What is an ADU?

Accessory Dwelling Unit a.k.a. Granny Flats or Backyard Cottages

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Benefits of ADUs ADUs in Raleigh What do ADUs look like? FAQs
Illustration of an ADU and its relation to a primary residence.

An Accessory Dwelling Unit (ADU) is a small, self-contained home that is located on the same lot as a primary dwelling. You can read the Unified Development Ordinance standards for ADUs. ADUs may be detached, attached, or internal to the primary dwelling. An ADU may also be located above a garage or in a basement. They can be one story or two stories.  

ADUs fill a small but important niche in an equitable housing supply and offer a range of benefits for Raleigh residents:

  • Housing costs have increased steadily in Raleigh, particularly in high-demand neighborhoods close to downtown. ADUs can increase the supply of relatively more affordable housing wherever they are built. The small size and absence of land costs often lead to the units renting at lower rates than apartments in the same neighborhood. The small size and integration within established neighborhoods make ADUs a desirable housing type for renters who don’t want to live in larger multifamily settings.
  • ADUs are a housing type for those wishing or needing to “age in place”. ADUs offer aging homeowners the opportunity to move into a smaller, more accessible home in their backyard while retaining their larger, main house for family or renters.
  • ADUs are also ideal homes for people with disabilities or medical challenges for whom closer family attention and care are necessary.
  • ADUs can also be an effective tool in preventing displacement. Increasing ADU supply in high-demand, higher-income neighborhoods close to downtown could reduce upward pressure on rents elsewhere, particularly in traditionally Black neighborhoods close to downtown where displacement risks are high. The City is also exploring dedicated anti-displacement programs for future implementation.
  • ADUs can also be a source of needed additional income for many types of households. Over time, most ADUs will deliver a significant return on investment. 

Benefits of ADUs

Amid a nationwide housing crisis, we need many models of housing to meet many needs. ADUs increase housing stock at a scale more compatible with traditional neighborhoods. These are not large-scale developments and can be designed to fit in visually with existing neighborhoods. ADUs can help keep families in their neighborhoods by accommodating adult children living at home and aging parents. 

ADUs can also increase homeowners' equity. Renting a second unit adds an income stream and increases property value. 

ADUs in Raleigh

The City Council adopted a new ordinance (TC-16-19) in July of 2020 to allow ADUs in Raleigh. The ordinance was the result of continuous engagement and study on ADUs. Read the full text of the ordinance.

The City of Raleigh offers a list of programs and resources to encourage, support, and incentivize this type of construction:

  • Fast-Track ADU (or ADU Fast-Track) Program - A program aimed at making ADU construction more accessible to Raleigh residents. The city will select plans submitted by designers to be reviewed for building code compliance, reducing the time it takes for a typical ADU to be reviewed. Individual property owners can purchase these fast-track ADU plans for a fee far below the typical cost to design one.
  • ADU Monitoring Program - A program to monitor ADU development in Raleigh to better understand the impacts of ADUs and their role in providing needed density and greater affordability.
  • Permitting and Facility Fee Reduction Program - To reduce the cost to build an ADU, the city has eliminated building permits and some facility fees for ADUs.
  • UDO Reform - The City is in the process of reducing setbacks, allowing smaller and flag lots, and permitting ADUs on one property. Recently, the City Council voted to allow a broader range of construction types for ADUs, providing greater flexibility to prospective builders.
  • Affordable ADU Bonuses Program - The City is studying the feasibility of a program that would grant a bonus amount of square footage or permitted unit density in exchange for affordability guarantees.
  • Anti-Displacement Loan Program - ADUs can be an effective tool in fighting the displacement of renters and homeowners struggling with housing costs. The City is studying the feasibility of a loan program to help homeowners at risk of displacement build and rent an ADU as a source of added income. 

What do ADUs look like?

Illustration of an design types for ADUs.


  • 450 – 800 square feet
  • 1000 sq. ft. are allowed on specific sites 


  • New construction
  • Studio
  • One bedroom
  • Two bedroom
  • Garage conversion 


  • Varies


Can I build an ADU in a Historic Overlay District (HOD)?

Do I need to provide additional parking for the ADU?

  • No. Additional parking does not have to be provided.

I am part of a Homeowners Association (HOA), can I build an ADU?

  • Maybe – contact your HOA and ask if ADUs are permissible in your neighborhood and if there are any additional design requirements.

Are there additional resources available to help with the construction of ADUs?

  • The City has put out an ADU Open Call for fast-tracking designs that will be checked for building code compliance and available to you to license and build. This saves time in searching for a designer and going through a typical design and permitting process. 



Dhanya Sandeep
Planning Supervisor
Planning and Development

Planning and Development