How many ADUs/casitas can I build on my lot in Tucson?

Two accessory dwelling units (casitas) are permitted per parcel developed with a single-family Family Dwelling (one per parcel with a duplex); a third is allowed on lots over one acre if at least one ADU is deed-restricted as affordable housing. Both attached and detached units must comply with Accessory Dwelling Unit zoning standards (UDC Section 6.6.3.B) — size capped at 75% of the principal dwelling's floor area (max 1,000 sq ft) or up to 650 sq ft regardless of the principal dwelling's size, a 5-foot side/rear setback, and the primary dwelling's zone height limit (commonly 25 feet). The permit bundles zoning, building, and utility review. Source: Tucson Unified Development Code Section 6.6.3 and City of Tucson PDSD Residential Permits page.

Accessory Dwelling Unit (Casita) Permit in Tucson, Arizona

Verified

Accessory Dwelling Units (ADUs), locally called 'casitas,' are allowed by right in Tucson, one per residential lot. The permit includes zoning, building, and utility review and must meet applicable Accessory Dwelling Unit standards for both attached and detached units. Falls under the Fast Lane (10-business-day) review track.

Verified 2026-07-03 · Source

From$89.45Building Permit Fee (valuation-based, same Construction Valuation Table as new construction) — see all 2 fees below

When you need this permit

A permit is required for any ADU/casita — defined, like any dwelling unit, as having a place to sleep, a bathroom, and a kitchen
Two accessory dwelling units are permitted per parcel developed with a Family Dwelling (single-family home); a parcel developed with a duplex is permitted one accessory dwelling unit. A third ADU is allowed on a lot/parcel over one acre if at least one of the ADUs on that lot is a deed-restricted affordable unit (80% of area median income or less)
Size: an ADU/casita is limited to 75% of the principal dwelling's gross floor area, not to exceed 1,000 sq ft of gross floor area OR up to 650 sq ft of gross floor area regardless of the principal dwelling's size, whichever is more permissive
Height: except as otherwise specified, an ADU/casita follows the dimensional standards of the principal (single-family) land use in the same zone — commonly a 25-foot height limit — rather than the lower 12-foot cap that applies to other accessory structures (accessory dwelling units are explicitly excepted from that 12-foot cap)
Setback: minimum side and rear yard setback for an ADU/casita is 5 feet
A cool roof (high albedo level >60 SRI, or other cool roof technology per the ICC Green Construction Code) is required if the ADU/casita is built as a new structure
No vehicular parking is required to be provided for ADUs/casitas
ADUs are not required to match the exterior design, roof pitch, or finishing materials of the primary single-family dwelling on the same lot
ADUs/casitas are not subject to maximum residential density standards, and are exempt from being classified as a multifamily development or requiring a commercial site plan/commercial development standards when added to an established, occupied family dwelling
Both attached and detached ADUs must follow these Accessory Dwelling Unit standards (Tucson Unified Development Code (UDC) Section 6.6.3.B, as amended through Ordinance 12219, 12/16/2025)
Permit includes zoning, building, and utility review as a bundled 'New Building/Dwelling, Development Package, Accessory Dwelling Unit' permit type
A dedicated Accessory Dwelling Unit checklist is published separately from the general New Dwelling and Addition/Alteration checklists
Falls under the Fast Lane (10-business-day performance goal) as 'Residential ADU / Casita'

Required documents

Required
Residential Building Permit Application Checklist - Accessory Dwelling Unit
City of Tucson PDSD checklist specific to ADU/casita submittals, separate from the New Dwelling and Addition/Alteration checklists
Required
Construction Drawings
Site plan and floor/framing plans showing the ADU's compliance with size, height, and setback standards

Fee schedule

Fee type	Amount	Notes
Building Permit Fee (valuation-based, same Construction Valuation Table as new construction)	$89.45 minimum ($1-$2,000 valuation), scaling per the Building Permit Fees for New Construction table	City of Tucson FY27 Fee Schedule (Section 4-02.4); ADUs are billed as new dwelling construction, not under a separate ADU-specific fee line
Digital Filing Fee	1% of the total fee, minimum $18.54	City of Tucson FY27 Fee Schedule (Section 4-01.5.1)

Review timeline

10–10 business days

Tucson’s published plan-review target

Inspection process

1
Foundation/Footing
Before concrete pour
2
Framing
Structural framing and connections for attached or detached units
3
Final
All work complete per approved plans and ADU zoning standards

Tips

ADU/Casita permits are reviewed in the Fast Lane (10-business-day goal) — faster than the Standard Lane (20-business-day) used for a full new primary dwelling.
Up to two casitas are allowed on a lot with a single-family Family Dwelling (one with a duplex, a third on lots over 1 acre if one unit is deed-restricted affordable); verify lot eligibility and applicable size/height zoning limits before designing.
An ADU/casita can be sized either as 75% of the primary home's floor area (capped at 1,000 sq ft) OR up to 650 sq ft outright regardless of the primary home's size — whichever route allows the larger unit.
The 5-foot side/rear setback and the 'match the primary dwelling's zone height limit (commonly 25 ft)' rule are more permissive than the 12-foot cap and standard perimeter-yard setback that apply to other (non-ADU) accessory structures — the UDC explicitly exempts ADUs from those tighter general accessory-structure limits.
A cool/high-albedo roof (>60 SRI or equivalent per the ICC Green Construction Code) is mandatory for any newly built casita structure, and no off-street parking needs to be provided for it.
The City's Casita Model Plan Library and 'Casitas in Tucson' regulations page (casitas-in-tucson-cotgis.hub.arcgis.com) are hosted on a JavaScript-rendered ArcGIS Hub site; the specific numeric standards were successfully retrieved by rendering the page (Playwright) and are independently corroborated by the governing Tucson Unified Development Code (UDC) Section 6.6.3, Residential Uses, hosted by American Legal Publishing — the UDC is the controlling legal text and was used as the primary source for the standards above.

Frequently asked questions

How many ADUs/casitas can I build on my lot in Tucson?: Two accessory dwelling units (casitas) are permitted per parcel developed with a single-family Family Dwelling (one per parcel with a duplex); a third is allowed on lots over one acre if at least one ADU is deed-restricted as affordable housing. Both attached and detached units must comply with Accessory Dwelling Unit zoning standards (UDC Section 6.6.3.B) — size capped at 75% of the principal dwelling's floor area (max 1,000 sq ft) or up to 650 sq ft regardless of the principal dwelling's size, a 5-foot side/rear setback, and the primary dwelling's zone height limit (commonly 25 feet). The permit bundles zoning, building, and utility review. Source: Tucson Unified Development Code Section 6.6.3 and City of Tucson PDSD Residential Permits page.

Sources & verification

Verified against official sources. Last reviewed 2026-07-03.

Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Tucson building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.

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