D.C. Mun. Regs. tit. 25, r. 25-C605
Toilet room floors shall be constructed of sealed concrete or other nonabsorbent materials with a smooth, slip-resistant surface to insure thorough cleaning.
The intersection of floors, walls, panels, stalls, or barriers shall be covered or sealed with waterproof materials.
Walls, panels, stalls, or barriers between toilet facilities, shower facilities, and dressing rooms, shall be made of durable materials not subject to water damage, and shall be designed so that a waterway is provided between the wall, panel, stall, barrier and the floor to permit thorough cleaning of the wall, panel, stall, barrier and floor areas with hoses and brooms.
Dressing room floors shall be made of the durable materials, not subject to water damage throughout.
Floor drains shall be provided, and floors shall be sloped not less than 1/4 inch per foot toward the drains to ensure positive drainage.
Carpets, duckboards and footbaths are prohibited in toilet facilities, shower facilities, and dressing rooms.
D.C. Mun. Regs. tit. 25, r. 25-C605