Tag Archives: What is an ADU

The 9 Basic Requirements for Building an ADU in Hawaii

This entry is part 12 of 13 in the series Accessory Dwelling Unit


Since the dawn of property ownership, people have been building smaller dwellings near their pre-existing homes. In Australia, they call them Granny Flats, in certain parts of the continental US, they’re called Mother-in-Law houses and here in Hawaii, the official term is ADU, short for Accessory Dwelling Unit. Like the acronym says, these are little homes that act as complete residential unit accessories to a main house on a shared property. Theoretically, anyone can build an ADU simply by making a nice addition or building with a kitchen, bedroom, and bathroom but officially there are certain legal guidelines for an approved ADU construction. Before you break out your [amazon_textlink asin=’B0033BLWPA’ text=’carpentry tools’ template=’ProductLink’ store=’ownbuilddesig-20′ marketplace=’US’ link_id=’f1717607-e67b-11e7-90ea-89d236139fc9′] or call a contractor, make sure your home and plans conform to the 9 basic requirements for building an ADU.

1) Proper Zoning

Zoning in Hawaii and knowing your exact zone can be a little tricky and ADUs can only be built in six specific zones. Before even thinking about building one of these tiny separate houses, make sure to check your lot’s zone by address and ensure that it matches one of the following:

  • R-3.5
  • R-5
  • R-7.5
  • R10
  • R20
  • Country District

2) Lot is At Least 3,5000 Square Feet

To ensure that there is plenty of room for your ADU, anyone who wants to build one needs to have a house lot that reaches at least 3,500 square feet of space. Fortunately, your original house is allowed to sit on some of it. Rather than breaking out the incredibly long measuring tape, you can check your lot’s size online to figure out if you qualify. Bigger is always better, and you’ll find out why with point nine.

3) Lot is Not Landlocked

To build an ADU, your lot will need to actually make contact with the road. Due to certain access requirements, a landlocked lot cannot hold an ADU. However, you can have an ADU if your lot is connected via driveway to the road by way of an easement through another closer lot. Flat lots are also perfectly fine.

4) Lot Has One Current Dwelling

You cannot build an ADU unless there is only one complete dwelling on your lot. This means that duplexes, apartment buildings, and lots that already have two or more homes on them cannot build an ADU. However, renovated apartments above the garage or in the basement are just fine as long as they’re not legally a second dwelling.

5) Owner or Family Lives On the Lot

To qualify for ADU construction, the homeowner or at least one member of their family needs to live on the lot when the ADU is complete. This means they can either live in the main house or the ADU based on preference, as long as the owner or a family member is in residence. You are allowed to rent out whichever building you’re not going to live in.

6) Record Your Covenants

When you do build an ADU, you are required to record covenants with the land with either the Bureau of Conveyances or the Land Court of the State of Hawaii or both. This ensures that you will never sell the ADU separately from the rest of the property and the lot cannot be subdivided into two separate properties. There are also other related rules in the Declaration of Restrictive Covenants.

7) No ADU Covenant Restrictions

Check any private covenant signed for your land to ensure that it doesn’t prohibit an ADU. If you have already agreed not to build one, starting [amazon_textlink asin=’1600852467′ text=’construction’ template=’ProductLink’ store=’ownbuilddesig-20′ marketplace=’US’ link_id=’cc021150-e67c-11e7-8001-37dd20bbf9c8′] now would be both illegal and quite silly. However, you may not be aware that the prohibition exists to make sure to check with your HOA to be sure.

8) Room For One More Parking Space

An ADU is officially an entirely separate second dwelling and because of this, it’s expected that the resident is likely to have their own car. Therefore to build a legal ADU, you’ll need room within the lot’s parking areas for one more parking space than your lot’s minimum spaces unless the edge of your property is within a half mile of a rail station.

9) ADU Plans Meet Maximum Size

The maximum square foot size of your ADU is limited by the square footage of the lot itself. For a lot at the minimum size of 3,500, your ADU can only be 400 square feet. For just under 5K, it can be up to 800 sq-ft, and for lots above 5K, you can have a much larger ADU.

By the end of this list, you should have a fairly good idea of whether or not you’re legally allowed to build an ADU on your property in addition to your single-family home. If you do decide that an ADU is right for you, your lot, and your family contact us today! We’ll be happy to help you figure out the next steps.


The Benefits of Building an ADU on Your Property

This entry is part 8 of 13 in the series Accessory Dwelling Unit

Owning a home in Hawaii is a wonderful experience. It allows you to build memories and make alterations however you choose to on your land. Many people will buy a single family home and make a number of small to extensive renovations like [amazon_textlink asin=’1561584827′ text=’remodeling the kitchen’ template=’ProductLink’ store=’ownbuilddesig-20′ marketplace=’US’ link_id=’a5e3e5ee-9efd-11e7-bb23-c5ef1967877b’], taking out interior walls between public living spaces, and adding new rooms to the existing structure. Of course, not every renovation has to make use of the current home at all. You could construct outbuildings, design the perfect play ground, or landscape the garden into something fantastic. One of the most useful and potentially lucrative changes you can make to your property is the addition of an ADU or Accessory Dwelling Unit.

What is an ADU?

Knowing what the acronym stands for (Accessory Dwelling Unit) doesn’t actually explain what an ADU really is. These are extra buildings or extensions to a single-family home that can support an entirely separate resident and are particularly popular in crowded Hawaii neighborhoods. They are commonly referred to as ‘granny flats’ or ‘in-law apartments’, but you certainly aren’t required to keep your aging parents and parents-in-law in one if you build it. In fact, many ADU owners and builders are putting them on the renter’s market, becoming landlords without having to buy new investment property.

Unlike normal home extensions, each ADU includes its own kitchen and at least one private bathroom. They are often built as outbuildings in a separate section of a large home lot but can also be built as a comprehensive addition to the current structure. They can even be a conversion of an older section of the house or accessory structure in the yard.

Providing a Source of Income

There are many potential uses for an ADU. If you didn’t build it for a specific relative in mind, you can put the property to use making money to pay for its construction costs, provide [amazon_textlink asin=’0812929896′ text=’extra income for your family’ template=’ProductLink’ store=’ownbuilddesig-20′ marketplace=’US’ link_id=’cfe1b6e7-9efd-11e7-bcbf-81db1592f226′], retirement, or perhaps to pay off your mortgage on the overall property. Most people who build an ADU do so with the intent to rent, which can make a big difference during the current housing crunch.

Alleviating Overcrowding

Because there are so many more people living in Hawaii than there are available single-family homes, it’s quite common for extended families to live together. Building ADUs can give everyone a little extra breathing space by providing separate accommodations. Simply by adding an extra kitchen and bathroom to the property, you can reduce the amount of waiting and jostling in a busy home. ADUs also create flexibility, as the added privacy allows you to rent out space to a non-relative if it’s not currently needed.

Encouraging Aging in Place

Most people, as they age, need less space to take care of and often end up downsizing in order to save the money and energy it takes to maintain a full-sized house. However, an ADU can help seniors who love their homes ‘age in place’ by moving into the smaller residential space and renting out the main house to an eager new family.

Opportunity to Help the Families in Need

There is a serious problem in Hawaii with perfectly capable and hardworking families facing homelessness because there simply aren’t enough affordable houses available. Building and renting out an ADU creates an opportunity for private homeowners to contribute to a solution. Families with nowhere to stay will be more than happy to have a freshly built private apartment and access to single-family neighborhoods. By renting your ADU out at an affordable rate, you can help keep a family out of homelessness while making a good long-term investment.

There are half a dozen reasons to build and ways to use an ADU, it’s simply a matter of preparing for the construction costs and choosing a design. Build it the way you like it, with an efficient floor plan and an exterior that compliments your landscaping. Once it’s done, you can share it with relatives or rent it to a grateful family looking for a new home. For more information about building a new ADU on your Hawaii property, please contact us today!


What’s the 411 with Hawaii ADU’s: The FAQs Continued

This entry is part 7 of 13 in the series Accessory Dwelling Unit

If you live or even occasionally visit [amazon_textlink asin=’1628873140′ text=’Hawaii’ template=’ProductLink’ store=’ownbuilddesig-20′ marketplace=’US’ link_id=’b9643ab7-a226-11e7-ae93-0f338484ecd1′], you’re probably already aware of the intense housing crunch going on, especially when it comes to affordable rental properties for working families. While [amazon_textlink asin=’B015PA9VI6′ text=’homelessness’ template=’ProductLink’ store=’ownbuilddesig-20′ marketplace=’US’ link_id=’fb46d656-a226-11e7-9b2b-b347f01db0bd’] is usually something that happens to people who can’t or won’t work, it’s an unfortunate fact that many families are finding themselves without proper lodgings because there simply aren’t enough homes to go around. For this reason, Honolulu has recently authorized home-owner residents to build small secondary residential homes on their property in order to rent to families in need. These residences are known as Hawaii ADU’s or Accessory Dwelling Units and are a great way for home owners to both alleviate the housing crunch and make a little extra money for their own mortgages.

In a previous post, we covered a few of the FAQs about ADUs from defining our terms to how they compare to ohana units. Today, we’re picking up where we left off to answer more important questions about how you can contribute to the local effort against homelessness.

Frequently Asked Questions Pt 2:

Q: Are owners required to live on the property?

The short answer here is yes, but in truth, it’s a little more complicated. You cannot rent both the main house and the ADU at the same time, but the named owner doesn’t necessarily have to live on the property. In order to rent your ADU, the main house needs to be occupied by a relative by blood, marriage, or adoption to the property owner. However, a designated authorized representative is also allowed.

Alternately, you or a relative can choose to live in the ADU and rent out the main house, which also counts as using your ADU to alleviate the housing shortage. This is a great option for retirees who want to downsize for ease of lifestyle without leaving their family home behind.

Q: Is there a minimum occupancy period for each ADU tenant?

In order to ensure that Hawaii ADU’s are actually being used to help with the housing problem, tenants need to stay at least six months (180 days to be specific) with each lease. This prevents both landlords and tenants from misusing it’s intended purpose, but that also means that it’s inadvisable to Airbnb your ADU between tenants.

Q: Is there enough local sewer and water capacity?

It’s true, not every neighborhood has the infrastructure available to support doubling up on sewer and water needs. For this reason, you’ll need to get approval from all the usual sources including the Department of Planning and Permitting, Wastewater Branch, Traffic Review Branch, State Department of Health, Board of Water Supply, and the Honolulu Fire Department. If they all agree that a new residential structure is OK, you can proceed with building plans.

Q: How much parking is required for an ADU?

Hawaii ADU’s only require one off-street parking spot. This sets them aside from ohana units which require two and therefore permits home owners with smaller yards to contribute to the housing effort.

Q: How big can Hawaii ADU’s be?

It may be tempting to build yourself a near-duplex residential buddy, especially if you have the yard space to spare, but ADUs are, in fact, limited in size based on the size of your lot.

  • Lots 3500 – 4999 square feet can have an ADU of up to 400 square feet
  • Lots 5000 square feet and up are limited to an ADU of 800 square feet.

Q: How many ADUs can I build?

The answer here is only one, but it’s slightly more complex in practice. ADUs fill a secondary residential slot, but can only do so if you don’t already have a secondary residence on your lot. Therefore ohana dwellings, guest houses, and multifamily dwellings like duplexes disqualify a lot from having even a single ADU.

If you’re considering building an ADU on your lot, you’ll need an expert designer who can get your plans through approval the first time around. I have decades of experience and specialize in permit-ready drawings and would be delighted to ensure your ADU project hits the ground running. Please contact me today for more information or plans to build!