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ADU in Arizona: New Laws, Rules & Costs by City
Table of Contents
Arizona's 2024–2025 legislation fundamentally changed how backyard accessory dwelling units work across the state. With House Bill 2720 and its county-level expansion through HB 2928, most residential property owners now have a legal pathway to build ADUs in Arizona — though specific rules still vary by city, lot, and HOA.
This guide covers the current legal framework, city-by-city requirements, realistic cost ranges, permitting steps, and rental income considerations. Because ADU regulations in Arizona continue to evolve at the municipal level, confirming current requirements with your local planning department is an important early step.
What Arizona Law Now Requires
Arizona addressed its housing shortage through statewide ADU legislation rather than leaving the issue entirely to individual cities. The result is a two-part legal framework that applies to both municipalities and counties, with specific provisions around short-term rental use.
1. HB 2720 — Statewide ADU Rules for Cities (Effective January 2025)
Signed by Governor Katie Hobbs in May 2024, House Bill 2720 requires every Arizona city with a population over 75,000 to allow accessory dwelling units on single-family residential lots. Understanding the full ADU meaning in real estate context helps clarify why this legislation targets single-family zones specifically.
Under this law, qualifying municipalities must permit at least one attached and one detached ADU per lot as a matter of right — no special use permits, variances, or public hearings required.
For lots one acre or larger, cities must also allow one additional detached ADU, provided at least one unit on the property qualifies as a restricted-affordable dwelling unit — defined as housing for households earning up to 80% of the area median income.
The law caps ADU size at 75% of the primary dwelling's gross floor area or 1,000 square feet, whichever is less. Even a 150 sq ft ADU qualifies under this framework, provided it meets local building code minimums for habitable space. It also establishes a set of restrictions that cities cannot impose. Municipalities may not:
- Require additional parking spaces for an ADU or charge fees in lieu of parking
- Mandate that an ADU match the primary home's exterior design, roof pitch, or materials
- Set rear or side setbacks greater than five feet from the property line
- Impose restrictions on ADUs that are stricter than those applied to single-family homes in the same zoning district
- Require fire sprinklers or apply commercial building codes to an ADU
- Prohibit the use of an ADU as separately leased long-term rental housing
- Require a familial or employment relationship between the primary home occupant and the ADU occupant
- Require improvements to public streets as a condition of allowing an ADU, except where necessary to repair streets disturbed during construction
It is worth noting that ADU rules in Arizona under HB 2720 do not apply to all properties. Lots located on tribal land or within designated proximity to military airports, FAA-licensed commercial airports, general aviation airports, or public airports are excluded from the law's requirements. Property owners in these areas should verify eligibility directly with their local planning department, as ADU zoning classifications vary even within the same county.
This legislation significantly reshaped ADU laws in Arizona by removing many of the local barriers that previously made construction difficult or impossible in major metro areas. Arizona's approach differs from states that allow tiny homes by specifically mandating permanent, site-built or modular structures with full utility connections rather than mobile or wheeled units.
2. HB 2928 — Extending ADU Rules to Counties (2025)
House Bill 2720 applied only to cities over 75,000 in population, leaving a gap for homeowners in unincorporated areas and smaller communities. HB 2928, signed into law on May 23, 2025, addressed this by extending nearly identical ADU requirements to counties across Arizona. Counties must adopt compliant regulations by January 1, 2026, or ADUs will be automatically permitted on all residentially zoned lots without limits — the same default mechanism that applied to cities under HB 2720.
The development standards mirror those established under HB 2720: same size caps, same setback limits, same list of prohibited municipal restrictions. Counties must allow at least one attached and one detached ADU on any lot where a single-family dwelling is permitted, with provisions for an additional affordable unit on parcels of one acre or more.
For property owners outside city limits — particularly in unincorporated parts of Maricopa, Pima, and Pinal counties — this expansion is significant. Previously, county-level zoning in many areas either prohibited accessory units or imposed requirements that made them impractical. HB 2928 creates a consistent baseline that ADU builders in Arizona can work within regardless of whether a property falls inside or outside city jurisdiction. Note that Arizona's legislation applies to permanent structures — ADUs on wheels are governed by different regulatory frameworks and are not covered under HB 2720 or HB 2928.
3. Short-Term Rental Restrictions on Newer ADUs
One often-overlooked provision in the legislation addresses vacation and short-term rental use. For any ADU in Arizona constructed on or after September 14, 2024, cities and counties may require the property owner to reside on the premises if the unit is being used as a short-term or vacation rental.
This owner-occupancy condition applies specifically to short-term rental scenarios — it does not affect long-term leasing arrangements of 90 days or longer. Property owners who had the legal right to build an ADU before September 14, 2024, whether or not construction had begun, are generally exempt from this requirement.
The distinction matters for homeowners evaluating rental strategies. Long-term leasing remains unrestricted under state law, but those planning to list an ADU on platforms like Airbnb or VRBO should confirm whether their city enforces the owner-occupancy provision and how it interacts with any separate short-term rental licensing requirements.
ADU Rules by Arizona City
While state law sets the floor, individual cities have adopted their own ordinances that fill in the details. The practical experience of building an ADU in Arizona depends heavily on which municipality your property falls under. Below is a comparison of how major cities have implemented their ADU rules, followed by notes on each.
City | Max ADU Size | Setbacks (Rear/Side) | ADUs Allowed Per Lot | Owner-Occupancy | Notable Details |
Phoenix | 75% of primary or 1,000 sq ft (lots ≤10,000 sq ft); up to 3,000 sq ft or 10% of net lot area on larger lots | 5 ft min. from side property line | 2 (attached + detached); 3rd on 1-acre+ lots | Not for long-term rental | Detached ADU can be in the required rear yard; typically 15 ft height unless a use permit allows more. |
Tucson | 75% of primary or 1,000 sq ft; minimum 650 sq ft guaranteed on all lots | 5 ft min. | 2; 3rd on 1-acre+ with affordable unit | Not for long-term rental | Cool roof required for new ADUs; added review in certain overlays/historic areas can apply. |
Tempe | 75% of primary or 1,000 sq ft (lots under 1 acre); up to 2,000 sq ft on 1-acre+ lots | 5 ft min. | 2; additional on 1-acre+ with affordable unit | Not for long-term rental | ADU Standard Plan Library (AARP-backed) supports faster/cheaper permitting; cited plan savings range $2k–$6k. |
Mesa | 75% of primary or 1,000 sq ft | 5 ft min. | Per HB 2720 standards | Not for long-term rental | City provides lot-specific guidance and notes HOA/CC&R rules can still restrict ADUs. |
Scottsdale | 1st ADU: 1,000 sq ft or 75% of primary; 2nd and 3rd ADU: 500 sq ft max | 5 ft min. for detached ADUs in rear yard | 2; 3rd on 1-acre+ with affordable unit | Required if ADU is used as STR | Adopted Ordinance 4687 (Sept 2025); separate electrical and gas metering required; max 6 adults total across all dwellings on lot |
Flagstaff | 75% of primary or 1,000 sq ft; minimum 800 sq ft guaranteed | 5 ft rear/side for detached | Per HB 2720 standards | Required if ADU is used as STR | Max 2 occupants per ADU; utilities rules differ by ADU type (attached/interior vs detached). |
1. Phoenix
Phoenix adopted its initial casita ordinance in September 2023, then revised it after HB 2720 took effect. The most significant local distinction is the size allowance on larger lots: properties with a net lot area exceeding 10,000 square feet can build ADUs up to 3,000 square feet or 10% of the lot — substantially beyond the standard 1,000-square-foot cap. The city also previously banned ADU use as short-term rentals, but that restriction was removed under state preemption.
2. Tucson
Tucson's 650-square-foot minimum guarantee benefits homeowners with smaller primary residences who might otherwise be limited by the 75% calculation. The city also requires cool roofs on new ADUs, reflecting local climate policy. Properties in historic or neighborhood preservation zones undergo additional design review, though ADUs in those areas are not required to replicate the primary home's appearance.
3. Tempe
Tempe offers one of Arizona's few pre-approved standard plan programs, developed through an AARP-funded Design Challenge. Selecting a pre-approved plan can bypass portions of plan review and save $2,000–$6,000 in design and review costs. For homeowners evaluating ADU builders in Arizona, Tempe's approach is a useful benchmark for what streamlined permitting can look like.
4. Scottsdale
Scottsdale's ordinance, adopted in September 2025 under HB 2928, stands out for its stricter controls on multi-unit properties. The 500-square-foot cap on second and third ADUs is notably more restrictive than other cities, and the requirement for separately metered electrical and gas connections adds to upfront project costs. The six-adult total occupancy cap across all dwellings on a lot is also unique among major Arizona cities.
5. Flagstaff
Flagstaff caps ADU occupancy at two persons per unit and requires attached or interior ADUs to share utility connections with the primary dwelling — exceptions apply only for internet, television, and telephone. Short-term rental use requires the property owner to reside on-site.
6. Unincorporated Areas and Smaller Cities
For properties outside these cities — particularly in unincorporated Maricopa, Pima, or Pinal counties — HB 2928 provides a consistent baseline with a January 1, 2026 compliance deadline. Cities under 75,000 population are not required to adopt ADU rules in Arizona under current law, though some may do so voluntarily. Property owners in these areas should contact their county planning department to confirm what applies to their specific parcel.
ADUs and HOAs in Arizona: Where State Law Stops
A common misunderstanding about ADU laws in Arizona is that statewide legislation overrides HOA restrictions. It does not.
Both HB 2720 and HB 2928 explicitly preserve the enforceability of restrictive covenants between private parties. If your HOA's CC&Rs or design guidelines prohibit accessory dwelling units or additional detached structures, the association can deny your request — regardless of what city zoning allows.
Where governing documents are silent on ADUs or generally permit accessory structures, the situation is less clear-cut. Arizona case law suggests that a design review committee cannot deny an ADU request without a legitimate, documented reason when the guidelines do not explicitly prohibit one. Arbitrary refusals in that context may be legally challengeable.
The legislation does offer one related protection: municipalities cannot require a homeowner to adopt a restrictive covenant as a condition of receiving an ADU permit. But covenants that already exist within your HOA remain fully enforceable.
For anyone planning to build an ADU in Arizona within an HOA-governed community, reviewing the association's governing documents should be the first step — before engaging architects, contacting ADU builders in Arizona, or submitting permit applications. A conversation with the HOA's architectural review committee early in the process can prevent costly surprises later. If the documents are ambiguous, consulting with a real estate attorney familiar with Arizona community association law is a reasonable precaution before committing project funds.
What It Costs to Build an ADU in Arizona
The ADU cost construction in Arizona varies significantly based on project type, lot conditions, and finish level. The ranges below reflect 2025–2026 pricing trends across the state, with Phoenix metro projects typically landing toward the upper end due to higher labor and material costs.
- Cost by ADU Type
Project Type | Cost Per Sq Ft | Typical Size | Estimated Total Project Cost |
Garage or interior conversion | $150–$250/sq ft | 400–600 sq ft | $70,000–$160,000 |
Prefab or manufactured ADU | $180–$300/sq ft | 400–800 sq ft | $140,000–$300,000 (installed) |
Detached site-built (standard) | $250–$400/sq ft | 600–1,000 sq ft | $150,000–$300,000 |
Detached site-built (custom) | $350–$550+/sq ft | 600–1,000 sq ft | $250,000–$400,000+ |
Total project cost includes foundation, utility connections, permitting, and finishing — not just the structure itself. Prefab ADU cost often appears lower at the unit level, but transportation, crane setting, foundation work, and local code compliance add materially to the final number.
- Additional Costs to Budget For
Item | Typical Arizona Range |
Architectural and design plans | $3,000–$10,000 |
Structural engineering | $1,500–$4,000 |
Permits and plan review fees | $5,000–$10,000+ |
Sewer or water connection | $5,000–$20,000 |
Electrical service upgrade | $2,000–$8,000 |
Site grading and prep | $1,000–$6,000 |
Separate utility metering (where required) | $2,000–$5,000 |
In cities like Scottsdale, where separate electrical and gas metering is mandatory, utility costs will be higher than in municipalities that allow shared connections. Choosing the right ADU appliances for these independently metered units also affects long-term operating costs.
Tempe's pre-approved plan program can reduce design and review expenses for homeowners who select a standard plan. These kinds of city-level differences make it worth comparing local requirements before finalizing a budget.
- Prefab vs. Site-Built
Both approaches are viable under current ADU rules Arizona cities have adopted, but they carry different trade-offs. Prefab units offer more predictable unit pricing and faster factory build times, though the overall project timeline — including permitting, transport, and site work — is often comparable to site-built.
A key financing consideration: some lenders do not classify manufactured or modular structures as real property, which can limit access to conventional loans, HELOCs, or construction financing. Site-built ADUs generally qualify for a broader range of loan products.
Regardless of method, homeowners should expect the full timeline from design through certificate of occupancy to run approximately six to eighteen months, depending on project complexity and city review workloads. Vetting ADU companies early in the planning stage reduces the risk of delays caused by contractor unfamiliarity with local code requirements.
Is Building an ADU in Arizona Worth the Investment?
Whether an ADU makes financial sense depends on location, unit size, and rental strategy. In the Phoenix metro area, sustained population growth and strong rental demand create favorable conditions — but the numbers still need to work for your specific property and budget.
- What Can You Charge?
Average rent in Phoenix currently sits around $1,474–$1,939 per month depending on unit type and neighborhood. A well-finished ADU in the 500–800 square foot range can reasonably command $1,200–$1,800 per month as a long-term rental, with higher figures possible in desirable neighborhoods or for larger units. Short-term rental rates run higher per night but come with additional management overhead and, for ADUs built after September 14, 2024, potential owner-occupancy requirements.
- Rough ROI Math
One Phoenix-area builder estimates construction costs at roughly $350 per square foot in neighborhoods where property values sit around $500 per square foot. Under that scenario, a 600-square-foot ADU costing approximately $210,000 to build could add up to $300,000 in property value — representing around $90,000 in immediate equity gain before rental income is factored in. Thoughtful ADU interior choices — layout efficiency, finish quality, and storage — directly influence where a unit falls within that rental range.
On the rental side, $1,400 per month in long-term rent produces $16,800 annually. Against a $210,000 investment, that's approximately an 8% annual return — with the break-even point falling roughly in the seven-to-ten-year range. Actual returns will vary based on vacancy rates, maintenance costs, property taxes, and insurance.
- Tax Considerations
Rental income from an ADU is taxable. However, homeowners may be eligible for deductions including depreciation, maintenance expenses, property management costs, and insurance. Fannie Mae guidelines also allow ADU rental income to be considered when qualifying for mortgage financing — a detail worth discussing with a lender early in the planning process. A tax advisor familiar with rental property in Arizona can help clarify the specific implications for your situation.
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When a Full ADU Isn't the Goal
Not every homeowner exploring ADU options needs a full residential unit. Some properties face lot coverage limits, HOA restrictions, or utility constraints that make a permitted dwelling impractical. Others simply need dedicated workspace rather than additional housing.
For homeowners whose primary objective is a home office shed, studio, or quiet retreat space separate from the main house, prefabricated backyard structures offer a narrower-scope alternative. The Autonomous WorkPod lineup falls into this category. These are insulated, climate-controlled enclosures with finished interiors, built-in electrical, and a compact footprint designed for residential lots.
Because these backyard she sheds do not include kitchens, bathrooms, or sleeping quarters, they are generally classified as accessory structures rather than dwelling units under most Arizona municipal codes. This distinction can simplify the permitting path — in many jurisdictions, accessory structures that remain below certain size thresholds and do not contain plumbing face lighter review requirements than a habitable ADU. However, local rules vary, and homeowners should confirm permit requirements with their city or county before purchasing.
For those who need functional separation from the main house without the cost, timeline, or regulatory complexity of a permitted dwelling unit, it is a simpler path to the same underlying problem: usable, dedicated space on your own lot.
WorkPod
97 reviews| Overall size | 8.5’W x 12’L x 11’H |
| Floorspace | 102 square feet |
| Ceiling height | 6.8’ to 9.3’ |
| Weight capacity | 2.9 tons |
| Door & Window dimensions, material (include glass) | Main door: 7.5’W x 6.8'H 3 windows: 1.1’W x 7.9’H Window material: Wooden frame, 5/16” tempered glass, composite wood cover Door material: Anodized aluminum frame, 5/16” tempered glass |
| Siding, roof, floor & balcony material | Siding: Plywood 1/2”, wooden frame, honeycomb paper, plywood 3/8”, bitume, housewrap, vinyl siding Roof: Roof shingles Floor: Plywood Balcony: Composite wood |
| Electrical devices | 1 RCB (Residual current breaker) 3 Wall outlet (Universal wall sockets) 1 Ceiling light switch 1 Ceiling light 1 Ventilator switch 1 Ventilator 66ft power cable with 2 connectors |
| Power input | Maximum voltage: 110V AC (US standard) Maximum current: 25A Maximum power dissipation: 2750W |
| Interior furniture | Unfurnished option: 1 Bookshelf, 1 Electrical Cabinet Furnished option: 1 Autonomous Desk, 1 ErgoChair Ultra, 1 Monitor Arm, 1 Cable Tray, 1 Filing Cabinet, 1 Anti-Fatigue Mat, 1 Bookshelf, 1 Electrical Cabinet |
| Compatible with | Portable air conditioner: A/C units with dimensions smaller than 22” L x 20” W x 88” H and a 5.9” vent hole diameter will fit well. Heater: A small personal heater is more than sufficient. |
"I did a lot of research before contacting the sales team. The representative was incredibly helpful, which led me to decide to make the purchase. The process from order to delivery was extremely fast. The assembly was also easy, with the WorkPod being completed in just 3 days by their contractors. I love the result and can't wait to move my office in there!" - Rachael T.
"I'm impressed by the WorkPod's design and functionality." - William H.
"The WorkPod's privacy features make it easy to take important calls or have virtual meetings without interruptions."- Ben D.
FAQs
Are ADUs allowed in Arizona?
Yes. Under HB 2720, all Arizona cities with populations over 75,000 must allow at least one attached and one detached ADU on any single-family residential lot. HB 2928 extends similar requirements to counties, with a compliance deadline of January 1, 2026.
What is the new law for ADU in Arizona?
House Bill 2720, signed in May 2024, is the primary ADU law in Arizona. It requires qualifying cities to permit ADUs as a matter of right and prohibits local restrictions on parking, design matching, and setbacks beyond five feet. HB 2928, signed in May 2025, extends these rules to counties statewide.
How much does an ADU cost in Arizona?
Most ADU projects in Arizona range from $120,000 for a garage conversion to over $400,000 for a custom detached build. In the Phoenix metro area, new construction typically runs $300–$700 per square foot depending on finish level, with additional costs for permitting, utility connections, and site preparation.
Can I put a tiny home in my backyard in Arizona?
It depends on how the structure is classified. A tiny home placed on a permanent foundation that meets local building codes may qualify as an ADU in Arizona under current law. However, tiny homes on wheels are generally not treated as ADUs and may face separate zoning restrictions depending on your municipality.
Can I convert my garage into an ADU in Arizona?
Yes. Garage conversions are one of the most cost-effective ADU types in Arizona, typically ranging from $120,000–$160,000. The converted space must meet building code requirements for habitation, including proper egress, ventilation, and utility connections, and will require a standard building permit.
How long does it take to build an ADU in Arizona?
From initial design through certificate of occupancy, most ADU projects in Arizona take six to eighteen months. Permitting and plan review alone can take several months in cities with heavier workloads. Garage conversions and pre-approved plan projects tend to move faster than custom detached builds.
Does building an ADU in Arizona increase property taxes?
Yes. Adding an ADU increases the assessed value of your property, which will be reflected in your tax bill. However, the increase is based on the value the ADU adds — not a reassessment of your entire property. For most homeowners, the additional rental income or equity gain outweighs the tax increase.
How do I finance an ADU in Arizona?
Common financing options include home equity lines of credit (HELOCs), cash-out refinancing, and construction loans. Site-built ADUs generally qualify for a broader range of conventional loan products. Prefab or manufactured units may face financing limitations, as some lenders do not classify them as real property.
Conclusion
Arizona's 2024–2025 legislation created one of the more straightforward legal frameworks for accessory dwelling units in the country. The opportunity is real — but so are the details. City-level rules, HOA restrictions, lot-specific constraints, and cost variables all shape whether a project is feasible and financially sound.
The most reliable path forward starts with your local planning department. Confirm what applies to your parcel before committing to design, budgeting, or contractor selection. If your priority is speed and cost control, it’s also worth comparing an ADU build to affordable prefab homes as a parallel option, especially for predictable pricing and faster timelines.
For homeowners who do the groundwork early, building an ADU in Arizona can be a practical addition to their property — whether the goal is rental income, family housing, or long-term value.
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