Kauai County, HI Environmental Rules: Flood Elevation Requirements (2026)

Section 15-1.5, Construction and Development Standards, is part of Kaua'i County Code Chapter 15, Article 1, Floodplain Management, the county's local floodplain ordinance implementing the National Flood Insurance Program. Subsection (a) covers the flood fringe areas mapped as AE, AO and AH zones on the community's Flood Insurance Rate Map. Within (a)(3)(A), Residential Structures, new construction, repetitive loss structures and substantial improvements of residential buildings in A1-30, AE, AO and AH zones must have the lowest floor, including any basement, elevated to or above the base flood level; any fully enclosed area below that lowest floor used only for parking, building access or storage must include openings sized to automatically equalize hydrostatic flood forces on the walls by letting floodwater enter and exit.

Subsection (a)(3)(C) sets a stricter number for manufactured homes: they must sit on a permanent foundation with the lowest floor elevated to or above the base flood elevation plus one foot, and the enclosed space below is likewise limited to parking, access or storage. Nonresidential buildings in the same zones under (a)(3)(B) may instead be dry-floodproofed to be watertight below the base flood level. A registered professional engineer or architect must certify compliance before a certificate of occupancy is issued, and the County Engineer administers the floodplain ordinance and reviews the FIRM data used to set each parcel's base flood elevation.