In the R-1A/WH and R-1B/WH zones, all residential buildings shall have a front setback equal to or greater than the average setback of all structures on the same side of the street in the block where the building in question is located as depicted in the map entitled, "Required Front Yard Setbacks," which is a part of this zone and located in the Office of Zoning and in the Office of the Zoning Administrator at the Department of Buildings.
D.C. Mun. Regs. tit. 11, r. 11-D702