No side yard is required for a principal structure in a D zone; however, if a side setback is provided on any portion of the principal building, it shall comply with Subtitle B §§319 and 320, and shall be at least four feet (4 ft.) wide.
The Board of Zoning Adjustment may grant relief to the side yard requirements as a special exception pursuant to Subtitle X, Chapter 9.
The side yard regulations shall not apply to historic landmarks or contributing buildings within historic districts.
D.C. Mun. Regs. tit. 11, r. 11-I206