No building or structure shall be constructed or enlarged unless the following yards are provided and maintained in connection with such buildings.

A. Front yard. A front yard of thirty (30) feet shall be required when all frontage between two (2) intersecting streets lies within this district. However, when lots within this district are adjacent to and adjoining lots in an R district, all of which front on the same street between two (2) intersecting streets, there shall be established the same front yard setback as has been established in the abutting R district or twenty (20) feet, whichever is more.

B. Side Yard. No side yard shall be required except for a lot which abuts an R district, or for a corner lot which abuts an R district, or upon an alley separating this district from an R district. There shall then be provided a side yard equal to one-half (½) the front yard required in the abutting R district, but in no case, less than fifteen (15) feet. The same setback shall apply also if business buildings front the intersecting street, commonly referred to as the side street.

C. Rear Yard. There shall be a rear yard of not less than twenty-five (25) feet; provided, however, that a one-story accessory building may be located thereon, except for the five (5) feet adjacent and parallel to the rear lot line or alley for the storage of motor vehicles and the unloading of vehicles under roof.