A lot of record, or a lot in a subdivision of which the preliminary plan has been approved, which does not comply with the area or width of lot regulations of the district in which it is located on the effective date of the Zoning Code, or any amendment thereto, making the lot nonconforming, may be used as follows:
(a) If occupied by a building, the building may be maintained, repaired, modernized, or altered, provided, however, that the building may not be enlarged in floor area or converted to another use, unless the enlarged or converted areas comply with the yard regulations.
(b) If vacant, the lot may be used as a site for a one-family dwelling, provided that all regulations of the Zoning Code, except the lot area and lot width regulations, shall be complied with.
(1980 Code 151.24)