Permitting an Accessory Dwelling Unit (ADU)

Based on the 2018 North Carolina Residential Building Code

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ADU FAQs Permitting Information License Requirements Building Requirements Mechanical Requirements Plumbing Requirements Electrical Requirements

The Accessory Dwelling Unit (ADU) text change was adopted by the Raleigh City Council on July 7, 2020. It is effective on July 22, 2020.  As a result of this text change, ADUs are allowed in the following zoning districts: R-1, R-2, R-4, R-6, R-10, RX, OX, NX, DX, and CX.

Read the full text change ordinance.


Question Answer
What is an ADU? Accessory Dwelling Unit (ADU) rules and regulations apply to a self-contained dwelling unit that is located on the same lot as an existing principal detached or attached dwelling for single-unit living. The ADU shall be independent of and subordinate to the principal dwelling.
What is included in an ADU? ADUs include a living room, sleeping area, kitchen, bathroom, and have a lockable external entrance. An ADU may be located above a garage. ADUs may be detached, attached, or internal to the principal dwelling.
What type of "use" is an ADU? Only residential uses are permitted in ADUs, and they must meet the requirements of Section 2.6.3 of the UDO.
What are the size requirements?

ADUs shall be located on the same lot as a principal dwelling and meet one of the following:

  1. The gross floor area of the accessory dwelling shall be less than the gross floor area of the total principal dwelling.
  2. Shall be affixed to or constructed on a permanent foundation and not be a manufactured home or moveable structure.

See the accessory structures section in the TC-16-19 text change for size restrictions.

How many ADUs can I have on my property? Only one ADU is allowed per single lot.
Can my ADU be on wheels? No. It must have a permanent foundation.
Extra information:
  1. If attached or internal, it shall be independent of the principal dwelling unit.
  2. It shall be accessed by an independent, lockable external entrance.
  3. ADUs cannot be sold apart from its principal dwelling unit.
  4. It shall meet all relevant standards and requirements of the UDO, provided however accessory dwelling units shall not be subject to Article 6.7 Accessory Uses and Structures and Sec. 7.1.2.C Parking Requirements by Use.


Permitting Information

The following applications and documents are required to permit an ADU:

See the Development Fee Guide for current permit fees. 

License Requirements

  • A licensed NC General Contractor is required for projects with a total project valuation greater than $30,000.
  •  If Owner/Builder exemption as described in NC General Statute §87-1 is being claimed in lieu of licensed contractors (building or trade), a statement from the owner that the ADU will be built solely as Not For Rent is required prior to issuance. That statement will become part of the permanent record for the project. Please refer to NC General Statute §87-1 for further details on the Owner Exemption qualifications.

Building Requirements

Type Requirements
  • Utility Services such as electric, water, and gas are required to be individual service meters unless the utility services are included as part of the rent as noted in the lease agreement per G.S. 143-151.42. The addition of master electrical and/or natural gas meters may be allowed.
Emergency Egress Section R-310
  • All ADUs are required to have a minimum of one emergency egress directly to the exterior.
  • ADU in attic rooms requires separate emergency egress stairs apart from interior stairs.
  • ADU rooms above the garage are required to have emergency egress directly to the exterior.
  • ADU in basement rooms below grade (Non-daylight basement) are required to have emergency egress stairs and emergency escape such as window wells.
  • All ADU units are required to have an emergency escape.
Fire Ratings Section R-302
  • ADUs in a separate building are required to meet all fire ratings as applied to multiple buildings on the same lot. All windows and penetrations in walls between the separate buildings are to meet placement and protection as required for separation from buildings and lot lines.
  • Rating between the existing dwelling and the ADU whether inside the existing dwelling (basement or attic conversion) or addition attached to the existing dwelling. Treated as duplex 1-hour common separation.
  • ADU in the attic of a garage requires the ceiling in garages over parking need 5/8” Type X, rated sheetrock. Staircase are required to be separated from garage area with ½” sheetrock and provide emergency egress directly to the exterior, with a rated door on the interior if present.
  • ADU in attic rooms requires a one-hour rating ceiling below with all penetrations protected.
  • ADU in basement rooms requires a one-hour rated ceiling with all penetrations protected. Doors to other living units will be rated 20 minutes.


Mechanical Requirements

Type Requirements
General Section M-1602
  • Each dwelling unit must have separate HVAC systems.
  • HVAC Return Air number and location requirements.


Plumbing Requirements

Type Requirements

Water Services Section P-2903

  • Each Dwelling unit is required to provide shut-off valves that are accessible from every tenant space without the use of a ladder or tool.  

Sewer Separation Section P-2601

  • Each building with plumbing fixtures is required to have a separate sewer connection. 


Electrical Requirements

Type Requirements
Branch Circuits
  • Each dwelling unit shall be provided with a separate electrical meter and equipment.
  • Branch circuits in each dwelling unit shall supply only loads within that dwelling unit or loads associated only with that dwelling unit. NEC 210.25(A).
  • Branch circuit installed for lighting a common area of a two-family dwelling cannot be supplied from the equipment that supplies an individual dwelling unit. NEC 210.25(B).
  • Smoke detectors to be hard-wired and interconnected with the existing dwelling when an area inside the existing dwelling or attached to it per R-314.
  • Tenant shall have ready access to all overcurrent devices protecting the conductors supplying that occupancy. There is an exception to the service and/or feeder overcurrent device. NEC 240.24(B) also see 230.72(C), 225.35, and 225.40.




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