Accessory Structures in Honolulu, HI (2026)
8 verified accessory structures rules for Honolulu, Hawaii, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Honolulu allows one accessory dwelling unit on residential lots of 3,500 sq ft or more. Size is capped at 400–800 sq ft depending on lot size. Owner must live on the property and ADUs may only be rented long-term (six-month minimum).
Honolulu ADU Rules: One Unit Allowed on Qualifying Residential Lots
Some RestrictionsADU Permits
Honolulu City and County recognizes two distinct accessory residential units under the Land Use Ordinance (LUO) Chapter 21: the traditional Ohana Dwelling Unit (LUO Sec. 21-5.700) and the Accessory Dwelling Unit (ADU) created by Bill 7 (2015) under LUO Sec. 21-5.730. Both require a building permit through the Department of Planning and Permitting (DPP). Lot size, infrastructure, and zoning eligibility differ between the two.
Honolulu ADU and Ohana Unit Permits
Some RestrictionsADU Impact Fees
Honolulu does not impose a dedicated ADU impact fee, but Board of Water Supply (BWS) Water System Facilities Charges and Department of Facility Maintenance sewer assessment fees commonly add several thousand dollars per ADU. Standard DPP building permit fees scale to construction valuation. Bill 7 ADU applicants also pay a per-unit infrastructure assessment.
Honolulu ADU and Ohana Unit Fees
Some RestrictionsADU Owner Occupancy
Bill 7 ADUs in Honolulu (LUO Sec. 21-5.730) require a recorded covenant restricting use to long-term residential rental (180+ day leases) but do not require owner occupancy of the principal dwelling. Traditional Ohana units (LUO Sec. 21-5.700) historically were intended for extended family but the LUO does not impose a formal owner-occupancy mandate on Ohana units either.
Honolulu ADU and Ohana Owner Occupancy
Some RestrictionsADU Rental Restrictions
Honolulu prohibits short-term rentals (under 90 days outside resort districts, under 30 days in resort districts) of Bill 7 ADUs under both the recorded long-term rental covenant in LUO Sec. 21-5.730 and Bill 89 (2019) / Bill 41 (2022) STR enforcement. ADUs must be rented for 180 days or longer per the recorded covenant. Hawaii state General Excise Tax (GET) and Transient Accommodations Tax (TAT) apply to rentals.
Honolulu ADU Rental Restrictions
Heavy RestrictionsShed Rules
Honolulu allows one-story detached storage sheds of up to 120 square feet on residential lots without a building permit under ROH Ch. 18. Larger structures require a building permit and must conform to zoning setbacks under ROH Ch. 21.
Sheds Under 120 Sq Ft Exempt from Building Permits
Few RestrictionsGarage Conversions
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.
Honolulu Garage-to-ADU Conversion Rules and Permits
Some RestrictionsCarport Rules
Honolulu carports must meet the same Land Use Ordinance (LUO) yard setbacks as the main house unless the homeowner obtains a Zoning Adjustment under ROH §21-2.140-1. A one- or two-car carport may encroach into required front and side yards only if no other viable alternative exists relative to a dwelling legally built before October 22, 1986, or to lot topography, and the carport's horizontal footprint generally cannot exceed 20 feet by 20 feet. A DPP building permit under ROH Chapter 16 is required, and carports do not count as floor area for FAR purposes.
Carport Rules in Honolulu
Some RestrictionsCity and County of Honolulu, Department of Planning and Permitting, Zoning Adjustment: Carports and Garages (rev. Jan. 29, 2025) (citing Land Use Ordinance Sec. 21-2.140-1(a))
A one- or two-car carport or garage in a residential district may encroach into required front and side yards, including those in Special Districts, only under the following conditions: 1. No other viable alternative site exists relative to the location of an existing dwelling (including additions), legally constructed prior to October 22, 1986, and/or to the topography of the zoning lot; and 2...
Looking for Honolulu County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Honolulu city rules.
Accessory Structures in Honolulu County →