Casitas and ADUs in the Catalina Foothills

Who reviews a casita in the Catalina Foothills?

Pima County Development Services. The Catalina Foothills is an unincorporated community, so neither the City of Tucson nor a town has zoning authority there.

What does the county ADU law require?

HB 2928, signed May 23, 2025, added A.R.S. § 11-810.01. As of October 2026, it requires a county to allow, on any lot where a single-family home is allowed:

• At least one attached and one detached ADU, plus one more detached unit on lots of an acre or more, where the county may require one unit to be restricted-affordable.
• At least 75% of the main home's floor area or 1,000 sq ft, whichever is less; counties may allow more.
• Side and rear setbacks of no more than 5 feet.
• No added parking, and no ban on separate long-term rental of 90 days or more.

If a county had not adopted rules by January 1, 2026, the statute allows ADUs on all residential lots in that county without limits.

Has Pima County adopted its ordinance?

The county prepared a draft ADU ordinance in 2025 to meet the new law, amending Chapters 18.03 and 18.09 of its code. We have not confirmed the final adopted text, so we check it with the county for each project rather than quoting draft numbers.

What usually matters on a Foothills lot?

• Septic. Where a lot is not on sewer, state law lets the county require an adequately sized septic system before an ADU is built.
• Slope and washes. Hillside grading and drainage rules can limit where a casita sits.
• Private covenants. Some Foothills subdivisions have deed restrictions or HOAs; the county law does not override them.
• Guest house option. Pima County's guest house rules remain for family-only use. See guest houses.

Related

As of October 2026, from A.R.S. § 11-810.01 (HB 2928, Laws 2025, Ch. 217), Pima County's draft ADU ordinance (2025) and Pima County's Guest Houses page.