D.C. Mun. Regs. tit. 25, r. 25-C6433
Sanitary facility floors shall be constructed of concrete or other nonabsorbent materials with a smooth, slip-resistant surface to insure thorough cleaning.
Carpets, duckboards and footbaths are prohibited.
The intersection between the floor and walls shall be covered where either is not made of waterproof materials or the intersection is not sealed waterproof.
Partitions between portions of the dressing room area, screened partitions, shower, toilet, and dressing room booths shall be of durable material, not subject to damage by water and shall be designed so that a waterway is provided between partitions and floor to permit thorough cleaning of the walls and floor areas with hoses and brooms.
Dressing facility floors shall be continuous throughout the areas.
Floor drains shall be provided, and floors shall be sloped not less than 1/4 inch per foot toward the drains to insure positive drainage.
D.C. Mun. Regs. tit. 25, r. 25-C6433