How much does it cost to build a casita in Arizona?
Updated October 9, 2026
Short answer: builders in the Phoenix area quote roughly $150 to $300 per square foot for a new detached casita, all-in. That's about $150,000 to $300,000 for a typical one. Converting a garage or building an attached unit usually costs less.
Rough cost by size
| Casita size | At $150–$300 per sq ft |
|---|---|
| 400 sq ft | $60k – $120k |
| 600 sq ft | $90k – $180k |
| 800 sq ft | $120k – $240k |
| 1,000 sq ft | $150k – $300k |
Small units cost more per square foot, because the kitchen, bathroom, utility hookups and permits cost about the same whatever the size.
What pushes the price up or down
- Attached or detached. Attached units share a wall and are close to existing plumbing and power. Detached units need their own utility runs, which can cost a few thousand dollars to $30,000 or more.
- Kitchen and bathrooms. Each adds real cost; a full kitchen can add $10,000 or more.
- Site work. Caliche soil, slopes and tight access for equipment all add cost.
- Design, engineering and permits. Typically $5,000 to $20,000 combined; city fees vary.
- Finishes. Custom finishes or a second story push past $300 per sq ft.
The cheapest casita is the one that fits
Before you get quotes, find out what your lot actually allows. Arizona law lets most homeowners build up to 75% of their home's living area or 1,000 sq ft, but your zoning district's lot coverage and setbacks often cut that down. A plan that has to be redrawn costs time and design fees.
Type your Mesa or Tempe address. CasitaFlow pulls your parcel and zoning and shows the largest casita allowed, the setbacks, and a drawing of where it fits. Free, no account needed.
Common questions
How much does it cost to build a casita in Arizona?
Most new detached casitas in the Phoenix area run about $150 to $300 per square foot all-in, or roughly $150,000 to $300,000. Garage conversions and attached units usually cost less, often $50,000 to $95,000.
Is a garage conversion cheaper than a new casita?
Usually. The walls, roof and slab already exist and utilities are close by. In Tempe, a garage conversion also adds no lot coverage.
Are prefab casitas cheaper?
The building can be, but site work, the foundation, utility hookups, permits and delivery still apply, so the all-in difference is usually smaller than the price tag suggests.
How long does it take to build a casita?
Plan on roughly six to nine months from first design to move-in, including permits. Construction itself is often two to four months for a simple unit.
These are typical ranges reported by Phoenix-area builders, not quotes. Get bids from licensed contractors (check them at roc.az.gov).