Accessory Dwelling Units (ADUs), also known as in-law suites or “granny flats,” are “a smaller, independent residential dwelling unit located on the same lot as a single-family home.” 1 Like a normal residential dwelling, ADUs include “full amenities: a kitchen and a bathroom, along with separate entry from the primary dwelling.2
There are three main types of ADUs; “interior, detached, and attached.” An interior ADU is “located within the primary dwelling place. Usually, they are built through conversion of existing space.” A detached ADU is “physically separated from the primary dwelling. They make take the form of a building constructed or converted on the property, or they may be living space added to an existing building.” Lastly, an attached ADU is “added to the primary dwelling without being inside the existing building, such as a room added over an attached garage.”1
| Type | Description |
| Interior | Located within the primary dwelling place. Usually built by converting an existing space. |
| Detached | Physically separated from the primary dwelling place. May take form of a newly constructed, or converted, building on a property. May also be an addition to an existing building. |
| Attached | Added to the primary dwelling place. May be an attic, or room over an attached garage. |
Based on information provided by The National Association of REALTORS® REALTOR® Party Hot Topic Alert, Accessory Dwelling Units.
There are numerous benefits to ADUs, which include adaptability and sustainability. ADUs primarily contribute to sustainability goals by encouraging density.2 “Rather than clearing another lot in a sprawling suburb for a new single-family home, the ADU stealthily adds density to existing neighborhoods, which allows them to tap into the existing infrastructure grid. They can also lead to fewer emissions by encouraging shorter commutes.”2 In terms of adaptability, the use of an “ADU can be adapted for different household types, income levels, employment situations and stages of life.”3
ADUs also have the potential to increase the property value of a home. A 2021 study conducted by Porch Research found that “in the largest cities, a home with an ADU is priced 35% higher, on average, than a home without one.” In Cleveland, for example, the average price of a home without an ADU in 2021 was $95,200; whereas the average price of a home with an ADU was $289,900, that is a whopping 205% difference.4
Do ADUs add value?
Infogram / Porch Research
Infogram / Porch Research
The ADU debate stems from property owners wishing to utilize their property as they see fit, and neighbors worrying that allowing ADUs will cause crowding, traffic issues, and transient residents that lower the property values of surrounding homes.1 However, these potentially negative impacts are “most likely, overstated.” This is because “ADUs are often strictly limited in size, so even an attached or unattached ADU will not be architecturally overwhelming.”1
As Ohio continues to battle the affordable housing crisis, solutions will require creative approaches to new and existing policies, and reimagining what neighborhood and development should look like moving forward. ADUs are an effective, and attractive, approach to this problem by allowing sustainable and cost-effective development in preexisting neighborhoods.
(1) National Association of Realtors. Accessory Dwelling Units. Available at: https://realtorparty.realtor/wp-content/uploads/2020/01/Accessory-Dwelling-with-Links.pdf.
(2) Kruth, J., Paranandi, M. and Conversation, T. (2023) The housing market is so broken that many 40- and 30-something millennials have no choice but to build homes in their parents’ backyards , Fortune. Available at: https://fortune.com/2023/06/06/housing-market-broken-zoning-affordability-millennials-building-tiny-homes-backyard/.
(3) AARP. ADUs Are Good for People and Places (2019) AARP Livable Communities. Available at: https://www.aarp.org/livable-communities/housing/info-2019/adus-are-good-for-people-and-places.html.
(4) Porch Research. 2021 study: How much value do Granny Flats and other accessory dwelling units add to a home? (2021) Porch. Available at: https://porch.com/advice/state-of-adu-market-2021.
