A lawful nonconforming structure existing at
the time of the adoption or amendment of this chapter may be continued
although its size or location does not conform to the lot width, lot
area, yard, height, parking and loading, and access provisions of
this chapter. However, it shall not be extended, enlarged, reconstructed,
moved or structurally altered except when required to do so by law
or order or so as to comply with the provisions of this chapter.
Once a nonconforming use or structure has been
changed to conform, it shall not revert back to a nonconforming use
or structure. Once the Board of Adjustment has permitted the substitution
of a more restrictive nonconforming use for an existing nonconforming
use, the substituted use shall lose its status as a legal nonconforming
use and become subject to all the conditions required by the Board
of Adjustment.
Additions in the street yard of existing structures
shall not project beyond the average of the existing street yards
on the abutting lots or parcels.
The required street yard, or setback, may be
decreased in any residential district to the average of the existing
street yards of the abutting structures on each side but shall in
no case be less than 15 feet.