Zoning Guide

ADU Rules in Phoenix, Arizona

Last updated: Verified:

Arizona's casita statute is HB 2720 (2024), codified at A.R.S. §9-461.18, applying to cities with 75,000+ population. HB 2673 is unrelated.

Arizona's casita statute is HB 2720 (2024), codified at A.R.S. §9-461.18, applying to cities with 75,000+ population. HB 2673 is unrelated.

Arizona's casita statute is HB 2720 (2024), codified at A.R.S. §9-461.18, applying to cities with 75,000+ population. HB 2673 is unrelated.

Permitted ADU Types

  • Detached ADU: A standalone structure on the residential lot
  • Attached ADU: An addition to the primary home with its own entrance
  • Garage Conversion: Converting an existing garage to a dwelling unit
  • Internal ADU: Converting space within the existing home

Size Limits

ADU Type Maximum Size
Detached ADU 1,000 sq ft or 50% of primary dwelling
Attached ADU 1,000 sq ft or 50% of primary dwelling
Garage Conversion Existing footprint

Setbacks

  • Front: Must meet base zone standard (typically 20–25 ft)
  • Side: 5 feet minimum
  • Rear: 5–10 feet minimum depending on zone
  • From primary dwelling: No minimum separation required in many zones

Height

  • Detached ADU: Maximum 14 feet for flat lots; up to 20 feet on sloped lots in some zones
  • Cannot exceed height of primary dwelling

Parking

One additional off-street parking space is required per ADU in most Phoenix zones. In some transit-served areas, parking requirements may be waived.

Heat Island and Desert Climate

Phoenix's extreme heat (summer temperatures exceeding 115°F) affects ADU design:

  • Cool roof materials and adequate insulation are important
  • Shade structures are beneficial
  • Water-efficient landscaping required
  • Proper HVAC design for extreme heat is essential

Permit Process

  1. Check zoning: Verify your zone at phoenix.gov/pdd
  2. Design: Prepare architectural plans meeting Phoenix standards
  3. Submit: Apply online through Phoenix's permitting portal
  4. Plan review: Zoning and building code review
  5. Permit issuance: Receive building permit
  6. Inspections: Required at each phase
  7. Certificate of Occupancy: Required before occupancy

Contact

Phoenix Planning & Development Department 200 W. Washington Street, Phoenix, AZ 85003 Phone: (602) 262-7811 Website: phoenix.gov/pdd

Disclaimer: Verify current requirements with the Phoenix Planning & Development Department. Arizona state law may also affect local ADU regulations.

More about Phoenix Zoning

Building Permits — Cost & TimelineSetbacks & Height Limits

Sources

  1. City of Phoenix — Accessory Dwelling Units·phoenix.gov·Accessed 2026-09-20·Direct link
  2. Arizona Revised Statutes §9-461.18 — Accessory Dwelling Units·azleg.gov·Accessed 2026-09-20·Direct link
  3. City of Phoenix — Residential Building·phoenix.gov·Accessed 2026-09-20·Direct link

FAQ

How many ADUs can a Phoenix property have?
Current City of Phoenix guidance says a lot with no more than one single-family detached primary dwelling may have two ADUs in addition to the primary dwelling. A third detached ADU may be permitted on certain lots when the state restricted-affordable ADU condition is met.
How large can a Phoenix ADU be?
Phoenix states that each ADU may be up to 75% of the gross floor area of the main house, with a 1,000-square-foot cap on lots up to 10,000 square feet and a 3,000-square-foot cap on lots larger than 10,000 square feet.
Can Phoenix require extra parking or larger ADU setbacks?
Arizona A.R.S. §9-461.18 prohibits a municipality from requiring additional parking solely for an ADU and generally bars ADU-specific rear or side setbacks greater than five feet, subject to the statute's applicability and exceptions.
Where do I start a Phoenix ADU permit?
Use Phoenix Planning & Development's residential-building resources and SHAPE PHX. The City also maintains an ADU page and is developing preapproved ADU plans.