Benefits of Adding an Accessory Dwelling Unit (ADU) to Your Property

What is an ADU?

Accessory dwelling units (ADUs) — also known as mother-in-law units, guest houses, or backyard cottages — are units that typically include their own bedroom, bathroom, kitchen, and living space and are built on the same property as the main home. Detached accessory dwelling units (DADUs) are the same concept, except they are detached from the main home, often built on a different area of the property. For the purposes of this article, we will be discussing both structures under the term of ADU.

Popular in the early 20th century, ADUs saw a decline in construction post-WWII when families began moving toward the newly developing suburbs, only to recently come into favor once again as a beneficial option for homeowners.

New Seattle ADU Legislation

Seattle City Councilmember Mike O’Brien has recently proposed legislation that would ban the construction of overlarge “McMansion” houses on small properties and lighten the rules and regulations imposed on ADUs in King County.

This legislation, currently under review, would encourage homeowners and developers to build additional living spaces on properties rather than tear down houses in older neighborhoods in order to build giant, expensive single-family homes. The potential legislation would hope to add approximately 4,500 new accessory dwelling units, mitigating urban sprawl and providing more varied and economically feasible living options in the city.

Why Build an ADU?

Building an ADU on your property is an excellent decision if you have the space and funds to do so. From personal gains to environmental advantages, here are several benefits to adding an ADU to your property.

Low-Cost Housing for Family Members or Caretakers

An ADU can be a perfect solution to housing for an elderly family member who you want to keep nearby. They can maintain their independence while staying close enough for you to check on them and provide help when they need it. If you live with children or someone who needs additional assistance on your main property, a live-in nanny or caretaker is also a convenient tenant for an ADU.

Space for Hosting Short-Term Guests

If you have a lot of friends and family who like to visit, an ADU is the perfect spot for hosting them during their stay while giving both you and them space and privacy. Setting up an ADU for short-term guests can make their stay more comfortable, especially if the only other alternative is offering up the couch or your own bed.

Passive Income Opportunities

Adding an ADU to your property is the perfect opportunity to start earning some passive income, either on a monthly basis or every now and then for shorter amounts of time.

Since ADUs typically have their own entrance, kitchen, bathroom, and bedroom, you can rent them out as their own living spaces for tenants and earn extra cash to help with your personal living expenses, debt, or savings. Alternately, you can opt to rent your space for shorter-term vacations on websites such as AirBnB, especially if you live in or near a big city or tourist attraction.

Increased Property Value

Building an ADU will almost certainly increase the resale value of your property. The Nest reports that according to a study by the National Association of Realtors, a majority of potential homeowners are willing to pay more for a home with an accessory dwelling unit on the property. This leads many homeowners to consider a cash-out refinance so they can make these improvements regardless of current cash flow.


ADUs are low-impact, sustainable buildings that use less resources than your average single-family home. Their smaller size means they require less energy to heat and cool, keeping utility costs low and reducing carbon emissions.

Neighborhood Aesthetic

Designing an ADU to add space and additional function to your property is much less of an eyesore than constructing a big, blocky “McMansion” in your current space. You can maintain the character and aesthetic of your neighborhood by constructing an ADU that blends with your neighborhood’s architecture and style.

If you’re thinking of adding an accessory dwelling unit to your property, Harjo Construction would be happy to help you every step of the way! Contact us today for a consultation or to find out more about the benefits of ADUs.