312. RULES OF MEASUREMENT FOR LOT OCCUPANCY

312 RULES OF MEASUREMENT FOR LOT OCCUPANCY 312.1 The building area, as defined by Subtitle B § 312.3, shall be subject to the lot occupancy standard prescribed in the development standards table for the zone in which the building is located. 312.2 Lot occupancy shall be calculated by dividing the total building area, as defined by Subtitle B § 312.3, of all buildings on a lot by the total area of the lot. 312.3 For the purposes of lot occupancy calculation, building area shall be the maximum horizontal projected area of a principal building and its accessory buildings, measured at the ground level of the buildings and measured from the exterior faces of exterior walls and from the center line of walls separating two (2) buildings. 312.4 For the purposes of calculating Lot Occupancy, building area shall not include: (a) Building components or appurtenances dedicated to the environmental sustainability of the building; (b) Cornices and eaves; (c) Sills, leaders, belt courses, and similar ornamental or structural features; (d) Awnings, serving a window, porch, deck, or door; (e) Uncovered stairs, landings no larger in size than that required by the building code, and wheelchair ramps or accessibility lifts that serve the main floor; (f) Chimneys, smokestacks, or flues; (g) Uncovered porches and decks that are no more than four feet (4 ft) in height above the ground level at any point; (h) Uncovered porches and decks that are more than four feet (4 ft) in height above the ground level at any point but level with or below the main floor of the building, to a maximum cumulative area of 200 sq. ft.; provided that this section shall not be used to exclude any portion of uncovered porches or decks from yard requirements; and Except for the RF zones, exterior balconies that do not exceed a projection of eight feet (8 ft.) beyond the exterior walls of the building. 312.5 Any railing required by the D.C. Construction Codes Supplement, Title 12 DCMR, that is required to project into the horizontal plane shall be permitted and shall not be included in the measurement of building area. 312.6 When adding a vertical addition to an existing building, each added story must comply with the required lot occupancy limitation. 312.7 In the case of a building devoted to both residential and nonresidential uses, the percentage of lot occupancy for residential uses may be calculated on a horizontal plane located at the lowest level where residential uses begin. SOURCE: Final Rulemaking published at 63 DCR 2447, 2650 (March 4, 2016 – Part 2); as amended by Final Rulemaking published at 63 DCR 10932 (August 26, 2016); as amended by Final Rulemaking published at 71 DCR 001527 (February 9, 2024); as amended by Final Rulemaking published at 73 DCR 009999 (July 10, 2026). District of Columbia Municipal Regulations Zoning Regulations of 2016: Definitions, Rules of Measurement, and Use Categories 11-B DCMR § 312