ADU types · Phoenix, AZ
The ADUs and casitas we design, permit and build around Phoenix.
Four kinds of unit and one team. The right one depends on your lot size, what is already standing on it, and whether you plan to rent it.
How do the types compare in Phoenix?
Based on the City of Phoenix ADU guidance and text amendment Z-TA-2-24, as of October 2026. Your zoning district and lot coverage decide the final numbers.
| Type | Where it goes | Phoenix size cap | Often a fit when |
|---|---|---|---|
| Detached ADU | New building in the yard | Lots up to 10,000 sq ft: 1,000 sq ft. Larger lots: up to 3,000 sq ft or 10% of the lot. Never over 75% of the main home. | The backyard has room and you want privacy |
| Garage conversion | Inside the existing garage | The same caps; the garage footprint usually sets the real limit | The garage is sound and you can park elsewhere on the lot |
| Attached ADU | Joined to the main house | The same caps | Yard space is short but the house can grow |
| Guest house | Usually detached | Set by each city's guest house rules, not the ADU section | The space is only for family and visitors |
Is there a junior ADU option in Arizona?
Not as a separate category. Arizona's ADU statute speaks of attached and detached units and does not create a smaller "junior" class. If you want to turn a bedroom wing into a unit, we ask city zoning staff how it will be classified before design starts.
Which type costs the least?
Usually the one that reuses walls and a roof you already have. A garage conversion or a modest attached unit tends to cost less than a new detached casita, though Phoenix's replacement-parking rule and any electrical upgrade can narrow the gap. See the Phoenix ADU cost guide.
Not sure which type fits?
Tell us what is on your lot today. We tell you which ADU types the zoning allows and which one makes sense for your budget. We work in Phoenix, Scottsdale, Tempe, Glendale and Paradise Valley.