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

Chapter 10 of the Sumner County Zoning Resolution governs construction in mapped Special Flood Hazard Areas of the unincorporated county (Gallatin, Hendersonville, Portland and White House enforce their own floodplain rules inside city limits). Under Section 1005, Subsection B, new construction and substantial improvement of any residential building or manufactured home in an AE Zone, where FEMA has published a Base Flood Elevation, must have its lowest floor, including any basement, elevated to no lower than three feet above that BFE. Non-residential buildings get a lower bar: one foot above BFE, achieved by elevation or by watertight flood-proofing with walls capable of resisting hydrostatic and hydrodynamic loads.

Where a lot sits in an approximate A Zone with no published BFE, the Floodplain Administrator, a role assigned to the County Engineer under Section 1004, Subsection A, instead requires the lowest floor at least three feet above the highest adjacent grade. Any elevated structure that relies on solid perimeter foundation walls must include flood vent openings sized to equalize hydrostatic pressure on both sides of the walls, per the Resolution's enclosure standards. Shallow-flooding Zone AO lots use a separate rule: the lowest floor must clear the FIRM's depth number by one foot of freeboard, or sit three feet above the highest adjacent grade if no depth number is shown. A Tennessee-licensed engineer's certification is required whenever fill or development narrows a stream's flood-carrying capacity.