ADU Rules in Nashville, Tennessee

Nashville — officially Metro Nashville-Davidson County — is Tennessee's state capital and one of the fastest-growing major cities in the United States. The consolidated city-county government (in place since 1963) administers a single zoning ordinance covering all of Davidson County. Nashville's extraordinary growth has created a serious housing affordability crisis, driving significant interest in accessory dwelling units (ADUs) as a way to add gentle density to established neighborhoods.

No Statewide ADU Law in Tennessee

Tennessee has not enacted statewide ADU preemption legislation. Unlike California, Oregon, or Maine — which have removed local barriers to ADU construction — Tennessee municipalities retain full authority to set their own ADU rules. In Nashville, that means Metro Nashville's local zoning ordinance is the controlling document for all ADU-related questions.

What ADUs Are Permitted

Nashville's zoning code allows ADUs — sometimes called accessory apartments or secondary dwelling units — in residential zoning districts, including the RS (single-family residential) series and some RM (multi-family) and mixed-use zones. Common permitted ADU forms include:

• Detached ADUs — freestanding structures behind or beside the primary home
• Attached ADUs — additions connected to the main dwelling
• Internal/Garage Conversion ADUs — basement apartments or garage conversions within existing structures

Size, Setbacks, and Height

Metro Nashville's zoning ordinance sets ADU parameters at the district level, so exact dimensions depend on your specific zone designation. General guidelines that have historically applied include:

• Maximum size: ADU square footage is typically capped relative to the primary structure; verify current limits in the municipal code
• Setbacks: Rear and side setback requirements apply; detached ADUs must maintain separation from property lines consistent with the underlying zone
• Height: Detached ADUs are generally limited in height; two-story ADUs may require additional review

Always confirm current numerical standards with Metro Nashville Planning, as zoning text amendments are frequent given Nashville's active development environment.

Flood Zone Considerations

A significant portion of Nashville sits within or adjacent to FEMA flood zones tied to the Cumberland River and its tributaries. The May 2010 flood was a historic event that reshaped flood mapping throughout Davidson County. Properties in Special Flood Hazard Areas (SFHAs) must:

• Elevate finished floor elevations above the Base Flood Elevation (BFE)
• Obtain a floodplain development permit from Metro Water Services in addition to a building permit
• Comply with Metro Nashville's floodplain management regulations

Historic and Overlay Districts

Nashville has numerous historic overlay districts covering neighborhoods like East Nashville, Germantown, and 12 South. Properties within Historic Preservation Overlay (HPO) zones may need Metro Historical Commission review before an ADU can be constructed, particularly if exterior alterations to a contributing structure are involved.

Permit Process

1. Verify zoning — Use Metro Nashville's online parcel viewer or call (615) 862-7150
2. Pre-application meeting — Recommended for detached ADUs; Metro Planning staff can clarify overlay requirements
3. Building permit application — Submit to Metro Codes Administration with full construction documents
4. Inspections — Framing, mechanical, electrical, plumbing, and final inspections required
5. Certificate of Occupancy — Required before the ADU can be occupied

Contact Information

Metro Nashville Planning Department Metro Office Building, 800 Second Avenue South, Nashville, TN 37210 Phone: (615) 862-7150 Website: nashville.gov/departments/planning

Metro Codes Administration (Building Permits) 800 Second Avenue South, Nashville, TN 37210 Phone: (615) 862-6500

Disclaimer: This page provides general information only and is not legal advice. Nashville's zoning code is frequently amended. Always verify current ADU regulations with the Metro Nashville Planning Department or review the official Metro Code of Ordinances before making any development decisions.