Flood Zones: Urban Honolulu vs Waipahu
How do flood zones rules compare between Urban Honolulu, HI and Waipahu, HI?
Urban Honolulu and Waipahu have similar restriction levels.
Urban Honolulu, HI
Honolulu County
Urban Honolulu's Mapunapuna, Waikiki fringe, and Kakaako makai properties lie in FEMA special flood hazard areas adopted under ROH Sec. 21A-1.5, with elevation and floodproofing required under Sec. 21A-1.8.
View full Urban Honolulu rules →Waipahu, HI
Honolulu County
Waipahu development in FEMA-mapped flood zones must comply with ROH Chapter 21A, covering special flood hazard areas, elevation standards, and flood variance procedures.
View full Waipahu rules →Key Facts Comparison
| Fact | Urban Honolulu | Waipahu |
|---|---|---|
| Authority | ROH Chapter 21A | - |
| Map source | FEMA FIRM | - |
| Elevation rule | Sec. 21A-1.8 | - |
| Variance | Sec. 21A-1.12 | - |
| Urban hot spots | Mapunapuna, Waikiki, Kakaako | - |
| - | - |
Highlighted rows indicate differences between cities.
Urban Honolulu FAQ
Is Mapunapuna really in a flood zone?
Yes. FEMA FIRMs adopted under Sec. 21A-1.5 place much of Mapunapuna in a special flood hazard area, with chronic tidal flooding driving elevation and floodproofing requirements.
Can a Waikiki tower project get a flood variance?
Only under Sec. 21A-1.12 hardship standards, which are narrowly applied. Urban Honolulu variances are rare, and denials preserve NFIP insurance rating for surrounding structures.
Waipahu FAQ
Is my Waipahu house in a flood zone?
Review the FEMA Flood Insurance Rate Maps adopted under Sec. 21A-1.5 through city GIS or the FEMA map portal to find your property's specific flood zone designation.
Can I finish my basement in a flood zone?
Finishing below base flood elevation is generally restricted. Enclosures below BFE must meet flood opening and material requirements under Sec. 21A-1.8, so check with permitting first.
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