The plot, tract or lot faces upon a dedicated street and was separately owned prior to December 28, 1971, or prior to annexation to the City of Odessa and the boundaries of which have not been changed even though the ownership may have changed, whichever is applicable, and no main building exists on the plot, tract or lot, in which event a building permit for only one main building may be issued on each such original separately owned parcel without first complying with subsections 14-12-1(1) and 14-12-1(2) of this section.