§ 81-23
Continuation of existing structures. 

Structures existing in any identified floodplain 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 identified floodway area shall not be expanded 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 50% or more of its market value shall be undertaken only in full compliance with the provisions of this chapter.

C. 

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.