A.
No use or occupancy of any building, structure or land shall hereafter be changed to a different use or occupancy and no building or structure or part thereof shall hereafter be erected, constructed, reconstructed, moved or structurally altered unless in conformity with all of the regulations herein specified for the district in which it is located, except as hereinafter provided.
B.
No lot in any zoning district shall have located upon it more than one principal structure or use, except as otherwise permitted herein this chapter.