As of October 2026, a 2026 Arizona cost guide prices a 600 sq ft detached casita in Tucson at about $90,000 basic, $155,000 mid-range and $250,000 high-end, with permits estimated at $2,500 to $4,000. Caliche removal and desert-rated cooling are not in those figures. Your lot, size and finishes decide where you land.
What do the published Tucson figures look like?
- Basic 600 sq ft casita: about $90,000.
- Mid-range: about $155,000.
- High-end: about $250,000.
- Permits: an estimated $2,500 to $4,000.
- Basic garage conversion: from about $90,000.
All from one 2026 Arizona cost guide. For a reality check, a small 2023 survey of Tucson casita applicants found that most of the 10 who reported costs expected $140,000 to $200,000. Neither figure is our price; we quote in writing after a site visit.
What sits outside those numbers?
- Caliche. $5,000 to $20,000 to remove on lots that have it, per the same guide.
- Cooling. $6,000 to $14,000 for heat-rated HVAC.
- Impact fees. About $2,750 to $4,310 in 2023, depending on size.
- Utility work. Sewer, water and power runs to the casita, and any panel upgrade.
- Septic. On unsewered lots outside the city, a system sized for the added unit.
- Plans. A purchased model plan, or a custom design.
Can a model plan save money?
It can trim design cost and review time. Tucson's Casita Model Plan Library holds pre-approved designs bought directly from their designers. You still pay for the site plan, utilities, fees and construction, and a model plan has to suit your lot.
How should I compare bids?
Line by line. Ask each builder to put these in writing:
- design, engineering and fees: included or not
- utility scope, and where on the lot it ends
- cooling equipment type and size
- caliche: allowance or exclusion
- finish allowances, and what happens if you go over
Why does it depend so much?
Because the same 600 sq ft casita can sit 20 feet or 120 feet from the sewer, on soft soil or caliche, with a kitchenette or a full kitchen. Those three choices alone can move the total by tens of thousands of dollars.
Sources, as of October 2026
- CostToBuildHouse.com, "2026 Arizona ADU (Casita) Cost Guide," Tucson figures, permit estimate, caliche and HVAC ranges.
- Arizona Daily Star, 2023 report on Tucson casita applications, impact fees and applicant cost survey.
- City of Tucson PDSD, 2024 Year in Review (Casita Model Plan Library).
Related
Updated October 2026