ADU (Accessory Dwelling Unit) permit in Plano, TX
Yes — you need a permit for adu (accessory dwelling unit) work in Plano.
Building a garage apartment, casita, or other accessory dwelling unit needs a permit. It is new construction of a habitable dwelling unit. R105.2 exempts only a one-story detached accessory structure of 120 square feet or less; an ADU is far larger and habitable, so it is not exempt.
| Permit needed? | Yes |
|---|---|
| Where the line falls | Building a garage apartment, casita, or other accessory d… |
| Fee | You pay the permit fee set in the City of Plano building inspections fee schedule adopted by the city council. The ordinance does not print a dollar amount. |
| Review time | Not in the ordinance |
| Code section | IRC Section R105.2 as amended (Sec. 6-710), Building item 1 — accessory structures over 120 sq ft not exempt; new dwelling unit |
| Based on | IRC 2024 as adopted and amended by the city (Sec. 6-709, Ord. No. 2025-6-15) |
How to pull the permit
- Put together a site plan showing where the work goes, with dimensions.
- Apply through the Plano 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
Building without a required permit is a violation, and every day it continues counts as a separate offense.
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 |
|---|---|---|---|
| Plano | — | Yes | Building a garage apartment, casita, or other accessory d… |
| Richardson | 6 mi | Yes | No size threshold in the code |
| Allen | 6 mi | Yes | No size threshold in the code |
| McKinney | 11 mi | Yes | No size threshold in the code |
| Lewisville | 13 mi | Yes | No size threshold in the code |
| Mesquite | 22 mi | Yes | New accessory dwelling unit; also requires a Conditional … |
Other work in Plano
Questions people ask
How much does a adu (accessory dwelling unit) permit cost in Plano?
You pay the permit fee set in the City of Plano building inspections fee schedule adopted by the city council. The ordinance does not print a dollar amount.. Valuation-based fees mean the number depends on what the job is worth, so the department quotes it when you apply.
I already built it without a permit. What now?
Plano 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.