and a service sink. The code would be satisfied with two water closets in total.
Does the workplace safety rule ask for more? Yes, it can. The federal sanitation standard, 29 CFR 1910.141, says toilet facilities "shall be provided in all places of employment in accordance with table J-1," and Arizona adopts the general industry standards. For 56 to 80 employees, Table J-1 calls for at least 4 water closets, and the number for each sex is based on the number of employees of that sex. So a warehouse with 60 employees that meets the IPC count of two toilets in total could still be short under the worker rule. Design for the stricter of the two.
Do you need separate rooms for men and women? Section 403.2 of the IPC calls for separate facilities for each sex, with exceptions. Phoenix amends this section. Under the Phoenix version, separate facilities are not required in structures or tenant spaces with a total occupant load, including employees and customers, of 15 or fewer. They are also not required in business occupancies with a maximum occupant load of 50 or fewer, or in mercantile occupancies with a maximum occupant load of 100 or fewer. Single-user rooms that meet Section 403.1.2, or rooms designed for use by all persons regardless of sex with the privacy features the code lists, also do not have to be designated by sex. A small warehouse team can often use one or two single-user rooms.
Where can the restroom go?
Location has its own rules, and warehouses get some relief.
- Distance and floors. Section 403.3.3 says required public and employee toilet facilities must be "not more than one story above or below the space required to be provided with toilet facilities," and the path of travel must not exceed 500 feet. There are exceptions. The distances for required employee facilities in factory and industrial occupancies can exceed that if approved. So can the location and distance for public and employee facilities in Group S storage occupancies, if approved. In a large building, that approval can matter.
- Public access. Section 403.3.1 says the route to required public toilet facilities "shall not pass through kitchens, storage rooms or closets." If customers or drivers will use the restroom, plan a route that stays out of the storage area.
- Doors and privacy. Section 403.3.6 says the egress door of a multiple-occupant toilet room shall not be lockable from the inside, with an exception where it can be locked only by authorized personnel, opened from the inside and unlocked from outside. The federal standard also says each water closet must occupy a separate compartment "with a door and walls or partitions between fixtures sufficiently high to assure privacy."
- Sinks and soap. The federal standard says each lavatory must have hot and cold running water, or tepid running water, and that hand soap or a similar cleansing agent must be provided. That means the new room needs hot water, not only a cold line.
What does the plumbing work involve?
The fixtures are the small part. The larger part is getting water in and waste out.
- 1A design and a permit. A commercial restroom addition needs plans and a plumbing permit from your city. Our page on the Phoenix commercial plumbing tenant improvement permit explains the Phoenix process, and our page on who can pull a commercial plumbing permit in Arizona covers who applies.
- 2A place to connect the drain. A restroom needs a drain that reaches the building drain, at a slope that works. In a building with a slab, the plumber cuts the concrete, trenches, lays the pipe and patches the slab. If the building drain is far away or too high, the design may need a pump. See whether a building needs a lift station or sewage ejector pump.
- 3Vents. Each fixture needs a vent path to the roof or to an approved connection.
- 4Water supply. A new hot and cold water branch, with a water heater sized for the lavatories. Ask the designer whether a small point-of-use heater is enough for a single sink.
- 5Backflow protection and shutoffs. New fixtures need the required valves and protection.
- 6Accessibility. Many commercial restrooms must be accessible. Our guide to ADA commercial restroom plumbing covers fixture heights and clearances that affect the plumbing rough-in.
- 7Inspections. Expect the city to inspect the work at set stages and to approve the finished space, so ask which inspections it requires before anyone patches the slab.
If you rent, get the landlord's written approval first. Our page on commercial tenant improvement plumbing lists the other plumbing items that often ride along with a build-out, and how many plumbing fixtures a commercial space needs shows the same counting method for other uses.
HQ Plumbing and Air can walk your space, check where the building drain and water lines are, and lay out what a new restroom would take. We are licensed and insured, we give free estimates, and you get the price up front before any slab is cut.