These spaces are sometimes referred to as granny flats or in-law apartments. As stated in the City and County of Honolulu Land Use Ordinance, ADUs are only allowed on single-family lots. Accessory dwelling units are not to be confused with Honolulu’s ohana units, separate living spaces with a kitchen, bathroom, and sleeping area exclusively for family members of the homeowner.
City & County of Honolulu Basic ADU Requirements
1. Your lot must be zoned in a residential or country district
Check your zoning using the DPP’s Property Search. Under Zoning (LUO) the chart must list one of the following: R-3.5, R-5, R-7.5, R-10, R-20, or Country District.
2. Your lot area must be at least 3,500 square feet
The DPP’s Property Search also lists the area of the lot in square feet.
3. Your lot cannot be landlocked
There must be a direct access road to the property.
ADUs are allowed on a case-by-case basis. Please check with the DPP.
4. Your lot must contain one single-family dwelling
ADUs are not permitted on lots where a multi-family unit exists, such as a duplex or apartment complex. Additionally, only one ADU or ohana unit is permitted per lot. If you already have an ohana unit built, you cannot add an ADU. Alternatively, you may be able to convert the ohana into an ADU.
5. The property owner, family of the property owner, or designated representative must reside on the property
The homeowner (or family of the homeowner) must live on the property so long as one of the units is occupied. For example, if the ADU is being rented, the homeowner must live in the main house. If the main house is rented out, the homeowner must live in the ADU. There are exceptions for “unforeseen circumstances” such as an active military deployment or illness that prevents the property owner from living on the property.
6. The property owner will record covenants running with the land with the Bureau of Conveyances or the Land Court of the State of Hawaii, or both
This agreement ensures the property owner does not sell the ADU separate from the rest of the property; the lot cannot be divided into two separate properties. The Declaration of Restrictive Covenants also lists the rules about owning and renting an ADU. More details on the Bureau of Conveyances and the restrictive covenants are available here.
7. If you are in a private covenant prohibiting ADUs, you cannot build one
Check with your homeowners’ association if there are any rules prohibiting second dwellings or rental properties. An ADU permit does not supersede any private agreements.
8. You must provide a parking space for the ADU in addition to the required parking for your existing house
There is an exemption for lots that are located within one-half mile of a rail station.
9. You must abide by the ADU floor space limitations
|Lot Size (square feet)||Max. Floor Area (square feet)|
|3,500 to 4,999||400|
|5,000 or larger||800|