D.C. Mun. Regs. tit. 25, r. 25-D807
To facilitate cleaning, floors, workrooms, and passageways shall be kept free from protruding nails, splinters, loose boards, and unnecessary holes and openings.
Except as specified in section 807.3, attachments to walls and ceilings such as light fixtures, mechanical room ventilation system components, vent covers, wall mounted fans, decorative items, and other attachments shall be easily cleanable.
In public areas, wall and ceiling surfaces and decorative items and attachments that are provided for ambiance need not meet the requirements of section 808.1 if they are kept clean.
Studs, joists, rafters and beams shall not be exposed in bathrooms, restrooms, locker rooms, toilet rooms, on-site laundry areas, food areas, or in areas subject to moisture.
D.C. Mun. Regs. tit. 25, r. 25-D807