The City of Key West, Florida

The Southernmost City in the Continental United States

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Substantial Improvement (50% Rule)

What Does the Term "Substantial Improvement" Mean

Older buildings - built prior to Dec. 31, 1974 -  were grandfathered into the flood insurance program at their current heights. 

That grandfathered status expires once the building has been Substantially Improved; which means repaired or remodeled to 50% or more of the building's market value. 

  • Important points:
    • Only the building's value, not the value of the entire property, is considered.
    • If a lot has multiple buildings, then only the value for the building being renovated is considered.
    • The 50% threshold is determined by the cumulative value of work performed during the past five years.

Once the Substantial Improvement threshold has been, or will be reached, it usually requires the building be elevated to current height requirements above flood levels.

Important Note:  Each building needs its own Building Permit Application, even if they're on the same lot.  Only one set of plans is needed, not a set for each application. 

Check out sub-topics (left) under Substantial Improvement for more information.

Substantial Improvement FAQ

Historic Building Exemption

Substantial Improvement Forms & Publications

City Procedure for Substantial Improvement/Damage Determinations

Contact Us

Scott Fraser,
FEMA Coordinator/Floodplain Administrator
Building Department
1300 White St
Key West, FL 33040
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  • Tuesday, 9:00 a.m. - 5:00 p.m. Wednesday, Noon - 5:00 p.m. Thursday, 9:00 a.m. - 5:00 p.m.

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