The maximum permitted height of a penthouse or rooftop structure, except as limited in Subtitle C § 1501 on the roof of a single household dwelling or flat, shall be twelve feet (12 ft.); except fifteen feet (15 ft.) shall be permitted for penthouse mechanical space, and the maximum number of stories shall be one (1).
A penthouse or rooftop structure permitted by this section shall contain no form of habitable space, other than ancillary space associated with a rooftop deck.
D.C. Mun. Regs. tit. 11, r. 11-G502