ROH §21-9.10
Flood hazard area development rules
Read the official text at honolulu.gov ↗This section says permit applications must be checked against flood hazard rules before other approvals. In certain zones, homes can be built up to 5 feet taller if needed to meet flood elevation, but not more than 25 feet above base flood level. In a floodway, only two homes are allowed on one lot.
developershomeownerslandlords
The ordinance, as written (Honolulu County) — Developments in flood hazard areas
A copy, taken August 22, 2026. The version published by Honolulu is the one that governs, and it may have changed since. Check it before relying on anything here.
(a) All permit applications subject to this chapter must, at the time of processing, be reviewed for compliance with Chapter 21A. Whenever applicable, the flood hazard area requirements of a development project must be determined before processing for other approvals mandated by other laws and regulations.
(b) Dwellings in country, residential, and agricultural zoning districts, as well as single-unit, two-unit, and duplex-unit dwellings in apartment and apartment mixed-use zoning districts, may exceed the maximum height in the district by no more than 5 feet if required to have its lowest floor elevated to or above the base flood elevation; provided that such additional height must not be greater than 25 feet above the base flood elevation.
(c) Notwithstanding any other provision to the contrary, no more than two dwelling units are permitted on a single zoning lot whose only buildable area is in the floodway. This provision, designed to reduce flood losses, takes precedence over any less restrictive, conflicting laws, ordinances, or rules.
Published by the City and County of Honolulu through American Legal Publishing.
LawTrove is not legal advice. The summary above is a computer-generated restatement — the authoritative text is the official version linked above.