Zoning Guide

ADU Rules in Honolulu, Hawaii

Last updated: Verified:

Honolulu is Hawaii's capital and the only incorporated municipality in the City and County of Honolulu, which governs the entire island of Oahu. Hawaii has allowed "ohana dwelling units" (ADUs) since the 1980s. Hawaii Act 245 (2022) required all Hawaii counties to adopt ADU ordinances, and Honolulu enacted Ordinance 22-7 (effective 2023) with updated ADU standards.

Hawaii State ADU Law (Act 245, 2022)

Hawaii Act 245 (SB 3202), effective 2022, requires Hawaii counties to:

  • Allow ADUs in residential zones by right
  • Streamline ADU permitting
  • Expand ADU size allowances

Honolulu ADU Framework

Honolulu's Land Use Ordinance (LUO) governs ohana/ADU standards. Honolulu Ordinance 22-7 (2023) expanded ADU allowances.

Permitted ADU Types

  • Detached Ohana Unit (ADU): Standalone structure on the lot
  • Attached Ohana Unit: Addition to primary dwelling with own entrance
  • Accessory Dwelling Unit (interior): Interior conversion

Size Limits

  • Standard ADU: Up to 800 sq ft (expanded under Ord. 22-7)
  • Varies by zone — contact DPP for current standards
  • Historical ohana limit was smaller; recent ordinance expanded allowances

Setbacks

Per Honolulu LUO for residential zones:

  • Front: Per base zone
  • Side: 5 feet minimum
  • Rear: 5 feet minimum

Height

  • Detached ADU: Per zone height limit (typically 25–30 feet)

Unique Hawaii Considerations

  • Land Use Commission: Hawaii has state-level land use zoning. Most residential areas are in Urban District, which is required for ADUs
  • Soil/Geological: Some Oahu properties have soil or geological concerns (volcanic rock, expansive soils)
  • Coastal/Shoreline: Properties near the shoreline are subject to Hawaii's coastal zone management requirements

Permit Process

  1. Verify zoning: Confirm Urban District designation and Honolulu zone
  2. Pre-application: Contact DPP for pre-application consultation
  3. Submit permit application: City & County of Honolulu DPP
  4. Building permit: Honolulu Building Code applies
  5. Inspections and CO: Required before occupancy

Contact

City & County of Honolulu Department of Planning and Permitting 650 South King Street, 7th Floor, Honolulu, HI 96813 Phone: (808) 768-8000 Website: honolulu.gov/dpp

Disclaimer: Honolulu's ADU ordinance was updated in 2023. Verify current standards with the DPP before starting any project.

More about Honolulu Zoning

Building PermitsSetbacks & Height Limits

Sources

  1. City & County of Honolulu Land Use Ordinance — ROH Chapter 21·codelibrary.amlegal.com·Accessed 2026-05-24·Direct link
  2. Hawaii Act 39 (SB 3202, 2024) — Urban development / ADU mandate·data.capitol.hawaii.gov·Accessed 2026-05-24·Direct link

FAQ

Are ADUs allowed in Honolulu?
Yes, on qualifying lots under the current Land Use Ordinance and DPP requirements. Hawaii Act 39 also requires counties to update local ordinances by December 31, 2026 to allow at least two ADUs on residentially zoned lots, so confirm the effective local rules when filing.
Is an ʻohana dwelling the same as an ADU?
No. Honolulu regulates accessory dwelling units and ʻohana dwellings as separate use categories with different requirements. Use the DPP guidance and LUO section for the use you actually propose.