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Substantially Improved Building

A building that has undergone reconstruction, rehabilitation, addition, or other improvement, the cost of which equals or exceeds 50% 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:
1. 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; or
2. Any alteration of a "historic building", provided that the alteration will not preclude the structure's continued designation as a "historic building".

Glossary Section
NFIP - National Flood Insurance Program
Last updated March 5, 2020