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

Noblesville's floodplain regulations sit inside the Unified Development Code's Flood Hazard (FH) District, § 159.109(A), which the Common Council adopted under I.C. 36-1-4-11 to reduce flood losses in the mapped Special Flood Hazard Areas (SFHAs) shown on the FEMA Flood Insurance Rate Map for Hamilton County. The code does not simply require building to the base flood elevation; § 159.016 defines the Flood Protection Grade (FPG) as the base flood elevation plus a two-foot freeboard margin, and that FPG, not the bare BFE, is the compliance line.

Section 159.109(A)(14) applies this to residential construction: for new construction or a substantial improvement (excluding manufactured homes) located in Zone A or Zone AE, the lowest floor of the structure, including any basement, must sit at or above the FPG. A residential structure may instead be built on permanent fill or a stem-wall foundation if it meets the section's engineering criteria, and any fully enclosed area below the FPG must be designed to preclude finished living space and to admit floodwater automatically so it doesn't build up hydrostatic pressure on the walls.

Non-residential structures get an alternative under § 159.109(A): they can be elevated to the FPG or floodproofed to the FPG instead, certified by a registered engineer or architect. 'Substantial improvement' is triggered whenever addition or repair costs reach 40% of the structure's market value, and the same standard applies to a repetitive-loss structure. The Floodplain Administrator, a role within Planning and Development, reviews permits and certifications for compliance in the SFHA.