Hamilton County, TN Environmental Rules: Flood Elevation Requirements (2026)

Hamilton County's Flood Hazard Regulations (Zoning Regulations Art. V, Section 500, most recently amended by Resolution 825-27 on August 20, 2025) apply to all areas within the unincorporated county; incorporated cities like Chattanooga administer their own floodplain rules. 1 sets the elevation floor for residential construction: in AE Zones where FEMA has published a Base Flood Elevation, the lowest floor, including any basement, must be elevated to no lower than one foot above that BFE. This one-foot add-on is defined in Article V as the Regulatory Flood Protection Elevation, the BFE plus a mandatory one-foot freeboard.

Where a property sits in an approximate A Zone with no established BFE and no alternative data available, the Floodplain Administrator instead requires the lowest floor to be elevated at least three feet above the highest adjacent grade, using the grade definition in Article II. 2, but may floodproof in lieu of elevating if a Tennessee registered professional engineer or architect certifies the design meets the county's watertight and structural-load standards. Builders who elevate on solid perimeter foundation walls must add openings sized to equalize hydrostatic pressure on both sides of the walls, per the Enclosures standard referenced in the same subsection. A Finished Construction Elevation Certificate, verifying the as-built lowest-floor elevation, is required before the county will issue a Certificate of Compliance or Occupancy.