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Arizona has addressed its housing shortage by legalizing and regulating Accessory Dwelling Units (ADUs), often called casitas or guest houses. These self-contained living spaces—either attached to or separate from a primary residence—offer homeowners a practical solution for multi-generational living, rental income, or increased housing availability.
With the passage of House Bill 2720, the state has mandated that many municipalities allow ADUs in single-family residential zones. If you’re considering adding one to your property, understanding the new regulations and local policies is crucial.
Statewide ADU Legislation: What You Need to Know
On May 21, 2024, Governor Katie Hobbs signed House Bill 2720, providing statewide uniformity regarding ADUs across Arizona. House Bill 2720 mandates that municipalities with populations over 75,000 must allow at least one attached and one detached ADU per lot in single-family residential zones. Additionally, for lots or parcels that are one acre or larger, municipalities must permit at least one additional detached ADU if at least one of the ADUs is designated as a restricted-affordable dwelling unit.
Here’s what the law outlines:
- Homeowners can build one attached, detached, or internal ADU per lot.
- Size limits may vary by municipality. Homeowners should confirm ADU size allowances with their local planning department.
- Municipalities must allow ADUs if they fall within the state law, but they can impose certain design and location regulations.
This statewide policy makes it easier for homeowners to expand their living spaces, whether for family use or rental purposes. But what about local city regulations? Let’s take a look.
How Arizona Cities Are Adapting
With the new law in place, municipalities like Phoenix and Tucson have quickly updated their zoning codes to reflect state requirements.
Phoenix ADU Rules
Consistent with the new law, Phoenix permits up to two ADUs per lot in single-family residential zones (one attached and one detached). A third ADU is allowed on lots measuring at least one acre, provided that at least one of the ADUs qualifies as affordable housing. Here’s what to keep in mind:
- Each ADU shall not exceed 75% of the main house’s gross floor area, and for lots up to 10,000 square feet in net area, 1,000 square feet; for lots over 10,000 square feet in net area, the lesser of 3,000 square feet or ten percent of the net lot area.
- The maximum size depends on the lot size and zoning restrictions.
- Off-street parking requirements may apply, depending on the location.
Tucson’s ADU Updates
Tucson permits at least one ADU per lot. The maximum size is 75% of the gross floor area of the primary dwelling, up to a maximum of 1,000 square feet. All lots qualify for an ADU of at least 650 square feet, however, regardless of dwelling size. Additional considerations may apply based on historic or designated overlay zones.
For homeowners in other Arizona cities, it’s best to check with local planning departments to ensure compliance with specific municipal requirements.
Key Considerations for Homeowners
While the new law makes ADU construction more accessible, there are still important factors to consider before breaking ground.
HOA Rules & Restrictions
While state law mandates that municipalities allow ADUs, it does not override private covenants or restrictions set by HOAs. Therefore, even if local zoning permits an ADU, your HOA may have rules that restrict or prohibit their construction.
Zoning & Lot Coverage
Not all properties are automatically eligible for ADUs.
- Confirm your zoning classification using tools like Phoenix’s “My Community Map” to ensure compliance.
- Check your lot coverage limits—some zoning districts restrict how much of the land can be covered by structures, including ADUs.
Rental & Occupancy Considerations
Arizona’s ADU law provides flexibility for homeowners looking to rent out their units. However, local ordinances may still impose short-term rental restrictions or require owner occupancy on the property – owners should confirm any potential restrictions.
Permits & Building Codes
Before constructing an ADU, homeowners must obtain the necessary permits and comply with local building codes. Municipalities may have specific requirements related to:
- Structural safety (foundation, roofing, etc.).
- Utility connections (plumbing, electricity, sewage).
- Fire and emergency access (fire sprinklers, exit pathways).
- Setback and height restrictions (distance from property lines, max height limits).
Failure to obtain proper permits can lead to fines, legal issues, or even forced removal of the ADU. Homeowners should consult with qualified legal counsel, zoning officials, and contractors before proceeding with construction.
Why ADUs Matter for Arizona’s Housing Market
The legalization of ADUs is more than just a win for homeowners—it’s a game changer for Arizona’s housing market. With rising housing costs and increasing demand for affordable living spaces, ADUs offer a practical and cost-effective solution.
Whether you’re looking to accommodate aging parents, generate rental income, or simply increase your property’s value, ADUs provide an accessible housing option without the need for large-scale developments.
Ready to Build an ADU? Here’s Your Next Step
If you’re thinking about building an ADU on your property, Gottlieb Law can help you navigate the legal and zoning complexities. From ensuring compliance with state and local regulations to addressing HOA restrictions and rental agreements, our team provides the legal guidance you need to move forward confidently.
Contact Gottlieb Law to discuss your ADU plans and ensure you’re fully prepared to take advantage of Arizona’s new housing opportunities.