The provisions of this chapter do not require any changes or improvements to be made to lawfully existing structures. However, when an improvement is made to any existing structure, the provisions of § 220-31 shall apply.
The following provisions shall apply whenever any improvement is made to an existing structure located within any identified floodplain area:
A. 
No expansion or enlargement of an existing structure shall be allowed within any floodway area that would cause any increase of the base flood elevation.
B. 
No expansion or enlargement of an existing structure shall be allowed within any special floodplain area that would, together with all other existing and anticipated development, increase the base flood elevation more than one foot at any point.
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 constitute a substantial improvement and shall be undertaken only in full compliance with the provisions of this chapter.
D. 
The above activity shall also address the requirements of the 34 Pa. Code, as amended, and the 2009 International Building Code and the 2009 International Residential Code.
E. 
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.