Building a casita in Tempe, Arizona

How the state ADU law applies in Tempe

Tempe 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 Tempe 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: Tempe cannot require setbacks greater than 5 feet.
• Parking: Tempe cannot require additional off-street parking beyond what the primary home has.
• Owner-occupancy: Tempe cannot require you to live in the main house.
• Materials: Tempe cannot require exterior materials that match the primary dwelling.
• Height / coverage: Tempe cannot impose stricter height or lot-coverage limits on the ADU than on the primary home.

What the state law guarantees you in Tempe

Tempe is well above the 75,000-population threshold, so Arizona's state ADU statute applies. On a single-family lot the city must allow:

• At least one attached ADU and one detached ADU.
• Size up to 1,000 sq ft on lots ≤ 10,000 sq ft, or the lesser of 3,000 sq ft / 10% of net lot area on larger lots — never more than 75% of the main home.
• 5-foot maximum setbacks.
• No extra off-street parking requirement.
• No owner-occupancy requirement at the state-law baseline.

What to confirm with the city

Tempe's specific permit process, submittal checklist, plan-review timeline, impact fees, and — critically — its rules on short-term and long-term rental of an ADU are set locally and change frequently. Before you underwrite an ASU-area rental strategy, confirm current rental rules directly with Tempe's Community Development department. Then pair this with our casita cost guide, our financing options, and the HOA rules page.

What still varies by city

Even though the state sets the baseline, Tempe'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 Tempe and its utility providers. Confirm the details with the Tempe planning department before you sign anything with a builder.

HOAs still matter in Tempe

Big chunks of Tempe 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 Tempe homeowners

• Pull your CC&Rs and confirm your neighborhood permits detached ADUs (or that you have no HOA).
• Call Tempe 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 Tempe

Costs in Tempe 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.