FEMA Standards for Substantial Improvement / Substantial Damage Determinations

FEMA, 2010. Substantial Improvement / Substantial Damage Desk Reference, Federal Emergency Management Agency, Washington, DC

When buildings undergo repair or improvement, it is an opportunity for local floodplain
management programs to reduce flood damage to existing structures. More than 21,000 communities
participate in the National Flood Insurance Program (NFIP), which is managed by
the Federal Emergency Management Agency (FEMA). To participate in the 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 which
are “substantially improved (SI)” or “substantially damaged (SD).”
Enforcing the SI/SD requirements is a very important part of a community’s floodplain management
responsibilities. There are many factors that local officials will need to consider and
several scenarios they may encounter while implementing the SI/SD requirements. This Desk
Reference provides practical guidance and suggested procedures to implement the NFIP requirements
for SI/SD.
This Desk Reference provides guidance on the minimum requirements of the NFIP regulations.
State or locally-adopted requirements that are more restrictive take precedence (often referred
to as “exceeding the NFIP minimums” or “higher standards”).