D.C. Mun. Regs. tit. 14, § 1303
1303.1 The entrance door to each rooming unit shall be provided with a lock.
1303.2 A key to the unit shall be furnished to the respective occupant.
1303.3 A duplicate key or keys shall be retained by the licensee or manager who shall have access to all rooms at all reasonable hours.
SOURCE: The Housing Regulations of the District of Columbia, 5G DCRR § 7203, Commissioners' Order 53-1503 (August 11, 1955).