FEMA flood zone rules in Honolulu County, HI — also called floodplain regulations or special flood hazard area (SFHA) rules — determine flood insurance requirements and elevation standards for new construction.
ROH Chapter 21A applies FEMA flood insurance rate maps to Oahu and requires development in special flood hazard areas to elevate to or above base flood elevation, with variances available only under strict Sec. 21A-1.12 standards.
Chapter 21A is Honolulu County's floodplain ordinance, adopting FEMA FIRMs under Sec. 21A-1.5 to define special flood hazard areas across Oahu, including Mapunapuna, Kakaako makai, Waikiki fringes, and low-lying windward streams. Sec. 21A-1.8 sets flood fringe standards requiring new construction and substantial improvements to be elevated to or above the base flood elevation, with dry floodproofing permitted for non-residential structures. Sec. 21A-1.12 governs variances, which are narrowly granted. LUO Sec. 21-9.10 cross-references flood hazard compliance for land use permits.
Construction below BFE without approval can result in notices of violation, loss of NFIP insurance eligibility for the structure, daily civil fines, and required elevation or removal of non-conforming improvements.
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See how Honolulu County's flood zones rules stack up against other locations.
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