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Making Substantial Damage (SD) Determinations

Information about making Substantial Damage Determinations for Existing Buildings in the Special Flood Hazard Area

Before repairs to buildings located in the Special Flood Hazard Area shown on FEMA’s flood maps can be performed, NFIP communities must determine if the building has been Substantially Damaged. This is a formal determination of whether the cost to repair a building to its “before damage” condition will equal or exceed 50% of the market value of the structure before the damage. This determination must be made for proposed repairs to damage from any source, not just flooding.

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

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

SD Resources

SD Determination Process for Community Officials

Listed below are general steps that must be performed by communities to make SD determinations. Your community’s process may vary depending on the number of buildings affected by damage. The NH Flood Hazards Handbook pdf file contains best practices for community officials making SD determinations following a significant disaster.

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

Connections with Flood Insurance and FEMA Grants

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Portable Document Format Symbol Portable Document Format (.pdf). Visit nh.gov for a list of free .pdf readers for a variety of operating systems.

NH Office of Strategic Initiatives