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 — 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