ADU (Accessory Dwelling Unit) permit in Mesa, AZ
Yes — you need a permit for adu (accessory dwelling unit) work in Mesa.
Building an accessory dwelling unit (a casita, garage apartment, carriage house, or cottage) needs a building permit plus zoning approval. An ADU is a habitable dwelling unit, not one of the small detached accessory structures Mesa lets you skip a permit for (only one-story tool/storage sheds and playhouses up to 200 square feet are exempt, 4-1-4(B)(1)(a)). New residential construction is therefore not exempt: it requires a building permit under Title 4, with zoning compliance under Mesa Zoning Ordinance 11-31-3 (Accessory Dwelling Unit).
| Permit needed? | Yes |
|---|---|
| Where the line falls | Building an accessory dwelling unit (a casita, garage apa… |
| Fee | The code does not print a dollar amount. Building and planning fees come from the City of Mesa fee schedule (4-1-8; 11-56-4 references the Planning Division fee schedule). |
| Review time | Not in the ordinance |
| Code section | 11-31-3 (Accessory Dwelling Unit); building permit per 4-1-4 |
| Based on | Mesa Zoning Ordinance, Title 11 (11-31-3 Accessory Dwelling Unit), with the building permit under the Mesa Administrative Code, Title 4 Chapter 1, and the 2024 IRC adopted as the Mesa Residential Code |
How to pull the permit
- Put together a site plan showing where the work goes, with dimensions.
- Apply through the Mesa 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
Doing work without a required permit triggers a separate permit at regular fees plus an investigation fee (4-1-8); Chapter 4 violations are subject to the penalties in 4-1-9.
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 |
|---|---|---|---|
| Mesa | — | Yes | Building an accessory dwelling unit (a casita, garage apa… |
| Gilbert | 6 mi | Yes | Plan on a building permit (plus electrical, plumbing, and… |
| Chandler | 11 mi | Yes | Building an accessory dwelling unit (a casita, garage apa… |
| Tempe | 12 mi | Yes | Building an accessory dwelling unit (garage apartment, ca… |
| Scottsdale | 21 mi | Yes | Plan on a building permit plus zoning approval to build a… |
| Glendale | 29 mi | Yes | Building an accessory dwelling unit (garage apartment, ca… |
See every Arizona city on adu (accessory dwelling unit) work
Other work in Mesa
Questions people ask
How much does a adu (accessory dwelling unit) permit cost in Mesa?
The code does not print a dollar amount. Building and planning fees come from the City of Mesa fee schedule (4-1-8; 11-56-4 references the Planning Division fee schedule).. 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?
Mesa 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.