Except as provided in Subtitle K § 406.2, no rear yard shall be required for entirely non-residential buildings.
Notwithstanding Subtitle K § 406.1, an entirely non-residential building shall have a rear yard if:
The rear yard required by this section shall have a depth equal to the distance between the rear wall of the non-residential building and the facing wall of the residential building.
All residential buildings shall provide a rear yard in accordance with either Subtitle K §§ 406.5 or 406.6.
When the residential portion of a building begins at or below grade, the building shall provide a rear yard with a minimum depth of three inches (3 in.) per one foot (1 ft.) of vertical distance from the mean finished grade at the middle of the rear of the structure to the highest point of the main roof, but not less than twelve feet (12 ft.).
When the residential portion of a building begins above grade, the building shall provide a rear yard with a minimum depth of three inches (3 in.) per one foot (1 ft.) of vertical distance from the horizontal plane at which the residential use begins to the highest point of the main roof, but not less than twelve feet (12 ft.). The rear yard shall be provided at and above the horizontal plane at which residential use begins.
D.C. Mun. Regs. tit. 11, r. 11-K406