ADU Rules in Franklin, Tennessee

Franklin, seat of Williamson County, is one of Tennessee's most affluent and fastest-growing cities, located approximately 20 miles south of Nashville. With a population exceeding 85,000, Franklin combines a nationally recognized historic downtown district with significant new residential development on its suburban periphery. The city sits on the grounds of the Battle of Franklin (November 30, 1864), one of the Civil War's most devastating engagements, and historic sites including the Carter House and Carnton Plantation draw visitors year-round.

No Statewide ADU Law in Tennessee

Tennessee has not enacted statewide ADU preemption legislation. Franklin's Planning Department administers the local zoning ordinance, which is the controlling document for all ADU-related questions within city limits.

What ADUs Are Permitted

Franklin's zoning ordinance allows accessory dwelling units in residential districts. The city uses a land use chart approach that specifies where ADUs are permitted by right versus by special exception. Common ADU types include:

• Detached ADUs — freestanding structures, including garage apartments, in the rear yard
• Attached ADUs — additions sharing a wall with the primary residence
• Internal conversions — basement or above-garage units within the existing dwelling structure

Size, Setbacks, and Height

ADU standards in Franklin vary by zoning district. General parameters include:

• Maximum size: ADU size is typically capped as a percentage of the primary dwelling's gross floor area or at an absolute square footage limit; confirm current limits in the Code of Ordinances
• Setbacks: Standard zone setbacks apply; detached ADUs must maintain minimum distances from property lines, with alley-adjacent lots sometimes benefiting from reduced rear setbacks
• Height: Detached ADUs are generally limited to one or two stories; height is measured and capped consistent with accessory structure rules in the base zone

Historic District Overlay — HARB Review

Franklin's Historic District encompasses the core of the original town and extends into several adjacent residential neighborhoods containing Civil War-era and Victorian-era architecture. The Historic Architectural Review Board (HARB) has jurisdiction over:

• Exterior alterations to contributing structures within the historic overlay
• New construction (including ADUs) in the historic overlay that would be visible from the public right-of-way
• Demolition of contributing structures

If your property lies within the historic overlay, HARB review is typically required before a building permit for an ADU can be issued. The process involves presenting design drawings to the HARB, which evaluates compatibility with the historic character of the district. Allow additional time for HARB review in your project timeline.

HOA Restrictions

A high proportion of Franklin's newer residential subdivisions are governed by HOAs with CC&Rs (Covenants, Conditions, and Restrictions) that may prohibit or restrict ADU construction — for example, by prohibiting secondary kitchens, limiting outbuilding size, or requiring architectural committee (ACC) approval for any new structures. CC&R restrictions are enforceable even when zoning permits an ADU. Always review your HOA documents before committing to ADU development.

Permit Process

1. Verify zoning and historic overlay status — Use Franklin's online zoning map or call (615) 550-6657
2. Review HOA CC&Rs — Confirm no deed restrictions prohibit ADU construction
3. HARB pre-application (if applicable) — Contact the Planning Department to schedule a pre-application meeting if your property is in the historic overlay
4. Prepare construction documents — Retain a licensed architect or designer; design must meet HARB guidelines if in historic overlay
5. Submit building permit — Apply through Franklin's Building and Neighborhood Services Department
6. Inspections and CO — Pass required inspections before occupying the ADU

Contact Information

City of Franklin Planning Department 109 Third Avenue South, Suite 160, Franklin, TN 37064 Phone: (615) 550-6657 Website: franklintn.gov/government/departments-programs/planning-sustainability

Franklin Building and Neighborhood Services 109 Third Avenue South, Franklin, TN 37064 Phone: (615) 550-6654

Disclaimer: This page provides general information only and is not legal advice. Franklin's zoning code and historic overlay requirements are subject to amendment. Always verify current ADU regulations with the Franklin Planning Department and confirm HOA restrictions before making any development decisions.