Everything homeowners need to know about building an accessory dwelling unit in Tucson - size limits, setbacks, permits, and the statewide law that forced the city to open ADUs up to nearly every residential lot in 2024.
Last verified: September 2026
9/10 · Very ADU-friendly
1,000 sq ft*
Max ADU size
Matches house*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes the accessory dwelling unit standards in Tucson's Unified Development Code, updated to comply with Arizona House Bill 2720 (2024), for general reference - it is not legal advice. Regulations change; always confirm current requirements with Tucson Planning & Development Services (PDSD) before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new build or garage/casita conversion)
75% of the primary dwelling's gross floor area, or 1,000 sq ft, whichever is smaller
Same height limit that applies to a single-family home in that zone
Every lot is guaranteed at least 650 sq ft of buildable ADU area regardless of how small the primary home is
Common approach when building onto or converting space within the existing home's footprint
Allowed zoning districts
Any zone where a single-family home is permitted, citywide. Arizona House Bill 2720 (2024) required every Arizona city with more than 75,000 residents, including Tucson, to allow ADUs by right on those lots. Tucson's Mayor and Council adopted the updated Unified Development Code standards on October 22, 2024, effective November 21, 2024. Confirm your parcel's zoning with PDSD.
Additional standards
Setbacks, parking & other rules
Setbacks
5 ft from side and rear property lines - the maximum a city may require under state law; front setback follows the zone's standard requirement
Parking
None required. State law bars Tucson from requiring off-street parking for an ADU, or a fee in lieu of parking
Units per lot
At least 1 attached and 1 detached ADU allowed by right per lot; lots of 1 acre or more can add a third detached unit if it's deed-restricted as affordable housing
Owner-occupancy
Not required. State law bars the city from requiring any familial, marital, employment, or other relationship between the occupants of the house and the ADU
Building code
Must meet Tucson's adopted residential building code; newly constructed ADUs are required to have a cool roof
Rental license
Tucson does not require a separate city rental license for standard long-term rentals. Landlords do need an Arizona Department of Revenue transaction privilege tax (TPT) license to report rental income
Ordinance history
How Tucson's ADU rules got here
2021Tucson's first citywide casita ordinance. Mayor and Council adopted a local code amendment (initially adopted October 19, 2021, with a reconsideration hearing that December) allowing accessory dwelling units, or "casitas," on residential lots citywide.
2024Arizona House Bill 2720 signed into law. Signed May 21, 2024, the bill requires every Arizona city with more than 75,000 residents to allow at least one attached and one detached ADU by right on residential lots, caps setbacks at 5 ft, bars parking mandates, and bars owner-occupancy requirements - with a compliance deadline of January 1, 2025.
2024Tucson updates its casita code. Mayor and Council adopted revised Unified Development Code standards on October 22, 2024, implementing HB 2720's size, height, setback, and parking changes; the update took effect November 21, 2024, ahead of the state deadline.
Worth knowing: Tucson's rules are now largely set by the state rather than the city. As long as a project fits the state-mandated formula, standard review is administrative, with no rezoning or public hearing required.
Permit process
How Tucson ADU permitting works
1
Confirm zoning eligibility
Check your parcel's zoning and lot area on the Casitas in Tucson resource page or with PDSD before you design.
2
Prepare your plan set
You'll need a site plan, floor plans and elevations for the ADU, and a floor plan of the existing house to verify the 75%-of-house size calculation.
3
Submit a building permit application
Because ADUs are allowed by right, Tucson reviews them through the standard residential building permit process - no separate zoning hearing or rezoning is required.
4
Plan review
PDSD reviews the plan set for zoning and building code compliance, including the cool-roof requirement on new construction.
5
Construction & inspections
Once your permit is issued, build and schedule the standard framing, plumbing, electrical, and final inspections.
6
Certificate of occupancy
Pass final inspection and obtain sign-off before renting or occupying the ADU.
Timelines and fees vary with PDSD's workload and construction valuation. Confirm current review times and fee schedules directly with PDSD before budgeting.
Budgeting
What it costs to build an ADU in Tucson
Garage/casita conversion
Roughly $65,000-$170,000, the least expensive path since the shell already exists
New detached ADU
Roughly $140,000-$280,000 for a code-compliant, freestanding casita, depending on finishes and size
Building permit fees
Based on construction valuation; confirm the current fee schedule with PDSD
Arizona TPT rental license
Required from the Arizona Department of Revenue if you plan to rent the ADU out; not a Tucson-specific fee
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, finishes, and utility hookups. Tucson's more moderate construction costs and warm climate (no need to over-insulate against deep freezes) generally keep new-build ADUs toward the lower end of the national range.
Before you apply
Tips for a smooth approval
Run the 75%/1,000 sq ft math against your actual house first. The cap only reaches the full 1,000 sq ft if your primary home is large enough - many smaller homes will land closer to the 650 sq ft guaranteed minimum.
Confirm your zoning district before you design. A quick check with PDSD or the Casitas in Tucson resource page avoids redesigning a project that doesn't fit your lot.
Budget for the cool-roof requirement on new construction. It's a real added cost on new detached casitas, so get it into your contractor's bid early.
On a 1+ acre lot, weigh the deed-restricted third unit. Trading a rent restriction for an extra detached ADU can pencil out well depending on your goals.
Don't assume "by-right" means instant. Plan review still takes time - confirm PDSD's current timeline before committing to a move-in date.
FAQ
Common questions
Do I need to live on the property to build an ADU in Tucson?
No. Arizona state law bars cities from requiring owner-occupancy or any other relationship between the occupants of the main house and the ADU, so you can build and rent out an ADU without living on site.
How many ADUs can I build on one lot?
At least one attached and one detached ADU are allowed by right on any qualifying residential lot. Lots of 1 acre or more can add a third detached unit if it's deed-restricted as affordable housing.
Do I need extra parking for an ADU?
No. Arizona law bars Tucson from requiring additional off-street parking for an ADU, or a fee in lieu of parking.
How long does the permit process take?
ADUs go through Tucson's standard by-right residential building permit process, with no rezoning or public hearing required. Actual review time depends on PDSD's current workload - confirm timelines directly with the department.
What's the maximum size for an ADU in Tucson?
75% of your primary home's gross floor area, or 1,000 sq ft, whichever is smaller. Every lot is guaranteed at least 650 sq ft of buildable ADU area regardless of how small the main house is.
How tall can a Tucson ADU be?
The same height limit that applies to a single-family home in your zone. State law bars the city from imposing a stricter height limit on ADUs than it applies to primary homes.
What are the setback requirements?
5 ft from the side and rear property lines - the maximum Tucson is allowed to require under state law. Front setbacks follow the zone's standard requirement for the underlying district.
How much does an ADU cost to build in Tucson?
Garage or casita conversions tend to run roughly $65,000-$170,000, and new detached units roughly $140,000-$280,000, based on local contractor estimates and regional reporting - not counting permit fees.
Why did Tucson's ADU rules change so much in 2024?
Arizona House Bill 2720, signed into law May 21, 2024, required every Arizona city with more than 75,000 residents to allow ADUs by right, capped setbacks at 5 ft, and barred parking and owner-occupancy mandates. Tucson adopted matching Unified Development Code changes that October, effective November 21, 2024.
