R1 R2 R3 R4 R5 

In the districts indicated, where the width of a zoning lot is less than that required under the provisions of Section 23-11 (Lot Area and Lot Width Regulations in R1 Through R5 Districts), for a single- or two-family residence, the required total width of side yards, or minimum open area provided along a side lot line, as applicable, may be reduced by four inches for each foot by which the width of a zoning lot is less than that required, and where applicable, the minimum distance required between a residence on an adjacent zoning lot may be reduced by six inches for each foot by which the width of a zoning lot is less than that required, provided that the narrow lot condition was in existence on December 15, 1961, and, subsequently, such narrow lot condition has neither increased nor decreased in width.

However, in no event shall the required width of a side yard or open area be less than three feet and, where applicable, the minimum distance between a residence on an adjacent zoning lot be less than five feet.