318.1 The depth of a rear yard shall be measured as the mean horizontal distance between the rear line of a building and the rear lot line, except as provided elsewhere in this title. For purposes of measuring the rear yard, the rear line of a building shall be a mean horizontal distance starting at the point where the principal building area, as defined in Subtitle B § 312, extends furthest from the front lot line.318.2 Within a rear yard, the minimum required rear yard depth shall be measured as the mean horizontal distance between the rear line of a building and the rear lot line, except as provided in Subtitle B §§ 318.4 through 318.8 and elsewhere in this title .318.3 The required rear yard shall be unoccupied for the full width of the lot, except as specifically authorized in this title.318.4 In the R, RF, and RA zones, the depth of a required rear yard shall be measured as the mean horizontal distance from the rear line of a building toward the rear lot line for the full width of the lot, except as provided in Subtitle B §§ 318.5 through 318.8.318.5 In the case of a lot that is triangular or irregularly shaped, the furthermost point or line from the street lot line shall be deemed the point or line from which the required rear yard shall be measured.318.6 Where the rear lot line is not parallel to the street lot line, or where there are more than one (1) rear lot lines that intersect at a point at an angle greater than ninety degrees (90°), the required rear yard shall be measured as a vertical plane along a line measured in from the rear lot line at a point equidistant from the side lot lines.318.7 Where a lot does not have a rear lot line, such as when the side yards converge at a point, or where the rear lot lines intersect at an angle less than ninety degrees (90°), a required rear yard shall be measured as an arc from the point opposite the front lot line(s).318.8 Where there is more than one (1) rear lot line generally parallel to the front lot line but separated by a lot line generally perpendicular to the rear lot lines, then the required rear yard shall be measured from the rear lot line more distant from the front lot line, and measured across the full width of the property to where it intersects both side lot lines.318.9 In the case of a corner lot in any D zone other than the D-1-R zone, a court

complying with the width requirements for a closed court as specified in Subtitle I § 207.1 and Subtitle B § 324 may be provided in lieu of a rear yard. For the purposes of this section, the required court shall be provided above a horizontal plane twenty-five (25) feet above the mean elevation of the rear lot line.

318.10 In the case of a corner lot in the MU-1, MU-2, MU-8, MU-9, MU-15, NMU-8B/H-H, and CG-3 zones, a court complying with the width requirements for a closed court as applicable for each zone may be provided in lieu of a rear yard. For the purposes of this section, the required court shall be provided above a horizontal plan beginning not more than twenty feet (20 ft.) above the curb grade opposite the center of the front of the building and the width of the court shall be computed for the entire height of court.

318.11 In the case of a through or corner lot abutting three (3) or more streets, the depth of rear yard may be measured from the center line of the street abutting the lot at the rear of the structure.

SOURCE: Final Rulemaking published at 63 DCR 2447, 2650 (March 4, 2016 – Part 2); as amended by Final Rulemaking published at 63 DCR 10620 (August 19, 2016); as amended by Final Rulemaking published at 63 DCR 10932 (August 26, 2016); as amended by Final Rulemaking published at 64 DCR 22 (January 6, 2017); as amended by Final Rulemaking published at 64 DCR 7264 (July 28, 2017); as amended by Final Rulemaking published at 70 DCR 011297 (August 25, 2023); as amended by Final Rulemaking published at 72 DCR 006195 (May 23, 2025); as amended by Final Rulemaking published at 72 DCR 009494 (September 5, 2025).