In Phoenix, an ADU that meets the zoning standards is a permitted use, so it is reviewed by staff without a public hearing. You still need a building permit with a scaled site plan and floor plan. Arizona law defines a permitted use this way for cities over 75,000, though a staff site plan check can still apply.
What goes into the Phoenix submittal?
- Site plan. Drawn to scale, showing every structure, setbacks, easements and the lot coverage math.
- Floor plan. Also to scale; Phoenix uses it to confirm gross floor area against the main home.
- Structural drawings. Foundations sized for the soil, including caliche where we find it.
- Energy compliance. Phoenix's 2024 building codes, including its energy code, took effect August 1, 2025.
- Mechanical and electrical. Cooling load, panel load calculation and service sizing.
Phoenix lists two contacts for ADU questions: its Site Planning team for zoning and its residential building team for building and utility questions. We handle that correspondence for you.
Is it different in Scottsdale?
Yes. As of October 2026, Scottsdale asks for an online pre-application, a pre-application meeting, then a formal administrative application. Construction plans come after the administrative approval. See ADUs in Scottsdale.
What are the fees?
They vary by city and size. Glendale publishes an estimate: about $13,034 for a 1,000 sq ft detached ADU and $12,184 attached, mostly water and sewer impact fees, in its June 30, 2025 handout. Other cities price differently. See ADUs in Glendale.
What does a city have to accept?
For cities over 75,000, Arizona law sets limits on what can be demanded of an ADU, as of October 2026:
- No added parking, and no fee in lieu of parking.
- No side or rear setback over 5 feet.
- No requirement to match the house's design, roof pitch or materials.
- No fire sprinkler requirement and no commercial building code.
- No public street improvements, other than repairing streets damaged by the work.
Building, fire and health codes still apply in full. Read the Phoenix ADU rules for the city's own numbers.
How long until the permit is issued?
It depends on the city's queue, the completeness of the first submittal and how many correction rounds follow. One Phoenix-area builder reports permit issuance typically taking 6 to 10 weeks. You get a project timeline along with the quote.