D.C. Mun. Regs. tit. 25-B, § 1802
1802.1 Utility service lines and pipes shall not be unnecessarily exposed.
1802.2 Exposed utility service lines and pipes shall be installed so they do not obstruct or prevent cleaning of the floors, walls, or ceilings.
1802.3 Exposed horizontal utility service lines and pipes shall not be installed on the floor.
SOURCE: Final Rulemaking published at 56 DCR 5245 (July 3, 2009).