D.C. Mun. Regs. tit. 14, § 1003
1003.1 The entrance door to each rooming unit shall be provided with a lock.
1003.2 A key for each rooming unit shall be furnished to each respective roomer.
1003.3 A duplicate key or keys shall be retained by the proprietor or manager.
1003.4 The proprietor or manager shall have access to all rooms at all reasonable hours.
SOURCE: The Housing Regulations of the District of Columbia, 5G DCRR § 4106, Commissioners' Order 55-1503 (August 11, 1955).