In any district in which single- family dwellings are permitted, 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 this chapter, notwithstanding limitations imposed by other provisions of the chapter. This provision shall apply even though such lot fails to meet the requirements for area or width, or both, if the lot shall conform to the other bulk regulations for the district in which such lot is located. Variance of yard requirements shall be obtained only through the action of the Zoning Board of Adjustment.