Any lot legally held in separate ownership at the time of adoption of this title, which lot is below the requirements for lot area or lot width or frontage for the district in which it is located and on which lot a dwelling would be permitted if the lot met the area requirements of this title, may be used for a single-family dwelling if such a lot is located in a residential district. The width of each of the side yards for such a dwelling may be reduced to a width which is not less than the same percentage of the lot width as the required side yard would be of the required lot width; provided, that in no case shall the smaller of the two (2) yards be less than five feet (5'), nor shall the total width of the two (2) yards be less than thirteen feet (13'); provided, however, that when this title replaces a previously adopted zoning ordinance, if a lot was legally created under the provisions of that ordinance, it shall be classified as a legal nonconforming lot under this title. (Ord. 93-5, 7-6-1993, eff. 7-15-1993)