Substantial Improvement / Substantial Damage Rule

The rule states that if the cost of improvements or the cost to repair the damage, or when the cumulative value of improvements exceed 50 percent of the market value of the build, then the structure must be elevated and brought up to current floodplain compliance. The SI/SD requirements grew out of the recognition that there were large numbers of buildings and manufactured homes already located in floodprone areas before communities joined the National Flood Insurance Program (NFIP).

The 50 percent threshold was chosen as a compromise between two extremes. One extreme would be to prohibit all investment in existing structures that do not meet minimum NFIP requirements. The other extreme would be to allow structures in flood hazard areas to be improved in any fashion without regard to the flood risk. The threshold of 50 percent is a compromise at a half-way point and was chosen because it conforms to similar building code and zoning standards that also use this threshold.

If work on buildings constitutes SI/SD, then structures must be brought into Yavapai Counties floodplain compliance including the requirement that lowest floors be elevated to or above the base flood elevation (BFE). Meeting this requirement can also be accomplished by demolition followed by construction of new buildings that meet the NFIP requirements on the same sites or by relocating buildings to locations outside of the SFHA.

For more information: FEMA 213 Answers to Questions About Substantially Improved/Substantially Damaged Buildings
https://www.fema.gov/sites/default/files/2020-07/fema_p213_08232018.pdf 

Yavapai County Summary of Requirements for Construction in a Special Flood Hazard Area(DOC, 134KB)