In any district in which one-family dwellings are permitted, a one-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. Such lot must be in separate ownership and not of continuous frontage with other lots in the same ownership. 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 requirements other than those applying to area or width, or both, of the lot shall conform to the regulations for the district in which the lot is located provided it meets Health Department standards. Variances of yard requirements shall be obtained only through action of the Board of Zoning Appeals.