D.C. Mun. Regs. tit. 14, r. 14-103
If any premises (or part of any premises) occupied by a housing business does not comply with the provisions of this subtitle, or a violation of this subtitle is permitted to continue in the premises, the Director, after reasonable notice to the operator, in his or her discretion, may place upon the entrance to that part of the premises found to be in violation, a placard declaring the premises or part of the premises to be unfit for human habitation.
A placard, after being posted under the provisions of subsection 103.1, shall not be removed by any unauthorized person.
In the case of apartments and tenements only, thirty (30) days after the date of placarding under subsection 103.1, it shall be unlawful for any operator to permit the occupancy of or for any person to occupy that apartment or tenement (or the affected part of that apartment or tenement) until the placard is removed by the Director.
D.C. Mun. Regs. tit. 14, r. 14-103