D.C. Mun. Regs. tit. 11-K, § 224
2240.1 The maximum permitted lot occupancy in the SEFC-3 zone shall be seventy-five percent (75%).
2240.2 A building occupied by both residential and non-residential preferred uses provided in accordance with Subtitle K § 207.3 shall be permitted one hundred percent (100%) lot occupancy for the ground and second stories.
2240.3 No public recreation and community center shall occupy more than twenty percent (20%) of the lot upon which it is located; except that it may occupy up to forty percent (40%) if approved by the Zoning Commission, provided that the agency shows that the increase is consistent with the preservation of open space.
SOURCE: Final Rulemaking published at 63 DCR 2447, 3176 (March 4, 2016 – Part 2).