Garage Conversions: Honolulu vs Waipahu
How do garage conversions rules compare between Honolulu, HI and Waipahu, HI?
Honolulu and Waipahu 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 →Waipahu, HI
Honolulu County
Converting a garage in Waipahu is treated as ADU creation, requires building permits, and typically requires replacement off-street parking. This is a common option on Waipahu's dense lots.
View full Waipahu rules →Key Facts Comparison
| Fact | Honolulu | Waipahu |
|---|---|---|
| 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 | - |
| - | - |
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.
Waipahu FAQ
My grandparents' Waipahu garage was converted decades ago. Is it legal?
If converted before September 14, 2015, you may qualify for an after-the-fact permit under Sec. 21-5.720. Contact DPP to review your property's records.
Do I really need replacement parking for a garage conversion?
Usually yes. ADU rules typically require replacement off-street parking when an enclosed garage becomes living space. DPP confirms the exact requirement.
Compare other topics
See how Honolulu and Waipahu compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool