Between a building line, as herein established, and the street line no building or portion of a building other than an unenclosed porch may be erected. In a Class I Residential, Class II Residential or Class III Residential District, building lines shall be established as follows:
(A) On property fronting on any street, a line which is back of the street line a distance equal to twenty percent of the average or normal depth of the lot, provided such distance is not less than thirty feet, shall be the building line for such street frontage. When in any portion of such street frontage there are lots of markedly less depth than the normal, the Board of Adjustment, in defining and applying the front yard line regulation established herein, may, when in its opinion the general purpose and intent of this section will be better served thereby, divide such street frontage into sections for the application of the above twenty percent building line requirement.
(B) Building lines shall be based on existing alignment in the following cases:
(1) On property fronting upon any street where twenty-five percent or more of such frontage on the respective side of the street is improved with residences between two adjacent streets, the average distance back from the street line of the houses already built in such square shall be the building line instead of the thirty feet herein established.
(2) On property fronting upon any street where sixty percent or more of such frontage between two adjacent streets is improved with buildings that are built at the street line, the street shall be the building line for that square.
(C) On property abutting two intersecting streets, the front yard shall be the yard serving as the principal means of access to the respective residences. In cases of connected residences having principal access from both streets, there shall be front yards upon both streets, and each building line shall be distant from its respective street line twenty percent of the lot dimension as measured from the respective street line or as otherwise specified herein. In cases where corner lots are developed with more than one residence building, the buildings, other than the one bordered by both streets, shall each have building lines distant from their front street lines twenty percent of the lot dimensions from such street lines, provided that buildings upon corner lots shall conform to the alignment of building or yard lines on adjacent lots which have similar direction of principal dimension in the original plat.
(1956 Code Sec. 1319.08)