Building an ADU in Tennessee

Tennessee has no statewide ADU law

No Tennessee law makes cities or counties allow ADUs. The bill that would have done so in 2026 did not pass. Your city's or county's zoning code decides whether you can add a backyard cottage, garage apartment or other second unit, and on what terms.

The zoning power itself comes from state law. Tennessee Code section 13-7-101 lets a county's legislative body regulate "the location, height and size of buildings" and the uses of buildings and land in the parts of the county outside cities. Section 13-7-201 gives a city's legislative body similar power inside city limits.

The Tennessee Advisory Commission on Intergovernmental Relations (TACIR), a state commission, wrote in its 2024 housing report that zoning "is one power that local governments in Tennessee already have." It said state law preempts local governments on a few matters, such as inclusionary zoning and rent control, "but otherwise local governments have broad authority over their own land use."

Rules vary from place to place. Start with your city's or county's planning or codes department. If you live in Nashville, see the section on Metro Nashville below. [1][2][3]

The 2026 ADU bill that stalled: HB 2031 / SB 2131

HB 2031 and its Senate twin SB 2131 were filed in January 2026 "relative to accessory dwelling units." The House bill was deferred twice in the Cities & Counties Subcommittee and then "taken off notice" on March 11, 2026. The Senate bill was sent to a general subcommittee on March 10, 2026. Neither passed, and neither is law.

As filed, the bill would have barred local rules that, among other things:

• require an ADU to be smaller than 850 sq ft;
• require the owner to live in the main home;
• stop the owner from leasing the ADU;
• require parking for an ADU on a lot under 7,000 sq ft;
• require side or rear setbacks of more than five feet.

It would also have required a permit decision within 60 days, with the permit "deemed approved" if the local government missed that deadline. None of these limits apply to your city or county unless a future law enacts them. [1][4]

Earlier bills and the state's 2024 housing report

In 2024, HB 2292 / SB 2124 would have required each city and metropolitan government to adopt at least four of 12 housing strategies by July 1, 2025. One option was allowing "at least one internal or detached accessory dwelling unit" on a lot with a home used as a primary residence. The bill stalled in committee.

Another 2024 bill, HB 2423 / SB 2237, would have let a city or county that adopted zoning reforms, such as allowing at least one ADU on single-family lots with a home, receive a share of state recordation tax revenue. It was taken off notice in March 2024.

TACIR's May 2024 report, "Reducing the Burden: Increasing Housing Supply to Lower Housing Costs," lists allowing at least one ADU on single-family lots as one of its sample zoning reforms. It said local governments "should retain" land use authority, but that the state could offer guidance and incentives. [2][5][6]

Development review deadlines from 2027: HB 2552

HB 2552, Public Chapter 1044 of 2026, takes effect January 1, 2027. It applies to a municipality, county or metropolitan government "responsible for reviewing a development application, development plan, or a site inspection submitted by a developer."

Within 60 business days of the submission, the local government must either approve it or put it on the next available planning commission or governing body agenda. Alternatively, within 30 business days, it can send a written report of deficiencies or ask for more information. If it does none of these in time, the submission "is deemed approved." It may issue no more than two written reports of deficiencies.

The law does not mention ADUs or say whether it covers a homeowner's building permit. Ask your local codes or planning office how it applies to your project. [7][8]

Nashville: detached accessory dwelling units (DADUs)

Metro Nashville and Davidson County calls a backyard ADU a detached accessory dwelling unit (DADU). Ordinance BL2025-1007, effective December 12, 2025, rewrote the DADU rules and lets DADUs be allowed with conditions in single-family (RS) zones across the Urban Services District.

Under Metro Codes' DADU page, a parcel must be in the Urban Services District, in a DADU overlay in the General Services District, or in an Urban Design Overlay or Specific Plan with DADU standards. Key rules in the code as amended:

• One DADU per lot, and only when one single-family home is on the lot.
• Since May 1, 2026 (ordinance BL2026-1257), a DADU may also go on a legally created lot that is smaller than its zone's minimum lot area, if the lot has at least 3,750 sq ft. Metro Codes' DADU page, last updated in December 2025, still says the lot must meet the zone's minimum lot area, so confirm with the Zoning Help Desk.
• Living space up to 700 sq ft on lots under 10,000 sq ft, or 850 sq ft on lots of 10,000 sq ft or more, and no bigger than the main house.
• It must sit behind the main house; eave height up to 10 feet (one story) or 17 feet (two stories), and the roof ridge lower than the main house's and no more than 27 feet.
• The DADU must be owned by the same person or entity as the main house, and "one of the two dwellings shall be owner-occupied." A covenant must be recorded before the permit is issued.
• One parking space for a DADU (no maximum in the Urban Zoning Overlay).
• Owner-occupied short-term rental is not a permitted use in a new DADU on a single-family, Residential Neighborhood or Residential Limited lot.

Metro Codes says a property owner can't pull a self-permit to build a DADU or convert a garage into one; a registered contractor must apply. Check your zoning in the Parcel Viewer and call Metro Codes at 615-862-6500. [9][10][11][12]

What to check with your city or county

Because the rules are local, ask your planning, zoning or codes office:

• Which zones allow an ADU, and the minimum lot size.
• The maximum ADU size, height and setbacks.
• Whether the owner must live on the property.
• How many parking spaces you need.
• Whether you can rent the ADU short term.
• Permit, plan review and utility connection fees.
• Whether a licensed contractor must pull the permit.

Our ADU permit process guide, garage conversion guide, ADU cost guide and tiny house guide cover the general steps. [2][9]

Tennessee laws to know

• HB 2031 / SB 2131 (2026), proposed ADU law (did not pass)

  Would have barred local rules that cap ADUs below 850 sq ft, require owner occupancy or require parking on lots under 7,000 sq ft, and set a 60-day permit deadline; it never left committee. [1][4]

• HB 2552 (2026), Public Chapter 1044

  From January 1, 2027, sets deadlines for local governments to act on development applications, plans and site inspections; it does not mention ADUs. [7][8]

• HB 2292 / SB 2124 (2024), housing strategies menu (did not pass)

  Would have made cities adopt at least four of 12 housing strategies, one of them allowing an ADU on a lot with a home; it stalled in committee. [5]

Questions people ask