Building a casita in Tucson, Arizona

How the state ADU law applies in Tucson

Tucson has a population well above 75,000, so it's covered by Arizona's new state ADU statute. That means the city is required to allow, on any single-family lot:

• At least one attached accessory dwelling unit (part of your existing home).
• At least one detached accessory dwelling unit — a true backyard casita.
• A third detached ADU on lots of one acre or more, if one unit is deed-restricted affordable.

The baseline Tucson must follow

• Size: up to 1,000 sq ft on lots ≤ 10,000 sq ft; the lesser of 3,000 sq ft or 10% of net lot area on larger lots — and never more than 75% of the main home's gross floor area.
• Setbacks: Tucson cannot require setbacks greater than 5 feet.
• Parking: Tucson cannot require additional off-street parking beyond what the primary home has.
• Owner-occupancy: Tucson cannot require you to live in the main house.
• Materials: Tucson cannot require exterior materials that match the primary dwelling.
• Height / coverage: Tucson cannot impose stricter height or lot-coverage limits on the ADU than on the primary home.

Tucson-specific rules

• Tucson allowed ADUs before the state law via its own code amendment, and has updated its code to align with HB 2720.
• Size: up to 75% of the primary dwelling's gross floor area, with a hard max of 1,000 sq ft — but every lot qualifies for an ADU of at least 650 sq ft regardless of how small the primary house is. Small homes still get a real casita.
• Tucson requires "cool roofs" (reflective roofing) on new ADUs. Factor the material spec into your bids.

Where older Tucson rules may conflict with state law

A few older Tucson provisions — like owner-occupancy requirements — may conflict with the new state statute, which prohibits cities from forcing an owner to live on-site. Rather than assert either way, we tell readers the same thing we'd tell a client: confirm current requirements directly with Tucson Planning & Development Services before you file a permit. The rules are moving.

What a Tucson casita costs

Tucson tends to run a bit lower than the Phoenix metro on per-square-foot builds, but the same $150–$300+ band applies once you factor cool-roof requirements and utility runs. See the full breakdown in our Arizona casita cost guide, then compare loan options in the financing guide.

What still varies by city

Even though the state sets the baseline, Tucson's specific permit process, submittal checklist, plan-review timeline, and impact fees are set locally. Building codes, mechanical requirements, and utility connection rules are also administered by Tucson and its utility providers. Confirm the details with the Tucson planning department before you sign anything with a builder.

HOAs still matter in Tucson

Big chunks of Tucson sit inside HOA-governed neighborhoods. The state ADU law does not override private HOA covenants (CC&Rs). Read yours before you start. Our HOA rules page walks through exactly what to look for.

Practical steps for Tucson homeowners

• Pull your CC&Rs and confirm your neighborhood permits detached ADUs (or that you have no HOA).
• Call Tucson planning and ask for their current ADU submittal checklist under the new state statute.
• Get a survey. Setbacks are 5 feet minimum — no guessing.
• Line up financing before you commission plans. See our financing guide.
• Get at least two contractor bids with itemized scope.

What a casita costs in Tucson

Costs in Tucson track the metro Phoenix baseline: roughly $150 to $300+ per square foot, with most detached builds landing between $150,000 and $300,000 all-in. Utility runs, site conditions, HOA design requirements, and contractor overhead drive most of the variance. Read the full Arizona casita cost guide.