Bloomington, IN Environmental Rules: Flood Elevation Requirements (2026)

Bloomington's floodplain ordinance builds in an extra safety margin above FEMA's mapped base flood elevation (BFE) before it will let anyone build. The code defines the 'Flood Protection Grade' (FPG) as the BFE plus two feet at any location in a special flood hazard area; in a Zone AO area with no mapped flood depth, two feet above the highest adjacent grade is used as the minimum instead. That two-foot cushion is what the code calls 'freeboard,' a factor of safety applied because actual flood heights can exceed what the calculated base flood predicts.

040(e)(4)(B)(ii) applies that definition directly to houses: in Zone A and Zone AE, new construction or a substantial improvement of a residential structure must have its lowest floor, including any basement, at or above the FPG, meaning two feet above the mapped base flood elevation, not merely level with it. A builder who elevates the house on solid foundation perimeter walls must also install flood openings sized to let floodwaters move through the enclosed space automatically, and a builder who uses fill to reach that elevation has to meet separate fill-compaction and slope standards elsewhere in the same section.

Zone AH and Zone AO carry their own versions of the same two-foot-above-flood-depth rule. Anyone building new or adding a substantial improvement in one of Bloomington's mapped flood zones should plan the lowest floor elevation around the FPG number the Floodplain Administrator provides, not just the raw FEMA base flood elevation.