Lot Coverage Limits: Honolulu vs Mililani Town
How do lot coverage limits rules compare between Honolulu, HI and Mililani Town, HI?
Honolulu has fewer restrictions than Mililani Town.
Honolulu, HI
Honolulu County
Honolulu County's LUO Section 21-3.70-1 caps impervious surface at 75 percent of lot area for residential dwellings permitted after May 1, 2019, to control runoff and preserve neighborhood character.
View full Honolulu rules →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 →Key Facts Comparison
| Fact | Honolulu | Mililani Town |
|---|---|---|
| Impervious cap | 75 percent | - |
| Effective date | May 1, 2019 | - |
| Code section | ROH 21-3.70-1 | - |
| Applies to | New residential dwellings | - |
| - | - |
Highlighted rows indicate differences between cities.
Honolulu FAQ
How much of my lot can I cover with buildings and pavement in Honolulu?
For residential dwellings permitted after May 1, 2019, ROH 21-3.70-1 caps impervious coverage at 75 percent of lot area. Older homes are subject to the standards in effect when permitted.
Do driveways count toward lot coverage?
Generally yes. Driveways, walkways, patios, and similar hard surfaces count toward the 75 percent impervious cap under ROH 21-3.70-1. Pervious pavers with approved drainage may be credited.
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.
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