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For years, adding a backyard casita in Phoenix meant wading through special permits and hearings that made the idea more trouble than it was worth. That changed fast. Arizona's legislature rewrote the rules for accessory dwelling units, and Phoenix homeowners now have a legal right to build one, often without the red tape that once stopped projects before they started.
If you own a single-family home in Phoenix and you've been wondering whether a casita could turn into real rental income, here's what the law actually allows, what it still restricts, and what to weigh before you spend a dollar on design or permits.
Key Takeaways
- Arizona's HB 2720 and HB 2928 require Phoenix and most other cities and counties to permit ADUs on single-family lots, largely without special hearings.
- Phoenix allows up to two ADUs per single-family lot, with a third possible on larger parcels if one unit is deed-restricted as affordable housing.
- Arizona eliminated the owner-occupancy requirement statewide in 2023, so you can rent out a long-term ADU without living on the property.
- Phoenix specifically prohibits ADUs from operating as short-term rentals, even though the primary home on the same lot isn't subject to that restriction.
- State law limits what cities can restrict, but HOA rules still apply, and a restrictive CC&R can block an ADU regardless of what the city allows.
What Changed: Arizona's Casita Bill and Its 2026 Expansion
Arizona passed House Bill 2720, widely known as the Casita Bill, in 2024. Signed by Governor Katie Hobbs and effective January 1, 2025, it required cities with populations over 75,000, including Phoenix, to permit accessory dwelling units on single-family lots. Phoenix had already adopted its own ADU ordinance in 2023, but state law required Phoenix to revise its ordinance, loosening several restrictions it had originally imposed.
The following year, HB 2928 expanded the same framework to counties, with a January 1, 2026, deadline for county governments to adopt compliant regulations. Counties that missed that deadline default to allowing ADUs on all residentially zoned parcels without restriction, which gave counties a strong incentive to get their rules in place on time. Together, the two laws mean that homeowners across most of Arizona, not just Phoenix, now have a clear legal path to build a casita.
What Phoenix Actually Allows You to Build
Phoenix regulates ADUs through Zoning Ordinance Section 706, which allows ADUs in single-family residential zones across most of the city. State and city rules together allow two ADUs per single-family detached house, and, in some cases, a third if the parcel is at least one acre and one of the units is deed-restricted for affordable housing.
Size is tiered by lot size. On lots under 10,000 square feet, an ADU is capped at 1,000 square feet. On larger lots, the cap rises to 3,000 square feet or 10% of the net lot area, whichever is smaller. In every case, the ADU can't exceed 75% of the primary home's gross floor area. Setbacks follow the underlying zoning district rather than one citywide number, and the ADU must include its own kitchen, bathroom, and separate utility connections to qualify as a self-contained living space.
Do You Have to Live on the Property?
No, not for a long-term rental. Arizona eliminated the statewide owner-occupancy requirement in 2023, which means you can build an ADU and rent it out on a long-term lease without living in the primary home yourself. That makes Phoenix a workable market for investors and remote landlords, not just owner-occupants adding space for family.
Short-term rentals are a different story. Phoenix specifically prohibits ADUs from operating as short-term rentals through platforms like Airbnb or Vrbo, even though the primary dwelling on the same lot isn't subject to that same restriction. If short-term rental income is part of your plan, that's a meaningful limitation to understand before you build, and it's worth comparing to nearby cities like Scottsdale, where short-term rental rules for ADUs differ.
What an ADU Actually Costs, and What It Can Earn
Cost depends heavily on size, finish level, and site conditions, but a detached casita in the Phoenix metro typically runs $120,000 to $350,000 or more. A garage conversion is usually the cheapest and fastest path, often finished in four to six months, while a new detached structure built from the foundation up typically takes six to ten months from design to certificate of occupancy.
On the income side, a long-term ADU rental adds a second, ongoing stream of income from a property you already own, without the cost of acquiring a second parcel. The exact rent depends heavily on size, finish, and neighborhood, so it's worth running the numbers on your specific property and comparable local rentals before committing to a full build, rather than assuming a nationwide average will apply to your street.
Before You Build: HOA Rules and the Permitting Process
State law is deliberately aggressive about what cities can restrict, but it doesn't touch private HOA covenants. If your property sits inside a homeowners association, the HOA's CC&Rs can still prohibit ADUs, detached structures, or additional dwelling units entirely, regardless of what Phoenix zoning allows. Before spending money on design or permits, pull your HOA's governing documents and get written confirmation of what's permitted on your specific lot. Verbal assurances from a board member aren't enough if a dispute ends up in front of a judge.
Permitting is handled through the city's Shape Phoenix online portal or in person at Phoenix City Hall and requires a site plan and construction drawings that meet zoning and building code requirements. ADUs must also meet the International Residential Code, covering smoke detectors, fire-resistant construction, and clear emergency egress paths, the same baseline safety standards that apply to any other home.
Weighing the Investment: Benefits and Challenges
The upside is real. An ADU adds usable square footage and a second income stream to a property you already own, often for less than the cost of buying a second investment property outright. It can also meaningfully boost resale value, particularly in a market where buyers increasingly expect flexible living space.
The challenges are worth taking seriously too. Construction costs of $120,000 or more are a significant upfront commitment; financing an ADU isn't always straightforward; and the Phoenix short-term rental ban limits one common income strategy that works in other cities. HOA restrictions can also stop a project after you've already spent money on design, so the due diligence has to happen before the first permit application, not after.
Is an ADU the Right Move for Your Property?
An ADU makes the most sense when the numbers pencil out against your specific lot, your specific HOA, and the actual rental demand in your neighborhood, not a generic statewide average. Run your own numbers with our ROI Calculator before committing to a build, and if you're weighing an ADU against other ways to improve returns on an existing rental, our owner resources page is a good place to start.
Frequently Asked Questions
Do I need to live in the main house to rent out an ADU in Phoenix?
No. Arizona eliminated the owner-occupancy requirement statewide in 2023, so you can build and rent out an ADU on a long-term lease without living on the property yourself.
Can I use my Phoenix ADU as an Airbnb?
No. Phoenix prohibits ADUs from being used as short-term rentals, regardless of how the primary home on the same lot is used. Long-term leases are permitted just like any other rental.
How many ADUs can I build on one lot in Phoenix?
Most single-family lots are allowed up to two ADUs. A third may be allowed on lots of at least one acre if one of the units is deed-restricted as affordable housing.
Can my HOA still stop me from building an ADU?
Yes. State and city laws govern zoning, but they don't override private HOA covenants. If your CC&Rs prohibit ADUs or additional structures, the HOA can still deny your request, so check your governing documents before you spend money on design or permits.
What size ADU can I build on my property?
On lots under 10,000 square feet, Phoenix caps ADUs at 1,000 square feet. On larger lots, the cap is 3,000 square feet or 10% of the net lot area, whichever is smaller, and the ADU can never exceed 75% of the primary home's gross floor area.
Turn Your Casita Into a Managed Investment, Not a Side Project
Building an ADU is the easy part compared to renting it out well. Screening a second tenant on your property, keeping rent collection and maintenance organized across two units, and pricing the unit correctly all take real, ongoing attention. Rosenbaum Realty Group helps Phoenix-area owners manage exactly this kind of investment, from tenant screening to accounting, rent collection, and beyond.
If you're thinking about adding a casita or you already have one sitting empty, reach out through our property management services page, and we'll help you figure out what it's actually worth.
