Do I need a permit for accessory dwelling unit (adu) in Johnston County?
Yes. In North Carolina, accessory dwelling unit (adu) generally requires a permit, and Johnston County is no exception.
NCGS 160D-1110(a) requires a permit before constructing any building, and a new dwelling adds load-bearing structure, plumbing, and wiring, all of which fall outside the $40,000 exemption in subsection (c). A local government may not require the plans for a one- or two-family dwelling to be sealed by an engineer or architect unless the State Building Code requires it (160D-1110(b)). The owner exemption from general contractor licensing in NCGS 87-1(b)(2) applies only to a building intended solely for occupancy by the owner and family, and it is presumed not to apply if they do not occupy it for 12 months after completion. An ADU built to rent that costs $40,000 or more generally needs a licensed general contractor. Anyone who installs plumbing or heating on property intended for sale or mainly for rental is treated as engaged in the business under NCGS 87-21(a)(5), so a rental ADU needs licensed plumbing and heating contractors. The electrical homeowner exemption likewise excludes property intended for rent (NCGS 87-43.1(5a)).
Local detail for Johnston County: County Building Inspections issues building permits for the unincorporated county and by contract for the Town of Smithfield, Town of Selma, Town of Kenly and most smaller Johnston County towns (those towns handle only zoning permits).
Documents you may need
- Building permit application with construction plansRequired
- Site plan with setbacks and utility connectionsRequired
- Electrical, plumbing, and mechanical permitsLikely required
- Energy code compliance documentationLikely required
- Septic or sewer approval for the added dwellingSometimes required
Possible inspections
- Footing and foundation inspections
- Rough-in and framing inspections
- Insulation inspection
- Final inspection
Frequently asked questions
- Do I need a permit for accessory dwelling unit (adu) in Johnston County?
- Yes. In North Carolina, accessory dwelling unit (adu) generally requires a permit, and Johnston County is no exception. The documents and inspections sections on this page list what the building department typically asks for.
- Who issues the permit in Johnston County?
- The local building department for Johnston County handles permitting. This page lists its contact details and online portal. Your mailing city is not always the permitting authority, so confirm the jurisdiction before you apply.
- How do I find out the exact requirements for my project?
- Run the free PermitRoadmap check for your specific project and answers. It returns the likely permits, documents, inspections, and next steps, each linked to its official source.
PermitRoadmap is an independent informational service and is not affiliated with any city, county, state agency, or permitting authority. Results are informational and do not replace confirming requirements with the local permitting authority.