What law passed?
In 2024, Arizona passed groundbreaking legislation. It made Accessory Dwelling Units (ADUs) legal in most single-family neighborhoods. These units are also known as casitas, guest houses, or in-law units. The new laws, HB 2720 and SB 1415, aim to give homeowners more flexibility. They also support multigenerational living. Furthermore, they help tackle the state’s growing housing demand.
But while the law is now in effect, how it’s being implemented varies by city and county. This guide breaks it all down.
What does the law say?
How does it applies to your property?
What to do next if you’re ready to explore building an ADU?
What is an ADU?
An Accessory Dwelling Unit (ADU) is a smaller, independent home located on the same lot as a primary residence. They can be detached backyard homes, garage conversions, additions, or even basement apartments.
ADUs offer flexible living options for aging parents, adult children, guests, or renters. There’s no need to buy or build a whole new home. In Arizona’s climate and neighborhoods, ADUs can be thoughtfully designed to add value, privacy, and functionality.
Understanding Arizona’s New ADU Law
ADUs (Guest house, Casita, Mother-in-law Suite, etc) are becoming legal and more accessible across the state. These laws require jurisdictions with populations over 75,000 to allow at least one ADU on single-family residential lots.
The goal? More housing options, greater flexibility for homeowners, and smarter use of existing neighborhoods.
While cities can still apply certain design standards—like setbacks, height limits, and parking—they can no longer prohibit ADUs outright. The law took full effect in January 2025, but many cities are already making changes.
Cities and Counties can still regulate things like…
- Setbacks and lot coverage
- ADU height
- Parking requirements
- Minimum and maximum size
- Owner occupancy (in some cases)
Is My Jurisdiction Complying with the New ADU Law?
Arizona’s new ADU laws require municipalities and counties with populations over 75,000 to permit at least one ADU on single-family residential lots. However, implementation varies across jurisdictions. Some have fully embraced the changes, while others are still in the process of updating their regulations. Below is a snapshot of how different jurisdictions are responding to the new ADU requirements.
| Jurisdiction | Compliance Status | Notes |
|---|---|---|
| Phoenix | ✅ Compliant | Ordinances updated; ADUs allowed in most single-family zones. |
| Tucson | ✅ Compliant | Fully aligned; ADUs permitted with site and design guidelines. |
| Mesa | ⚠️ In Progress | Draft ordinance under review. |
| Scottsdale | ⚠️ In Progress | Planning commission evaluating ADU policies. |
| Gilbert | ⚠️ Partial Alignment | Some ADU types allowed; updates pending to meet full compliance. |
| Chandler | ✅ Compliant | Recently adopted new ADU regulations. |
| Queen Creek | ⚠️ In Progress | Reviewing ADU ordinance updates; public sessions ongoing. |
| Apache Junction | ❌ Not Yet Updated | No ordinance updates published as of April 2025. |
| Pinal County | ❌ Not Yet Updated | Ordinance revisions not yet released. |
| Maricopa County | ✅ Mostly Compliant | Allows ADUs in unincorporated areas; some design restrictions remain. |
At PlanHAUS, we stay on top of the latest changes—so you don’t have to. Whether you’re in Phoenix, Mesa, Pinal County, or somewhere in between, we can help you determine what’s possible on your property and guide you through the process from start to finish.
