Structures located in the floodplain or floodway are subject to additional building regulations designed to protect not only the structure but also the floodplain. If you are contemplating a modification to your existing home, contact the Village before starting your design so that you understand the regulations before you get too far along in the process. Please remember that any modification to a structure in the floodplain may require a permit.
Substantial Improvement Rule
You may be able to construct an addition to a structure in the floodplain. In general, the cost of the addition must be less than 51% of the value of the structure itself. This regulation is known as the Substantial Improvement Rule (Municipal Code Title 22: Chapter 22.06.690). It is designed to limit the exposure of damage to structures in the floodplain. If the cost of the proposed addition would exceed the 50% threshold, then the entire structure must be brought into compliance with the floodplain regulations.
Expanding the Existing Area Footprint
Additions to structures in the floodplain may be located above the existing footprint or may expand the footprint of the structure. If the footprint is expanded, the additional area must comply with the floodplain requirements, which typically requires that the addition be elevated. You may not expand the footprint of structures in the floodway.
For more information, contact Kyle Goetzelmann, P.E., Civil Engineer II, at 847-499-9053.