Yard requirements specified elsewhere in this chapter shall be subject to the following exceptions and modifications:
(1) Side yard width may be varied where the side wall of a residence is not parallel with the side lot line or is broken or otherwise irregular. In such case the average width of the side yard shall not be less than the otherwise required least width; provided, however, that such side yard shall not be less at any point than one-half the otherwise required least width.
(2) Width of one side yard may be reduced when authorized by the zoning administrator to a width not less than three feet, provided the sum of the widths of the two side yards is not less than the required minimum and further provided the distance between the proposed dwelling and another dwelling, existing or proposed, on an adjacent lot is not less than that required elsewhere in this chapter.
Such reduction may be authorized only when the zoning administrator finds it to be warranted by the location of existing buildings or conducive to the desirable development of two or more lots.
(3) Industrial zone side yards may be utilized for railroad spurs except when the side yard adjoins a residential or commercial zone.
(4) Second story additions to single-family and/or two-family residences in the R-1, R-2, N-P, and R-M zones may be constructed with five-foot side yard setback if the second story addition is constructed five years or more after the date of original construction and approval is obtained from the city zoning administrator.
(5) For a single-family dwelling located on a corner lot in a residential zone the required rear yard area may be relocated to the side of the lot opposite the street side yard. Such substituted rear yard need not be twenty feet deep at all points provided that said yard area is at least five feet deep along the entire property boundaries and provided that within said yard a rectangle bounded by the interior side lot line, the rear lot line and the points of nearest sides of the main building contains at least as many square feet of yard area as the yard area which would be provided by a twenty-foot rear yard across the entire width of the parcel. No structure shall be located within the substituted rear yard except as provided by Section 25-21-10.
(6) Front yard setbacks shall be twenty feet in the commercial and industrial zones except in blocks where fifty percent or more of the block is developed and has lesser setbacks. In those blocks the setbacks shall be average of the two nearest buildings on the same side of the street. (Amended during the March 2009 supplement.)