Lot Coverage Limits: Mililani Town vs Waipahu
How do lot coverage limits rules compare between Mililani Town, HI and Waipahu, HI?
Waipahu has fewer restrictions than Mililani Town.
Mililani Town, HI
Honolulu County
Mililani Town residential lots follow ROH Sec. 21-3.70-1 impervious caps. Homes permitted after May 1, 2019 are limited to 75 percent impervious coverage, with HOAs often requiring additional landscaped area.
View full Mililani Town 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 | Mililani Town | 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.
Mililani Town FAQ
Can I extend my driveway to fit an extra vehicle?
Possibly, but confirm total impervious coverage stays under 75 percent and HOA approves the revised frontage design.
Does a covered lanai count as impervious?
Yes, roofed lanais typically count as impervious for coverage calculations, even if the floor is open slab or deck.
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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