In any R-Residential District, notwithstanding limitations imposed by other provisions of this Ordinance, a single family dwelling may be erected on any single lot of record not less than sixty-six feet (66 ft.) In width, existing at the effective date of the adoption or amendment of this Ordinance, provided that yard requirements of the lot shall conform to the regulations for the district in which such lot is located. A variance shall not be required for a permit unless yard requirements are to be altered.