Flood Zones: Honolulu vs Mililani Mauka
How do flood zones rules compare between Honolulu, HI and Mililani Mauka, HI?
Mililani Mauka has fewer restrictions than Honolulu.
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 →Mililani Mauka, HI
Honolulu County
Most Mililani Mauka parcels sit on elevated terrain outside special flood hazard areas, but ROH Chapter 21A still governs any properties mapped within FEMA flood zones.
View full Mililani Mauka rules →Key Facts Comparison
| Fact | Honolulu | Mililani Mauka |
|---|---|---|
| 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.
Mililani Mauka FAQ
Is my Mililani Mauka home likely in a flood zone?
Most upland lots are in Zone X, but parcels near stream corridors can fall within mapped flood zones; verify using the FEMA FIRM or ask DPP.
What if my project is near a drainage easement?
Drainage easements often carry mapped flood zones, so Chapter 21A elevation and construction standards may apply to any new construction nearby.
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