Urban Honolulu Hurricane Preparedness: Flood Elevation Rules (2026)

Flood elevation in the City and County of Honolulu is regulated through ROH Chapter 21A (Flood Hazard Areas) in compliance with the National Flood Insurance Program. FEMA Flood Insurance Rate Maps (FIRMs) designate Special Flood Hazard Areas across Oahu, including riverine AE zones along streams such as Manoa, Nuuanu, Kalihi, and Palolo, and coastal VE zones along north shore beaches, windward bays, and some south shore locations. In AE zones, the lowest floor (including basement) of new and substantially improved residential structures must be elevated to or above the BFE plus one foot of freeboard. In VE zones, the lowest horizontal structural member of the lowest floor must be elevated above the BFE plus freeboard, and the structure must be on piles or columns designed to resist wave action, with no obstructions below (breakaway walls only). Enclosures below the BFE may only be used for parking, storage, or building access, must be flood-vented in A zones, and must be breakaway in V zones. Mechanical, electrical, and plumbing equipment must be elevated above the flood elevation. Tsunami inundation zones are mapped separately by Hawaii Civil Defense — while not regulated through the NFIP, they inform prudent construction practices. SMA permits under HRS 205A are required for coastal construction, with additional shoreline setback requirements. Elevation certificates are required at construction and help determine flood insurance rates.