Making Substantial Improvements (SI) Determinations

Information about making Substantial Improvement Determinations for Proposed Development in the Special Flood Hazard Area

Before improvements to buildings located in the Special Flood Hazard Area on FEMA flood maps can be performed, NFIP communities must determine if the building has been Substantially Improved. This is a formal determination of whether the cost of repairs and improvements will equal or exceed 50% of the market value of the structure before the improvement.

If proposed improvements are determined to be a Substantial Improvement (SI), the building must meet the same requirements in the community’s floodplain ordinance that apply for new construction. Communities may choose to adopt a higher standard (e.g., using a lower percentage to make the SI determination or adopting a cumulative SI provision) to further improve flood resilience in the community.

There are exceptions to the SI provision that apply for alterations of designated historic structures and corrections of existing code violations, as outlined in the community’s floodplain ordinance.
 

SI Resources

• More information about the SI provision, making SI determinations, and the exceptions above is available in FEMA’s Substantial Improvement (SI) /Substantial Damage (SD) Desk Reference.
• The NH Floodplain Management Team has developed the following resources:
  • “An Introduction to Substantial Improvements and Substantial Damage”, a half-hour training video for community officials.
  • The SI/SD Application Packet and Property Owner Guide to SI/SD which community officials can use to better manage the SI determination process.
• Other helpful resources include:
  • Making Substantial Improvement Determinations webinar (recording and slide deck )
  • Answers to Questions About Substantially Improved/Substantially Damaged Buildings (FEMA)
  • State Model Floodplain Ordinances and Menu of Higher Floodplain Regulation Standards
  • Guidance for Making Substantial Damage Determinations

SI Determination Process for Community Officials

The steps that must be performed by communities to make an SI determination include the following.
 

Community Officials SI Determination Process Step
Step	Resources
1. Review permit application to check if a Substantial Improvement determination needs to be made.	Substantial Improvement and Substantial Damage Application Packet Property Owner Guide to Understanding Substantial Improvement/Damage Requirements SI/SD Desk Reference (Sections 5.5 and 5.6)
2. Verify the cost of improvements to the structure.	Substantial Improvement and Substantial Damage Application Packet SI/SD Desk Reference (Section 4.4)
3. Verify the market value of the structure.	Substantial Improvement and Substantial Damage Application Packet SI/SD Desk Reference (Section 4.5)
4. Make the SI determination and issue it to the property owner.	SI/SD Desk Reference (Sections 4.3, 5.6.15, Appendix E)
5. Permit development/ensure compliance with community ordinance.	Your community’s floodplain ordinance SI/SD Desk Reference (Sections 5.6.12 and 5.6.13)
6. Maintain documentation.	Your community’s floodplain ordinance SI/SD Desk Reference (Section 5.6.14)