ADU (Accessory Dwelling Unit) permit in Chattanooga, TN
Yes — you need a permit for adu (accessory dwelling unit) work in Chattanooga.
Building a garage apartment, casita, or other accessory dwelling unit needs a building permit. It is new construction of a habitable dwelling unit under the adopted residential/building code; the permit exemption for detached accessory structures only reaches non-habitable buildings 200 square feet or smaller. Zoning rules for accessory dwelling units (entrance placement, one principal building per lot) also apply, but those are placement standards, not the permit trigger.
| Permit needed? | Yes |
|---|---|
| Where the line falls | Building a garage apartment, casita, or other accessory d… |
| Fee | Not in the ordinance — the department quotes it |
| Review time | Not in the ordinance |
| Code section | Sec. 38-43 (Accessory Use Standards); IRC R105/R106 |
| Based on | IRC/IBC 2018 as adopted by City of Chattanooga |
How to pull the permit
- Put together a site plan showing where the work goes, with dimensions.
- Apply through the Chattanooga 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.
Either of you can pull it. When a contractor does the work, it is normally their job.
If you skip it
Chattanooga's code doesn't set a specific fine for this work. In practice the department can issue a stop-work order, and unpermitted work tends to surface during a sale, when the buyer's inspector or the title company asks for it.
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 |
|---|---|---|---|
| Chattanooga | — | Yes | Building a garage apartment, casita, or other accessory d… |
| Farragut | 82 mi | Yes | No size threshold in the code |
| Murfreesboro | 86 mi | Yes | A new accessory dwelling unit (garage apartment, casita) … |
| Smyrna | 95 mi | Yes | Building an accessory dwelling unit (garage apartment, ca… |
| Knoxville | 96 mi | Yes | Building an accessory dwelling unit (garage apartment, ca… |
| La Vergne | 99 mi | Yes | No size threshold in the code |
See every Tennessee city on adu (accessory dwelling unit) work
Other work in Chattanooga
Questions people ask
I already built it without a permit. What now?
Chattanooga 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.