Honolulu ADU permit requirements
Last reviewed: June 22, 2026
Quick answer
Permitting an accessory dwelling unit (ADU) in Honolulu, Hawaii means pulling a building permit from the local authority that issues it. ArchPermit tracks 12 source-cited requirements (8 required, the rest conditional) for this jurisdiction. Submittals go through HNL Build → ePlans (ProjectDox). These requirements were last reviewed June 22, 2026; confirm the exact forms and fees with the local permitting authority.
A source-cited checklist of what an ADU (accessory dwelling unit) permit package needs in City and County of Honolulu. Every item links to its authoritative source; items that vary are flagged to confirm locally.
Hawaii has no incorporated cities, so the City & County of Honolulu (DPP) issues ADU permits for all of Oʻahu. The ADU program (Ordinance 15-41 / Bill 20, 2015) is distinct from the older 'ohana' dwelling. Only one ADU per zoning lot (the lot cannot already have more than one dwelling unit / two-family / ohana / guest house); minimum 3,500 sf lot in R-3.5/R-5/R-7.5/R-10/R-20 or Country District. The ADU cannot be sold separately: owners must record a covenant (no condominium-property-regime split; long-term residential, 6-month minimum) before a permit issues. DPP recommends the ADU Public Facilities Pre-Check first (infrastructure adequacy). Per the current LUO (Ord 25-2, eff Sep 30 2025) the max size is 500 sf (lots ≤4,999 sf) / 1,000 sf (lots ≥5,000 sf). The 2016 DPP guides showing 400/800 sf are stale.
- ADU Public Facilities Pre-Check Formrequired
DPP's infrastructure/zoning pre-check (sewer/water/fire/roadway adequacy); submitted with the ADU building-permit application. Voids 210 business days after first agency approval.
source · reviewed 2026-06-22 - ADU Restrictive Covenant (recorded)requiredverify locally
A recorded covenant (no separate sale / no CPR split; long-term residential, 6-month minimum), submitted before recording; the permit will not issue until completed. Confirm the current approved covenant form.
source · reviewed 2026-06-22 - Complete Plot Plan Sheetrequired
Entire parcel, all lot dimensions, driveway aprons, off-site utilities, scope of work, all existing permitted structures with addresses, building & required-yard setbacks, easements, and streets.
source · reviewed 2026-06-22 - Construction Drawings (plan set)required
Full plan set uploaded to ePlans; must comply with every item on the Building Permit Plan Format Checklist.
source · reviewed 2026-06-22 - Floor Planrequired
Floor plan for the ADU (also submitted with the Pre-Check).
source · reviewed 2026-06-22 - Internet Building Permit (IBP) Applicationrequired
The building-permit application itself, completed online (started in HNL Build).
source · reviewed 2026-06-22 - Residential Storm Water Management Plan (Appendix G1)required
Required for single-/two-family dwellings in residential zones; template plus Attachment A mapping existing/proposed impervious area.
source · reviewed 2026-06-22 - Title Sheetrequired
First uploaded sheet, with index, data table, owner/project name, legal address, TMK(s), and project description.
source · reviewed 2026-06-22 - Contractor's Statement (DPP-26)conditional
Required when the work is done by a licensed contractor (vs owner-builder).
source · reviewed 2026-06-22 - Electrical Plan + Load Calculationconditional
Separate electrical sheet/diagram; an electrical load calculation is required for new services or added load.
source · reviewed 2026-06-22 - Flood Zone Review Documentationconditional
Required for parcels located in a flood zone.
source · reviewed 2026-06-22 - Zoning Adjustment (ADU) Applicationconditional
Required only when converting an existing legal structure that exceeds the max floor area and/or cannot meet the parking requirement.
source · reviewed 2026-06-22
Honolulu ADU permit questions
- Do I need a permit to build an ADU in Honolulu?
- Yes. An accessory dwelling unit (ADU) in Honolulu requires a building permit. ArchPermit tracks 12 cited requirements for this jurisdiction (8 required, the rest conditional). Always confirm the exact forms, fees, and code edition with the local permitting authority that issues the permit.
- What does an ADU permit package require in Honolulu?
- Core required items include: ADU Public Facilities Pre-Check Form; ADU Restrictive Covenant (recorded); Complete Plot Plan Sheet; Construction Drawings (plan set); Floor Plan; Internet Building Permit (IBP) Application, plus 2 more. Each requirement links to its authoritative source, and nothing is permit-ready until an independent licensed professional reviews and seals it.
- How are ADU permits submitted in Honolulu?
- Honolulu accepts permit submittals via HNL Build → ePlans (ProjectDox). ArchPermit prepares a draft package you can submit there after a licensed architect reviews and seals it.