Lot Coverage Limits: Urban Honolulu vs Waipahu
How do lot coverage limits rules compare between Urban Honolulu, HI and Waipahu, HI?
Urban Honolulu and Waipahu have similar restriction levels.
Urban Honolulu, HI
Honolulu County
Urban Honolulu caps impervious surface at 75 percent of lot area for residential dwellings permitted after May 1, 2019, under ROH 21-3.70-1 to manage runoff into the city's storm drains.
View full Urban Honolulu 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 | Urban Honolulu | Waipahu |
|---|---|---|
| Impervious cap | 75 percent | 75 percent |
| Effective date | May 1, 2019 | May 1, 2019 |
| Code section | ROH 21-3.70-1 | ROH 21-3.70-1 |
| Flood concern | Ala Wai drainage | - |
| Stream overlay | - | Chapter 14 drainage |
Highlighted rows indicate differences between cities.
Urban Honolulu FAQ
How much of an Urban Honolulu lot can be paved?
For residential dwellings permitted after May 1, 2019, ROH 21-3.70-1 limits impervious coverage to 75 percent. Older homes follow the standards in effect when they were permitted.
Do pool decks count toward Honolulu lot coverage?
Generally yes. Pool decks, patios, driveways, and roofed accessory structures count toward the 75 percent impervious cap under ROH 21-3.70-1. Pervious pavers with approved drainage can earn partial credit.
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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