ADU Rules in Jacksonville, North Carolina

Jacksonville is the seat of Onslow County in coastal eastern North Carolina. The city is defined by its relationship with the US Marine Corps: Marine Corps Base Camp Lejeune to the east and Marine Corps Air Station New River to the west together comprise one of the most significant military complexes in the world, with a combined active-duty and dependent population that shapes nearly every aspect of Jacksonville's economy, demographics, and housing market. For homeowners considering an ADU, understanding the military overlay environment is as important as the underlying zoning rules.

No Statewide ADU Law — Jacksonville's UDO Governs

North Carolina has no statewide ADU preemption law. ADU regulations in Jacksonville are contained in the City of Jacksonville Unified Development Ordinance (UDO). Properties in unincorporated Onslow County fall under the Onslow County Zoning Ordinance. Confirm your parcel's jurisdiction before proceeding.

Critical: AICUZ Overlay — MCAS New River

Marine Corps Air Station New River operates significant fixed-wing and rotary aircraft operations, creating noise impacts and accident risk that affect residential areas across Jacksonville. The AICUZ (Air Installation Compatible Use Zone) program governs compatible land uses around the installation:

• Noise contour zones: Areas within the 65 dB DNL contour may face restrictions on new residential uses; properties in 70 dB+ zones face more severe restrictions
• Accident Potential Zone I (APZ-I): Immediately below approach and departure paths; residential construction is generally prohibited or severely restricted
• Accident Potential Zone II (APZ-II): Adjacent to APZ-I; residential density increases (such as adding an ADU) may be restricted
• Clear Zones: No construction permitted whatsoever adjacent to runway ends

Contact the City of Jacksonville Planning department to determine whether your property is within an AICUZ zone before planning any ADU project.

Camp Lejeune Water Contamination — Background

From 1953 to 1987, Camp Lejeune's on-base water supply was contaminated with hazardous chemicals including TCE, PCE, benzene, and vinyl chloride — affecting an estimated one million people who lived or worked on base. Key points for civilian off-base property owners:

• Civilian off-base properties served by Jacksonville's municipal water system were not part of the contaminated supply system; this contamination was specific to on-base water utilities
• Older private wells in areas near the base boundary should be evaluated by a licensed environmental professional, though contamination of off-base aquifers was not a documented widespread issue
• The Camp Lejeune Justice Act (2022) created a federal compensation mechanism for victims; this does not directly affect off-base property development rules
• If you are purchasing or renovating older residential property near the base perimeter, consider engaging an environmental consultant for due diligence

Permitted ADU Types (Outside AICUZ Restrictions)

For properties not subject to AICUZ restrictions, Jacksonville's UDO generally permits:

• Detached ADU: A separate structure on the same lot as the primary residence
• Attached ADU: An addition connected to the primary structure with its own entrance
• Interior conversion: Converting existing space within the primary dwelling to a separate unit

General Development Standards

Typical ADU standards in Jacksonville (verify current requirements):

• Maximum floor area: Detached ADUs typically limited to 800 sq ft or a percentage of the primary dwelling's floor area
• Setbacks: Side and rear setbacks commonly 5–8 ft; front setback must meet district minimums
• Height: Typically limited to 20–24 ft or the primary dwelling height
• Lot coverage: ADU counts toward total lot and impervious surface coverage limits
• Parking: One additional off-street parking space commonly required

Special Considerations

• Coastal plain flooding: Jacksonville and Onslow County are in the coastal plain; properties near New River, Northeast Creek, and other waterways may be in FEMA Special Flood Hazard Areas
• VA financing: A large proportion of Jacksonville homeowners use VA loans; any rental use or ADU should be verified for compliance with VA loan terms by a qualified lender
• Military service member turnover: The rental market for ADUs near base entrances can be strong due to military family housing demand; confirm Jacksonville's rental licensing requirements

Permit Process

1. AICUZ check: Verify whether your property is in an AICUZ overlay via Jacksonville Planning or the Onslow County GIS portal
2. Jurisdiction confirmation: City of Jacksonville vs. unincorporated Onslow County
3. Zoning verification: Confirm base zoning district and any other overlays
4. Pre-application consultation: Contact Development Services to discuss AICUZ status and UDO requirements
5. Zoning permit application: Submit with site plan
6. Building permit: Submit construction documents for review
7. Inspections: At multiple construction stages
8. Certificate of Occupancy: Required before occupancy

Contact

City of Jacksonville Planning Department 815 New Bridge Street, Jacksonville, NC 28540 Phone: (910) 938-5296 Website: jacksonvillenc.gov/197/Planning

Disclaimer: Zoning regulations and military AICUZ restrictions are subject to change. Always verify current ADU rules, AICUZ overlay status, and flood zone designations directly with the City of Jacksonville Planning department before beginning any project. The Camp Lejeune water contamination issue is a separate matter from civilian property ADU permitting; consult a qualified environmental professional for site-specific environmental questions. This page is for informational purposes only and does not constitute legal or zoning advice.