Within the districts established by this chapter
and later amendments hereto, there exist nonconforming situations:
lots, buildings and structures, uses of land and uses of buildings
or structures and land in combination which were lawful before this
chapter was passed and amended, but which would be prohibited or restricted
under the terms of this chapter or future amendment. It is the intent
of this chapter to permit these nonconformities to continue until
they are removed, but not to encourage their survival. It is further
the intent of this chapter that nonconformities shall not be enlarged
upon, expanded or extended, except as hereinafter provided, nor be
used as grounds for adding other structures or uses prohibited elsewhere
in the same district.