(a)   No accessory building or structure constructed on any lot prior to the time of construction of the principal building to which it is accessory shall be used for living purposes; shall occupy more than 50 percent of the area of a required yard; or shall exceed the height of the principal building or structure.
   (b)   On a reversed corner lot in a Residence District, and within 15 feet of any adjacent property to the rear in a Residence District, no accessory building or portion thereof located in a required rear yard shall be closer to the side lot line abutting the street than a distance equal to two-thirds (2/3) the least depth which would be required under this Ordinance for the front yard on such adjacent property to the rear. Further, in the above instance, no such accessory buildings shall be located within five (5) feet of any part of a rear lot line which coincides with the side lot line or portion thereof of property in any Residence District.
   No accessory building shall be erected in or encroach upon the required side yard of a corner lot which is adjacent to the street, nor upon the required side yard of a reversed corner lot which is adjacent to the street.