ADU (Accessory Dwelling Unit) permit in Smyrna, TN
Yes — you need a permit for adu (accessory dwelling unit) work in Smyrna.
Building an accessory dwelling unit (garage apartment, casita, etc.) requires a permit. It is a habitable structure well above the 100 sq ft detached-accessory-structure exemption and is not on the R105.2 exempt list.
| Permit needed? | Yes |
|---|---|
| Where the line falls | Building an accessory dwelling unit (garage apartment, ca… |
| Fee | Not in the ordinance — the department quotes it |
| Review time | Not in the ordinance |
| Code section | IRC R105.2 (§ 12-601); detached accessory structure exemption limited to 100 sq ft (§ 12-602 item 1) |
| Based on | IRC 2024 as amended (Town of Smyrna, TN, Ord. No. 26-13) |
How to pull the permit
- Put together a site plan showing where the work goes, with dimensions.
- Apply through the Smyrna building department.
- Pay the permit fee when the permit is issued. Work done before that isn't covered.
- Book each inspection listed on the permit as the job reaches that stage.
If you skip it
It is unlawful to violate or fail to comply with any provision of the residential code as adopted; a violation is punishable under the general penalty provision and each day an offense continues is a separate violation.
Nearby cities, same job
Rules stop at the city line. If your lot is near a boundary, or you work across several towns, this is where they differ.
| City | Distance | Permit? | Where the line falls |
|---|---|---|---|
| Smyrna | — | Yes | Building an accessory dwelling unit (garage apartment, ca… |
| La Vergne | 4 mi | Yes | No size threshold in the code |
| Nolensville | 8 mi | Yes | No size threshold in the code |
| Murfreesboro | 10 mi | Yes | A new accessory dwelling unit (garage apartment, casita) … |
| Brentwood | 14 mi | Yes | No size threshold in the code |
| Mount Juliet | 16 mi | Yes | No size threshold in the code |
See every Tennessee city on adu (accessory dwelling unit) work
Other work in Smyrna
- Fence Depends
- Deck Depends
- Shed Depends
- Swimming Pool Depends
- Roof Replacement Depends
- Water Heater Yes
- HVAC Replacement Yes
- Electrical Panel Yes
- Demolition Yes
- Driveway Depends
- Tree Removal —
- Sign —
- Short-Term Rental —
- ADU (Accessory Dwelling Unit) Yes
- Garage Depends
- Basement Yes
- Above-Ground Pool Depends
Questions people ask
I already built it without a permit. What now?
Smyrna can issue a stop-work order and require you to apply after the fact, sometimes with an extra fee. Work that was covered up may have to be opened for inspection. Full walkthrough here.
Does unpermitted work cause problems when selling the house?
Often, yes. A buyer's inspector or the title company may flag it, and lenders can balk at financing a home with open or missing permits. What to do about it.