Structures existing in any identified flood-prone
area prior to the enactment of this chapter, but which are not in
compliance with these provisions, may continue to remain subject to
the following:
A. Existing structures located in any designated floodway
area shall not be expended or enlarged, unless the effect of the proposed
expansion or enlargement on flood heights is fully offset by accompanying
improvements.
B. Any modification, alteration, reconstruction, or improvement
of any kind to an existing structure, to an extent or amount of less
than 50% of its market value, shall be elevated and/or floodproofed
to the greatest extent possible.
C. Any modification, alteration, reconstruction, or improvement
of any kind to an existing structure, to an extent or amount of 50%
or more of its market value, shall be undertaken only in full compliance
with the provisions of this chapter.