Hawaii ADU Laws

Complete 2026 guide to accessory dwelling unit regulations

○Local Control Only

📋Quick Facts

Max Size
1,000 sq ft
Owner Occupancy
May be required
Parking
Set locally
Approval Process
Varies locally

📜Recent Legislation

HB516 (2025) - Repealed previous state requirement for counties to allow at least two ADUs on all residentially zoned lots

⚠️Key Requirements & Restrictions

  • •Previously had statewide requirement for 2 ADUs per lot but HB516 (2025) repealed it
  • •Honolulu Ordinance 25-2 (Jan 2025, effective Sept 2025) allows ADUs
  • •ADUs not allowed on CPR (condominium) lots
  • •Size limits: 500 sqft for lots under 5,000 sqft, 1,000 sqft for larger lots
  • •One parking stall required (waiver possible near transit)

📖Detailed Analysis

Hawaii REVERSED from state mandate to local control - HB516 (2025) repealed previous state requirement for counties to allow at least two ADUs on all residentially zoned lots. Honolulu adopted Ordinance 25-2 (Jan 2025, effective Sept 2025) in response to previous state direction before repeal. Current status: allows one ADU on properties with multiple dwellings (main + ohana) if not CPR'd. Size limits: 500 sqft (under 5,000 sqft lots), 1,000 sqft (5,000+ sqft lots). One parking stall required unless waived near transit. Hawaii represents rare case of state retreating from ADU mandate back to local control.

🔗Official Resources

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⚠️ Disclaimer

The information provided on this website is for general informational purposes only and does not constitute legal, financial, or professional advice. ADU laws, regulations, and requirements vary by jurisdiction and change frequently. While we strive to keep this information accurate and up-to-date, we make no representations or warranties of any kind about the completeness, accuracy, reliability, or suitability of this information. Always consult with qualified local professionals, including attorneys, architects, and your local planning department, before making any decisions regarding ADU construction or investment. Use of this information is at your own risk.

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Last updated: February 2026