D.C. Mun. Regs. tit. 11-K, § 605
605.1 Buildings within the StE-17 and StE-18 zones shall be setback not less than ten feet (10 ft.) from the property line that abuts Alabama Avenue and 13th Street.
605.2 No part of a building within the StE-17 and StE-18 zones shall project above a plane drawn at a forty-five degree (45°) angle from a line located fifty feet (50 ft.) directly above the property line that abuts Alabama Avenue.
SOURCE: Final Rulemaking published at 63 DCR 2447, 3176 (March 4, 2016 – Part 2).