Garage Conversions: Honolulu vs Urban Honolulu
How do garage conversions rules compare between Honolulu, HI and Urban Honolulu, HI?
Honolulu and Urban Honolulu have similar restriction levels.
Honolulu, HI
Honolulu County
Honolulu's LUO § 21-5.720 allows garage and accessory structure conversions into accessory dwelling units in residential zones, subject to floor area limits, parking requirements, and a building permit from DPP.
View full Honolulu rules →Urban Honolulu, HI
Honolulu County
Urban Honolulu garage conversions must meet ADU rules in ROH Sec. 21-5.720 plus building-permit requirements in Sec. 18-3.2, and lost parking must be replaced on-lot even on tight urban parcels.
View full Urban Honolulu rules →Key Facts Comparison
| Fact | Honolulu | Urban Honolulu |
|---|---|---|
| Minimum lot size | 3,500 sq ft | - |
| Max ADU size (small lot) | 400 sq ft (3,500–4,999 sq ft lot) | - |
| Parking requirement | 1 space per ADU (may be waived) | - |
| Transit waiver radius | Within 0.5 mile of rail station | - |
| Governing section | LUO § 21-5.720 | - |
| ADU Section | - | ROH Sec. 21-5.720 |
| Permit Section | - | ROH Sec. 18-3.2 |
| Parking Rule | - | Replace on-lot |
| Amnesty Cutoff | - | September 14, 2015 |
Highlighted rows indicate differences between cities.
Honolulu FAQ
Can I convert my garage to a rental unit on Oahu?
Yes, if your lot is at least 3,500 sq ft in a residential zone and you owner-occupy the property. You need a building permit from DPP and must meet floor area, parking, and building code requirements under LUO § 21-5.720.
Do I need to add a parking space when converting my garage to an ADU?
Generally yes, one additional off-street parking space is required. It may be waived if your lot is within 0.5 miles of a Honolulu rail station or if topography makes parking infeasible per DPP.
Are there any fee waivers for ADU conversions?
Starting July 1, 2025, qualifying ADU projects are exempt from certain wastewater system facility charges. Regular building permit fees based on project value still apply.
Urban Honolulu FAQ
Can I convert my carport into a studio in Kapahulu?
Only with a building permit under ROH Sec. 18-3.2. If a kitchen is added it counts as an ADU under Sec. 21-5.720, and you must replace lost parking on the lot.
What if the conversion was done without a permit years ago?
Conversions completed before September 14, 2015 may qualify for an after-the-fact permit. Otherwise the owner must legalize the work or restore the original garage.
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