The lawful use of any land or a building or structure or a part thereof existing at the time that this chapter or any amendment thereto becomes effective may be continued although such use does not conform with the provisions of this chapter, except as otherwise provided in this Article
XIV.
No nonconforming use shall be changed to other than a conforming
use for the district in which it is situated.
The limitations of §
120-75 shall not apply to a building or other structure utilized as a dwelling which is nonconforming only in respect to yard space or area per dwelling and nonconforming to the district in which it is located, except that no dwelling building shall be altered, added to or reconstructed to extend further into an already deficient yard space or to reduce an already deficient amount of land area per dwelling.