Which Valley cities the casita law covers

Covered cities

Population: U.S. Census Bureau 2024 estimates as compiled. Price per square foot: Redfin medians, 2026 readings, see the math page for dates. Sources: Census QuickFacts; Redfin.

Unincorporated Maricopa County

Unincorporated Maricopa County (Sun City, Waddell, Wittmann, Rio Verde, New River and other county islands) is covered by the 2025 county law (A.R.S. § 11-810.01). The county adopted its ADU rules on December 10, 2025. The county rules follow the same floor as the city law: one attached and one detached unit, 75% of the main home or 1,000 sq ft, 5-foot rear and side setbacks, no owner-occupancy requirement, long-term rental allowed. Sources: A.R.S. § 11-810.01; county text amendment TA250002.

Smaller towns

The state law does not reach towns under 75,000 residents. Queen Creek (71,867), Paradise Valley, Fountain Hills, Cave Creek, Carefree, Litchfield Park, Tolleson, El Mirage, Youngtown, Guadalupe, Wickenburg and Gila Bend set their own ADU rules. Some are permissive, some are not; we check the current code for your address during the property review.

What is the same everywhere the law applies

• At least one attached and one detached ADU on any lot with a single-family home, as a permitted use (no public hearing, no variance)
• A unit up to 75% of the main home's gross floor area or 1,000 sq ft, whichever is smaller (cities may allow larger)
• A third, detached unit on lots of one acre or more if one unit is deed-restricted affordable
• Separate long-term rental of either the house or the ADU (leases of 90 days or more, or month to month)

And what no covered city may require:

• Owner occupancy, or any family, marital or employment relationship between the owner and the ADU occupant
• Additional parking, or a fee in place of parking
• Matching exterior design, roof pitch or finish materials
• Height, setback, lot-size, coverage or frontage rules stricter than those for the main house
• Rear or side setbacks of more than 5 feet
• Public street improvements beyond repairing what construction damages
• Commercial building codes or fire sprinklers in the ADU

What still differs by city

• Permit fees, impact fees and utility connection fees. These vary by city and by zone inside a city; Phoenix, for example, charges impact fees in its growth areas and not in the established core.
• Plan review time. Each city runs its own queue. Pre-approved plans under the 2026 law should shorten it where cities adopt them.
• Allowances beyond the floor. Phoenix permits larger units on lots over 10,000 sq ft. Other cities stop at the state minimum.
• Short-term rental permits. Separate from the ADU rules and different in every city.
• Utilities. Water and sewer providers differ, and septic areas have their own review.

The same map, read as price per foot

The target areas page ranks every Phoenix neighborhood and Valley city by resale price per square foot against the cost to build, in four tiers.

The resale column is the number that decides whether a casita pays for itself at sale. A new casita builds for about $265 to $280 per finished foot. In Scottsdale, Chandler, Tempe and much of Phoenix, homes already sell for more than that per foot, so the unit is built below the resale rate before rent is counted. In the West Valley, where homes sell for about $190 to $235 per foot, the case rests more on rent and on family use than on resale value. The math page shows the calculation; the rental page shows the other half.