ADU Benefits: Adding an Accessory Dwelling Unit to Your Property

Seattle is one of the most desirable cities in America, and as such, the demand for residential properties is increasing. Adding an accessory dwelling unit (ADU) can be a great choice for expanding your family’s living space or a viable short-term option for others moving into the area—one that provides you with additional income.  

What is an ADU? ADUs—sometimes called a backyard cottage, mother-in-law suite, secondary dwelling unit or carriage house—come in many different forms, from renovating your basement to a full-fledged apartment above the garage. Whatever form they take, ADUs offer several benefits that are worth considering if you’re looking for extra space. 

City of Seattle ADU Rules 

In August 2019, the City of Seattle adopted new rules to remove regulatory barriers that prevented or discouraged property owners from adding an accessory dwelling unit. 

These new ADU rules encourage homeowners and developers to build additional living spaces on properties rather than tear down houses in older neighborhoods to build giant, expensive single-family homes. According to the City of Seattle, “The Seattle Department of Construction and Inspections (SDCI) issued permits for 237 attached accessory dwelling units (AADUs) and 276 detached accessory dwelling units (DADUs) in 2020, an increase of 53 percent and 112 percent, respectively, over units permitted in 2019.” 

Source: City of Seattle Accessory Dwelling Units Annual Report, September 2021 

Benefits of Adding an Accessory Dwelling Unit (ADU)

Building an accessory dwelling unit on your existing property is an excellent decision if you have the space and funds to do so. From a rental income generator to environmental advantages, there are several benefits to adding an ADU to your property. Here are just a few of them: 

Affordable Housing for Family Members and Caretakers 

An ADU can be a perfect solution for housing a family member, such as a college-aged kid or an older relative you want to keep nearby. Your loved ones 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, your ADU can be the ideal solution for a live-in nanny or caretaker. 

Queen Anne Basement ADU Remodel

Space for Hosting Short-Term Guests 

If you have friends and family who like to visit, an ADU can provide both space and privacy during their stay. Seattle is a tech town that attracts employees from across the globe, and they often host family members visiting from another country for extended periods of time. Constructing 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. 

Rental Income  

Adding an accessory dwelling unit to your Seattle property is the perfect opportunity to start earning some passive income, either monthly 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 on websites such as Airbnb, especially in Seattle and King County where tourism attracts near 20 million visitors annually. 

Detached Accessory Dwelling Unit (DADU) project in Greenwood.

Increased Property Value 

Adding an accessory dwelling unit to your property will almost certainly increase the resale value of your home. According to a 2021 Porch Study, “… in America’s biggest cities, a home with an ADU is priced 35% higher on average than a home without one. [Additionally,] ADU sales are growing fastest in Portland (+23%), Dallas (+19%), and Seattle (+18%).” The ADU trend is leading 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 fewer resources than your average single-family home. Their smaller size means they require less energy to heat and cool, which keeps utility costs low and reduces carbon emissions. 

Neighborhood Aesthetic 

Designing an ADU to add space and additional function to your property is much less of an eyesore than reconstructing your main house into a big, blocky “McMansion.” You can maintain the character and aesthetic of your street 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 is happy to help you every step of the way! 

Explore our previously completed ADU projects or contact us  to schedule a consultation.