In any district in which single-family dwellings are permitted, notwithstanding limitations imposed by other provisions of this chapter, a single-family dwelling and customary accessory buildings may be erected on any single lot of record at the effective date of adoption or amendment of the ordinance codified in this chapter. This provision shall apply even though such lot fails to meet the requirements for area or width or both that are generally applicable in the district, provided that yard dimensions and other requirements not involving area or width of the lot, or both, shall conform to the regulations for the district in which such lot is located. Variance of area, width, and yard requirements shall be obtained only through action of the Board of Adjustment.