No frame building shall be erected or maintained upon the same lot with a dwelling converted after April twenty-eighth, nineteen hundred thirty, nor shall any frame building not occupied on April thirteenth, nineteen hundred forty, as a multiple dwelling be altered or converted to such use; except that if the walls of a frame converted dwelling are faced with a veneer of brick and the entrance story is occupied by not more than one family, such entrance story may be altered so that it may be occupied by two families.
New York Legal Code