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.
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:
- 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.
|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