Where can I find information on Substantial Damage and Substantial Improvements?

Information regarding Substantial Damage and Substantial Improvements can be found in FEMA P-758, Substantial Improvement/Substantial Damage Desk Reference (FEMA, 2010). To participate in the National Flood Insurance Program (NFIP), communities must adopt and enforce regulations and codes that apply to new development in Special Flood Hazard Areas (SFHAs). Local floodplain management regulations and codes contain minimum NFIP requirements that apply not only to new structures but also to existing structures that have been Substantially Damaged or which are undergoing Substantial Improvement. FEMA P-758 provides practical guidance and suggested procedures to implement the NFIP requirements for Substantial Improvement/Substantial Damage.

In addition, FEMA has an NFIP Policy Index available online with basic information about Substantial Improvement, and Substantial Damage.

Definition: Substantial Damage means damage of any origin for which the cost of restoring the structure to its before-damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred (FEMA, 2010).

Definition: Substantial Improvement means any reconstruction, rehabilitation, addition, or other improvement of a structure for which the cost of the work equals or exceeds 50 percent of the market value of the structure before the start of construction of the improvement. This term includes structures that have incurred “substantial damage” regardless of the actual repair work performed (FEMA, 2010).

References: FEMA. 2010. Substantial Improvement/Substantial Damage Desk Reference. FEMA P-758. Washington, DC. May 2010.

Last updated November 16, 2021