Everything homeowners need to know about building a Detached Accessory Dwelling Unit (DADU) in Nashville - size limits, setbacks, permits, and the sweeping late-2025 rule change that made them by-right across most of the city's Urban Services District.
Last verified: September 2026
7/10 · Increasingly ADU-friendly
850 sq ft*
Max ADU size
27 ft ridge*
Max height
Required*
Owner-occupancy
By-right (USD)*
Permit type
This page summarizes Detached Accessory Dwelling Unit (DADU) standards under Metro Nashville's zoning code (Title 17), as amended by ordinance BL2025-1007, for general reference - it is not legal advice. Regulations change; always confirm current requirements with the Metro Nashville Planning Department and Codes and Building Safety before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
Lot size
Max size
Max height
Notes
Under 10,000 sq ft
700 sq ft
10 ft eave (1 story) or 17 ft eave (2 story); 27 ft roof ridge max
Footprint cannot exceed the primary structure's footprint
10,000 sq ft and larger
850 sq ft
Same height limits as smaller lots
Must remain visually subordinate to the primary house
Allowed zoning districts
Under BL2025-1007 (approved by Metro Council December 5, 2025, on a 29-8 vote), DADUs are now permitted by-right in most single-family residential zones within Nashville's Urban Services District (USD). In the General Services District (GSD), a DADU generally still requires a DADU overlay approved through Metro's rezoning process rather than being available by right. Confirm your parcel's district and overlay status with the Planning Department before designing.
Additional standards
Setbacks, parking & other rules
Setbacks
Rear: minimum 3 ft (10 ft if a garage or carport faces an alley). Side: half of the zoning district's standard side setback, minimum 3 ft, for DADUs of 850 sq ft or less; larger structures must meet the full zone setback. Cannot be built over easements or platted setback lines
Parking
Off-street parking is required; the substitute ordinance that passed in December 2025 increased the parking requirement from earlier drafts of the bill. Confirm the current space count with Metro Codes for your specific zone
Units per lot
1 DADU maximum per parcel that has only one principal structure on it
Owner-occupancy
Required. One of the two dwellings on the lot (the primary house or the DADU) must be owner-occupied, and the DADU must be owned by the same person who owns the principal structure
Short-term rentals
A DADU newly built under the base by-right allowance in a single-family (RS) zone cannot obtain an owner-occupied short-term rental permit - a restriction added in the final version of BL2025-1007
Building code
Must meet the applicable Metro-adopted residential building code, verified through standard framing, plumbing, electrical, and final inspections
Ordinance history
How Nashville's DADU rules got here
2011Historic-overlay DADUs first expanded. An early ordinance broadened where detached accessory dwelling units could be built within certain historic overlay districts.
2015The DADU Overlay District is created. Ordinance BL2015-1120 established a formal DADU Overlay process, letting property owners petition Metro Council to rezone an individual parcel to allow a detached accessory dwelling unit - a case-by-case, discretionary path rather than a by-right one.
2025BL2025-1007 passes. After a public hearing that November, Metro Council gave final approval on December 5, 2025, by a 29-8 vote with one abstention, extending DADUs by-right across most Urban Services District residential zones and retiring the old case-by-case overlay-petition requirement for those areas. A late amendment scaled the size cap back to 850 sq ft on larger lots and added the owner-occupied short-term-rental restriction in RS zones.
Worth knowing: this reform passed as part of a broader package of zoning bills responding to Nashville's rapid population growth (now roughly 746,000 residents, the largest city in Tennessee) and a median home price that has climbed toward the $500,000 range by mid-2026. Metro Planning is required to report back on permits, units added, and infrastructure costs from the new rules by the end of April 2027.
Permit process
How Nashville DADU permitting works
1
Confirm your zoning and overlay status
Check whether your parcel is in the Urban Services District (by-right in most residential zones) or the General Services District (generally requires a DADU overlay) with Metro Planning.
2
Prepare your plan set
You'll need a Residential Permit Application, a site plan showing distances to property lines and easements, four-corner elevations, and a floor plan showing the interior layout and fixtures.
3
Submit to the Zoning Help Desk
A registered contractor submits the application; a zoning examiner reviews the plans against the DADU standards and returns an agency checklist.
4
Obtain other agency sign-offs
Work through any additional department reviews flagged on the checklist (for example stormwater or historic zoning, where applicable).
5
Pay permit fees and schedule inspections
Once the permit issues, build and schedule the standard construction inspections.
6
Record ownership and occupancy documentation
Be ready to document that the DADU is owned by the same person as the principal structure and that one of the two dwellings is owner-occupied.
Contact Metro Codes and Building Safety at 615-862-6500 (Metro Office Building, 800 President Ronald Reagan Way) for current fees and review timelines.
Budgeting
What it costs to build a DADU in Nashville
Garage conversion
Roughly $65,000-$170,000, depending on the existing structure's condition
New detached ADU
Roughly $140,000-$300,000 for a code-compliant, freestanding 700-850 sq ft unit
Permit & inspection fees
Confirm the current fee schedule with Metro Codes and Building Safety
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends on lot conditions, finishes, and whether utilities need to be extended to a detached structure. Nashville's construction costs run more moderate than many coastal and West Coast markets, though rapid regional growth has been pushing labor and materials costs up in recent years.
Before you apply
Tips for a smooth approval
Confirm USD vs. GSD status before you design. Whether your DADU is by-right or needs a discretionary overlay rezoning depends entirely on which services district and zone your parcel sits in.
Plan around the owner-occupancy requirement. One of the two dwellings must be owner-occupied and the DADU must share ownership with the main house - this rules out a pure rental-investment DADU on someone else's lot.
If short-term rental income is part of your plan, check the RS-zone restriction first. A newly built by-right DADU in a single-family zone cannot get an owner-occupied short-term rental permit under the final 2025 ordinance.
Keep the footprint at or under the primary structure's footprint. It's a hard cap, not just a guideline, and it interacts with the separate 700/850 sq ft floor-area limit.
Confirm the current parking requirement directly with Metro Codes. It was increased late in the legislative process, and the exact space count depends on the substitute ordinance's final language for your zone.
FAQ
Common questions
Do I need to live on the property to build a DADU in Nashville?
Yes. One of the two dwellings on the lot, either the primary house or the DADU, must be owner-occupied, and the DADU must be owned by the same person as the principal structure.
Is a DADU allowed by right, or do I need a rezoning?
It depends on your parcel. Since BL2025-1007 passed in December 2025, DADUs are by-right in most residential zones within the Urban Services District. In the General Services District, most parcels still need a discretionary DADU overlay approved through Metro's rezoning process.
How many DADUs can I build on one lot?
One, and only on a parcel that has just one principal structure on it.
What's the maximum size for a DADU in Nashville?
700 sq ft on lots under 10,000 sq ft, or 850 sq ft on lots of 10,000 sq ft or larger, and the DADU's footprint can't exceed the primary structure's footprint.
How tall can a Nashville DADU be?
Eave height is capped at 10 ft for a single story or 17 ft for two stories, with an overall roof ridge maximum of 27 ft measured from average finished grade. It must also stay visually subordinate to the primary house.
Do I need parking for a DADU?
Yes, off-street parking is required. The requirement was increased in the substitute ordinance that passed in December 2025 - confirm the current space count for your zone with Metro Codes.
Can I rent my DADU out on Airbnb or a short-term rental platform?
Not if it's a newly built DADU in a single-family (RS) zone using the base by-right allowance - those units are barred from getting an owner-occupied short-term rental permit. Properties in other zones (R, RM, or mixed-use/commercial districts) may still qualify; confirm with Metro Codes.
How much does a DADU cost to build in Nashville?
Garage conversions tend to run roughly $65,000-$170,000, and new detached units roughly $140,000-$300,000, based on local contractor estimates and regional reporting - not counting permit fees.
Does Tennessee have a statewide ADU law?
No. Unlike some other states, Tennessee's legislature has not passed a statewide ADU mandate as of this writing. DADU rules in Nashville are set entirely by Metro's own zoning code, which is why they look different from a nearby county's rules.
