All buildings to be constructed, altered or moved in the C-2 district shall meet the following minimum requirements:

A. Front yard - no minimum yard required except that on lots used exclusively for residential purposes, the front yard requirement imposed in the R-2 residential district shall apply;

B. Side yard - no minimum yard required, except lots adjoining a residential district must provide a minimum side yard of ten feet. The side yard shall be increased five feet for every five feet, or fraction thereof, of building height over thirty feet. In any event, on lots used exclusively for residential purposes the side yard requirement imposed in the R-2 residential district shall apply;

C. Rear yard - twenty feet. Where a rear lot line abuts an alley, one-half of the width of such alley may be considered in meeting the rear yard requirements. In any event, on lots used exclusively for residential purposes, the rear yard requirement imposed in the R-2 residential district shall apply. (Zoning ordinance dated 6/3/03 § 8-6.0)