Substantial Improvement Date

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A substantially improved building is a building that has undergone reconstruction, rehabilitation, addition, or other improvement, the cost of which equals or exceeds 50 percent (or a lower threshold if adopted and enforced by the community) of the market value of the building before the “start of construction” of the improvement.

This term does not include a building that has undergone reconstruction, rehabilitation, addition, or other improvement related to:

• Any project or improvement of a building to correct existing violations of a state or local health, sanitary, or safety code specifications that have been identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions;

• Any alteration of a “historic building”, provided that the alteration will not preclude the structure’s continued designation as a “historic building.”

Note: All historic buildings are Pre-FIRM construction if they meet the definitions of a "historic building” provided they meet the NFIP definition.

When a building has been substantially improved, the agent must confirm if a local community official has declared the building substantially improved. The Application Form must report both the original date of construction and the substantial improvement date.

The NFIP will use the substantial improvement date for policy coverage and rating purposes.

This page contains information about the NFIP. Find more NFIP Resources.