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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 and checklist 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.
2. Verify the cost of repairs to the structure.
3. Verify the market value of the structure.
4. Make the SD determination and issue it to the property owner.
5. Permit development/ensure compliance with community ordinance.
6. Maintain documentation.

Connections with Flood Insurance and FEMA Grants