Within any residence district, except the RCD District, a front yard is required on every lot, which shall be of a mean depth of not less than 20 feet.

If on one side of a street within a given block there is pronounced uniformity of alignment of the fronts of existing buildings and of depths of front yards greater than the depths herein specified, a front yard shall be required in connection with any new building which shall conform as nearly as practicable to those provided on the adjacent lots, except that no such building shall be required to set back from the street a distance greater than 40 feet.

If on one side of a street within a given block there is pronounced uniformity of alignment of the fronts of existing buildings less than herein specified, the Board of Appeals may, upon application in any individual case, permit a reduction of the front yard depths hereinbefore specified in this section, for the purpose of preserving said uniformity of alignment.