1800 SF storage warehouse with 6 units. All of these units, including parking spaces for vehicle storage, will be used for temporary storage, with users dropping off and picking up vehicles.
There are no plumbing fixture requirements for a "U" occupancy
If the building is limited to vehicle storage and you construct a one-hour fire barrier between the 6 units and your lease agreements spells out that it is strictly storage of the vehicle then the Rest Room is not required because it is a "U" occupancy.
[BG] PRIVATE GARAGE. A building or portion of a building in which motor vehicles used by the owner or tenants of the building or buildings on the premises are stored or kept,
without provisions for repairing or servicing such vehicles for profit.
SECTION 312
UTILITY AND MISCELLANEOUS GROUP U
312.1 General.
Buildings and structures of an accessory character and miscellaneous structures not classified in any specific occupancy shall be constructed, equipped and maintained to conform to the requirements of this code commensurate with the fire and life hazard incidental to their occupancy. Group U shall include, but not be limited to, the following:
Carports
Private garages
406.3.1 Classification.
Private garages and carports
shall be classified as Group U occupancies. Each private garage shall be not greater than 1,000 square feet (93 m2) in area.
Multiple private garages are permitted in a building where each private garage is separated from the other private garages by 1-hour fire barriers in accordance with Section 707, or 1-hour horizontal assemblies in accordance with Section 711, or both.
[P] 2902.3 Employee and public toilet facilities.
For structures and tenant spaces intended for public utilization, customers, patrons and visitors shall be provided with public toilet facilities. Employees associated with structures and tenant spaces shall be provided with toilet facilities. The number of plumbing fixtures located within the required toilet facilities shall be provided in accordance with Section 2902 for all users. Employee toilet facilities shall be either separate or combined employee and public toilet facilities.
Exception: Public toilet facilities shall not be required for:
1. Parking garages where operated without parking attendants.
[P] 2902.1 Minimum number of fixtures.
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. Uses not shown in Table 2902.1 shall be considered individually by the code official.