Within any residential zoning district, any fence or wall shall not exceed five feet in height within a rear or side yard of a residential lot less than 10,000 square feet in area and shall not exceed a height of six feet within a rear or side yard of a residential lot 10,000 square feet in area or larger. Moreover, on any corner residential lot with two front yards, a fence or wall shall be permitted in one of the front yards in accordance with the provisions specified in Subsection 20-4.4c(15)(vi) hereinbelow;