The required side yard setback shall be zero (0) feet provided that the lot line does not abut a residential district in which case the minimum side yard requirement shall be fifteen (15) feet unless a public street intervenes in which case the front yard requirement of five (5) foot setback shall govern. There shall be no deviation from this zero (0) foot dimension without an application for a variance to the Zoning Board of Adjustment or Planning Board, whichever has jurisdiction, for relief from this requirement. Where due to building orientation, lot configuration or other condition that preclude entry to the rear of a property for parking area access, loading/unloading, refuse collection, public safety vehicle access or any other purpose requiring such entry, a paved alleyway no wider than fifteen (15) feet shall be permitted alongside or within the frontage of the building. In such cases where the building has more than one (1) story, all additional stories shall be constructed pursuant to governing building codes above said alleyway with the aforementioned side yard requirements where applicable.