ADU Rules: Honolulu vs Pearl City
How do adu rules rules compare between Honolulu, HI and Pearl City, HI?
Honolulu and Pearl City have similar restriction levels.
Honolulu, HI
Honolulu County
Honolulu allows one accessory dwelling unit on residential lots of 3,500 sq ft or more. Size is capped at 400–800 sq ft depending on lot size. Owner must live on the property and ADUs may only be rented long-term (six-month minimum).
View full Honolulu rules →Pearl City, HI
Honolulu County
Pearl City homeowners, including military families near Pearl Harbor, may build one accessory dwelling unit per zoning lot in eligible residential districts, subject to parking, occupancy, and rental-duration limits.
View full Pearl City rules →Key Facts Comparison
| Fact | Honolulu | Pearl City |
|---|---|---|
| Minimum lot size | 3,500 sq ft | - |
| Max ADU size (small lot) | 400 sq ft (3,500–4,999 sq ft lot) | - |
| Max ADU size (large lot) | 800 sq ft (5,000+ sq ft lot) | - |
| Minimum rental term | 6 months (180 days) | - |
| Owner occupancy required | Yes — main house or ADU | - |
| - | - |
Highlighted rows indicate differences between cities.
Honolulu FAQ
Can I rent my ADU on Airbnb or use it as a vacation rental?
No. ADUs are expressly prohibited from being used as bed and breakfast homes or transient vacation units. All rentals must be for a minimum of six months under a written lease.
Do I need a permit to build an ADU or convert an existing structure?
Yes. A building permit is required. Structures built without a permit before September 14, 2015 may obtain an after-the-fact permit to be converted to an ADU.
What happens if I no longer live on the property?
The ordinance allows limited hardship exceptions (e.g., military deployment or serious illness). All other absences require the director's confirmation; failing to maintain owner-occupancy is a code violation.
Pearl City FAQ
Can a military family add an ADU for visiting relatives?
Yes, if the property is in an eligible residential district and meets ADU standards. Long-term rental is allowed, but short-term rental under 30 days is not.
Does the ADU need its own parking stall?
Yes, ADUs typically require an additional off-street parking space under Sec. 21-5.720. Verify the specific requirement with DPP before applying.
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