Side yard for a detached or semi-detached building containing one (1) or two (2) dwelling units shall be a minimum of eight feet (8 ft.). No side yards shall be required for a row building containing one (1) or two (2) dwelling units.
Except as provided in Subtitle F § 306.1, the following side yard rules apply:
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A side yard shall not be required along a side street abutting a corner lot in an RA-1, RA-2, RA-3, RA-4, and RA-5 zone.
Existing conforming side yards may not be reduced to a nonconforming width or eliminated.
In the case of a building with a non-conforming side yard, an extension or addition may be made to the building; provided, that the width of the existing side yard shall not be reduced or eliminated; and provided further, that the width of the side yard adjacent to the extension or addition shall be a minimum of three feet (3 ft.).
D.C. Mun. Regs. tit. 11, r. 11-F306