Flood Zones: Honolulu vs Waipahu
How do flood zones rules compare between Honolulu, HI and Waipahu, HI?
Honolulu and Waipahu have similar restriction levels.
Honolulu, HI
Honolulu County
Honolulu enforces FEMA flood zone construction standards under ROH chapter 21A and uses the city's Sea Level Rise Vulnerability Viewer to guide permits in low-lying coastal neighborhoods.
View full 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 | Honolulu | Waipahu |
|---|---|---|
| Local code | ROH Chapter 21A | - |
| Substantial improvement | 50 percent of value | - |
| Required document | Elevation Certificate | - |
| Map source | FEMA plus state SLR viewer | - |
| Permit agency | Honolulu DPP | - |
| - | - |
Highlighted rows indicate differences between cities.
Honolulu FAQ
How do I check if my Oahu property is in a flood zone?
Use the city's online flood hazard map and the State of Hawaii Sea Level Rise Viewer. DPP can also issue a written flood zone determination based on the current FEMA panels.
Does sea level rise affect my permit today?
Honolulu has begun incorporating sea level rise data into shoreline setback and SMA reviews, and freeboard above base flood elevation is strongly encouraged for new oceanfront construction.
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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