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  • Writer's pictureShaila Campbell

Accessory Dwelling Units

Recently, I've had more clients wanting both a home to live in, but also one that provides for a little additional income. Accessory Dwelling Units are a great way to accomplish this! Now, there aren't a lot of homes with completed ADU's built, so a homeowner may have to take matters into their own hands to apply for and build an ADU. But first, here's a little background:

In 2015, Mayor Kirk Caldwell signed an Ordinance introducing the possibility of Accessory Dwelling Units. An ADU is an accessory or second dwelling unit that includes it's own kitchen, bedroom, and bathroom. It can be either attached or detached from the primary dwelling. The goal was to help the shortage of affordable housing on Oahu, and rental housing in particular.

ADUs are required to be built on Residential zoned property, and the allowable size would be 400-800 sq ft depending on your lot size. One off-street parking is also required somewhere on the lot. (However, there are exceptions if the property is located w/in a one-half mile of a rail transit station, the parking requirement could be waived.)

There is also a requirement for adequate sewer and water capacity to accommodate an ADU. In addition, any CC&RS would also need to allow for ADUs. This can be a major challenge in certain areas that do not allow for secondary dwelling units (for example, Waialae Iki, Mililani Town Association, or Villages of Kapolei are a few examples). The homeowner will be asked to sign an restrictive covenant stating that they will reside in either in the primary dwelling or the accessory dwelling (ultimately deterring a homeowner from moving out and renting both the dwelling and accessory dwelling at one time). It also provides language stating that the homeowner would need to rent to a long germ tenant and prohibits the property from being CPR'ed.

It's important to note that ADU's are different than Ohana Dwellings. The key difference being that Ohana Dwellings restrict occupancy to family members, they require two off-street parking spaces, and have no size limitations. Whereas ADU's allow occupancy by non-family members and generally require only one off-street parking, and there is a size restriction for the ADU itself. However you can apply to convert your Ohana unit or other accessory structure into an ADU with a building permit. Non-conforming structures can also be converted into an ADU, however it will need to conform to current standards.

For more information, here are a few good resources and articles on ADUs:

Department of Planning and Permitting:

Hawaii Appleseed:

Hawaii Business Magazine:


Questions? For more info, call Shaila at 808-741-7155 or email Hawaii Homes & Estates LLC. License No: RB-20456.


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