Arizona has become one of the most ADU-friendly states in the country — and that shift happened fast. If you have been thinking about adding a casita, a detached rental unit, or an in-law suite to your Phoenix-metro property, the regulatory environment has changed significantly in your favor. This guide covers everything you need to know to go from idea to permit in 2025.
The Big Change: Arizona Senate Bill 1168
In 2022, Arizona passed Senate Bill 1168, which fundamentally changed the ADU landscape statewide. The key provisions that matter to homeowners:
- Cities and towns cannot prohibit ADUs outright on single-family lots. If you own a home on a residential lot, you have the right to build an ADU.
- Owner-occupancy requirements are banned. Arizona cities cannot require you to live on the property to build or rent an ADU. You can build a casita on a rental property you do not occupy.
- Minimum lot size requirements are capped. Cities cannot require a lot larger than the minimum required for a single-family home in that zone as a condition of ADU approval.
- Parking requirements are limited. Cities cannot require more than one additional off-street parking space per ADU.
The practical effect: in almost every Phoenix-metro city, if you have a single-family lot and meet setback requirements, you can build an ADU. The question is no longer "can I?" — it is "what exactly can I build, and how do I get it permitted?"
ADU Types Allowed in Arizona
Arizona law recognizes and allows all standard ADU types on residential lots:
- Detached ADU (Casita): A fully separate structure in the backyard. The most popular option for rental income or guest use.
- Attached ADU: Built onto the existing home — typically an addition with its own entrance, kitchen, and bath.
- Garage Conversion: Converting an attached or detached garage into livable ADU space.
- Junior ADU (JADU): Up to 500 sqft created within the existing footprint of the primary home — often a converted bedroom with a kitchenette. Lower cost, faster permits.
Setback and Size Requirements by City (2025)
While SB 1168 sets the floor, each city retains the right to set setbacks, height limits, and size caps within certain parameters. Here is how the major Phoenix-metro cities currently stand:
| City | Max ADU Size | Rear Setback | Side Setback | Max Height |
|---|---|---|---|---|
| Scottsdale | 1,200 sqft or 50% of primary home | 10 ft | 5 ft | 18 ft |
| Phoenix | 1,000 sqft (detached) | 5 ft | 5 ft | 24 ft |
| Tempe | 1,200 sqft | 5 ft | 5 ft | 20 ft |
| Gilbert | 1,200 sqft | 10 ft | 5 ft | 18 ft |
| Chandler | 1,000 sqft | 10 ft | 5 ft | 18 ft |
| Mesa | 1,200 sqft | 5 ft | 5 ft | 20 ft |
| Paradise Valley | 800 sqft or 25% of primary home | 20 ft | 10 ft | 14 ft |
| Peoria | 1,200 sqft | 10 ft | 5 ft | 20 ft |
Note: Requirements change periodically. Always verify current code with the relevant city development services department or consult with a licensed contractor before finalizing your plans.
The ADU Permit Process in Phoenix Metro
Most Phoenix-area cities process ADU permits through their standard residential building permit pathway. Here is what a typical timeline looks like:
- Week 1–2: Site feasibility check — confirm setbacks, lot coverage, and utility availability. This is typically a conversation with city planning staff (free) or done by your contractor.
- Weeks 2–6: Architectural drawings prepared. For most ADUs under 1,000 sqft, a simple plan set from a designer or drafter works. Larger or more complex ADUs may require a licensed architect.
- Weeks 4–10: Permit application submitted and under review. Phoenix, Tempe, and Mesa have moved to expedited review programs for ADUs — permit approval in some cases in as little as 3–4 weeks.
- Permit Approval: Once approved, construction can begin. Most detached ADUs complete in 12–18 weeks from permit approval.
What Does an ADU Actually Cost in Phoenix?
All-in costs for Phoenix-metro ADUs in 2025, based on recent completed projects:
| ADU Type & Size | Cost Range | Notes |
|---|---|---|
| Studio Casita (350–450 sqft) | $75,000 – $120,000 | Kitchenette, 1 bath, mini-split HVAC |
| 1BR Casita (500–700 sqft) | $110,000 – $175,000 | Full kitchen, 1 bath, separate electrical |
| 2BR Casita (750–1,000 sqft) | $155,000 – $250,000 | Full kitchen, 2 bath, laundry connections |
| Garage Conversion (450–650 sqft) | $45,000 – $95,000 | Lower cost — structure exists |
| Junior ADU (300–500 sqft) | $30,000 – $65,000 | Within existing footprint |
Financing Your ADU
Several financing options are available for ADU construction in Arizona:
- Home equity loan or HELOC: The most common option for homeowners with equity. Rates and terms vary. You borrow against your existing equity and repay over time.
- Cash-out refinance: If your rate is competitive, refinancing to pull out equity for construction can make sense. Less attractive in the current rate environment for many homeowners.
- Construction loan: A short-term loan that funds construction in draws. Converts to a permanent mortgage on completion. More complex but useful if you have limited equity.
- Renovation or rehab loan (FHA 203k, Fannie Mae HomeStyle): Government-backed products that allow you to finance both the purchase or refinance and the ADU construction in one loan.
Many homeowners find that the rental income from their ADU covers the financing cost entirely, making the project essentially self-funding over time.
HOA Restrictions: The One Big Wildcard
Arizona SB 1168 governs city and town ordinances — but it does not override private HOA covenants, conditions, and restrictions (CC&Rs). If your property is in an HOA, your CC&Rs may prohibit or restrict ADUs regardless of what state law allows.
Before designing anything, pull your HOA's CC&Rs and check specifically for language about: secondary structures, accessory buildings, rental restrictions, and occupancy limits. Some HOAs prohibit short-term rentals but allow long-term rental of ADUs. Others prohibit any additional dwelling units. Know your CC&Rs before you spend money on plans.
Bottom Line: Is an ADU Right for You?
For most Phoenix-metro homeowners with a standard single-family lot, the regulatory environment has never been better for ADU construction. The question is whether the economics work for your specific situation.
A 600 sqft casita in Tempe or Mesa, renting at $1,350–$1,550/month, generates $16,200–$18,600/year in gross rental income. At a construction cost of $130,000, that is an 8–10 year payback — plus a permanent increase in your property value and equity.
If you want a straight-line assessment of whether an ADU makes sense on your specific property — setbacks, lot coverage, city requirements, and a real cost number — that conversation is free.