(a) Front Yard Exception. When a vacant lot is situated between two improved lots, each having a principal building within twenty-five feet of any side lot line of such unimproved lot, and when both such improved lots contain principal structures which do not conform with the minimum front yard setbacks in that district, the front yard requirements of the unimproved lot may be reduced to the greater of the two front yard setbacks of the adjoining improved lots, but in no case shall be less than ten feet.
(b) Additional Yards Required Where C and M Uses Abut R Districts. All uses permitted in C or M districts, which abut at the lot line or on the same street an R zone, shall provide yards, where they abut, at least the minimum yard requirements in accordance with such R districts. (1977 Code Title 4A.)