Side yard. There shall be two side yards, and no side yard shall be less than 20 feet. Parking as required shall be permitted in the side yard, provided the area is at no point closer than 10 feet to any adjoining street right-of-way. No parking area shall be nearer than 10 feet to any building excepting residential buildings nor five feet to any other property line; provided, however, that a parking area as herein permitted is allowed up to the side property line if it abuts a parking area on the adjacent lot. Adjoining a residence zone boundary line, the minimum parking lot separation shall be 20 feet and such separation area shall constitute a buffer zone.