No building shall hereafter be erected or structurally altered unless the following yards are provided and maintained in connection with such building:
A. Front Yard: On every zoning lot a front yard of not less than twenty five feet (25') in depth shall be provided. However, where lots within the same block and comprising forty percent (40%) of the frontage on the same street are already developed on the effective date of this Title with front yards with an average depth of less than twenty five feet (25'), then such average depth shall be the required front yard depth for such frontage in said block.
B. Side Yards: On every zoning lot a side yard shall be provided along each side lot line. Each side yard shall be not less in width than ten percent (10%) of the lot width, but need not exceed twenty feet (20') in width. (Ord. B-39, 1969)