ADU Frequently Asked Questions

The following are frequently asked questions (FAQs) about ADUs.


Why are ADUs important?

ADUs can help address the problem of affordable housing by allowing existing homeowners to build a second unit on their property to rent out. In addition, seniors will have the option to “age in place” by moving into an ADU and renting the larger home for additional income.

Where can I build an ADU?

ADUs are allowed on properties in unincorporated Wake County that are zoned to allow single-family or multifamily residences, subject to compliance with the applicable development standards. ADUs are also allowed within some municipal boundaries. Check your local regulations to find out what's allowed.

What are the different types of ADUs?

There are many ways to build ADUs which fall under two main ADU categories:

Detached ADU

A living unit that is physically separated from the main house and its attached garage, not sharing a common wall or other conditioned space, including:

  • A new detached structure to create an independent living unit.
  • Converting an existing detached accessory structure, such as a garage, workshop, office, or art studio room, into a separate living unit.
  • A residential addition to an existing detached structure, such as adding a separate living space above or adjacent to an existing detached garage.

Attached ADU

A separate living unit that is within or connected/attached to an existing or proposed primary house or its attached garage, having a wall and/or other conditioned space in common, including:

  • Converting an existing non-living space (e.g., storage area, attached garage, attic, crawl space) into a living unit.
  • Remodeling an existing permitted living space within the main house to create a separate living unit.
  • Adding square footage (an addition) to the primary home, for example, adding a second story or extending the main floor to create a living unit.

Are owners required to live on the property?

No, homeowners are not required to live on the property. 

Can pre-manufactured, modular or mobile homes be used as an ADU?

Yes, they can be used as ADUs, provided they comply with the provisions related to ADUs and applicable standards, such as but not limited to building code, wastewater, etc.

What if I have a septic system?

If your property is served by a septic system (i.e., an onsite wastewater system), an Accessory Dwelling Unit may alter the wastewater design flow of the septic system, resulting in the need for additional wastewater permits. Further information regarding requirements may be obtained from: 

Health & Human Services-Onsite Water Protection
 - Wastewater/Septic:  
 919-856-7434  or
Groundwater/Well:    919-856-7400

Do I need to obtain a separate address for an ADU?

The process for assigning an address to an ADU is initiated when the building permit application has been submitted for review by staff.