Lot Coverage Limits: Kailua vs Waipahu
How do lot coverage limits rules compare between Kailua, HI and Waipahu, HI?
Waipahu has fewer restrictions than Kailua.
Kailua, HI
Honolulu County
Kailua residential lots follow ROH Sec. 21-3.70-1, which limits impervious surface coverage. Homes permitted after May 1, 2019 are capped at 75 percent impervious coverage to reduce runoff and protect windward watersheds.
View full Kailua rules →Waipahu, HI
Honolulu County
Waipahu lot coverage follows ROH 21-3.70-1, capping impervious surface at 75 percent for dwellings permitted after May 1, 2019, straining tight plantation and multi-generational lots.
View full Waipahu rules →Key Facts Comparison
| Fact | Kailua | Waipahu |
|---|---|---|
| - | - | |
| Impervious cap | - | 75 percent |
| Effective date | - | May 1, 2019 |
| Code section | - | ROH 21-3.70-1 |
| Stream overlay | - | Chapter 14 drainage |
Highlighted rows indicate differences between cities.
Kailua FAQ
Does a gravel driveway count against coverage?
Gravel is generally treated as pervious, helping stay under the 75 percent cap, though compacted surfaces may count differently.
What if my existing home already exceeds 75 percent?
Older lots may be grandfathered, but any major expansion or rebuild will typically require compliance with current caps.
Waipahu FAQ
What is the Waipahu impervious limit?
Dwellings permitted after May 1, 2019 cap impervious surface at 75 percent of the lot under ROH 21-3.70-1. Driveways, patios, and pool decks all count toward the limit on narrow plantation lots.
Do older Waipahu homes need to comply?
Pre-2019 homes exceeding the 75 percent cap are typically legally nonconforming. Substantial redevelopment, demolition, or expansion triggers full compliance with the current ROH 21-3.70-1 impervious cap.
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