Accessory Dwelling Units Code Amendment

Accessory Dwelling Units Code Amendment Draft Proposal
What could these housing options mean for Tucson?

The City of Tucson Planning and Development Services Department recently held a series of virtual public meetings to share a proposed code change to allow backyard casitas (also known as Accessory Dwelling Units) in Tucson. Attendees heard how this housing option can provide affordable housing, help seniors age in place, and promote sustainable infill development. 

Staff presented a draft proposal for new zoning regulations to permit this housing type. This proposal was developed based on what we heard at public meetings held earlier this year, and input from a stakeholder group representing a range of viewpoints and expertise. Participants had a chance to share feedback and hear from other community members.

Have questions related to ADUs? Check out our ADU Frequently Asked Questions here.

Want to provide additional feedback? If you would like to provide feedback on the proposal presented at the public meetings, please use the following survey.

Watch a recording of one of the meetings here:


Public Meetings to Gather Community Input

The first round of public meetings were held on February 24 and 25 for members of the public to learn more about how Accessory Dwelling Units can provide additional housing options in Tucson, how they are regulated today, and what changes are being considered in order to make this housing option more accessible. Participants also had a chance to share their thoughts and feedback. Additional meetings will be held later in the spring to share a draft proposal that will be developed based on the public input.

Review the presentation that was shared.

Review a meeting summary and participant input.

View meeting video


On Tuesday, November 17, 2020, Mayor and Council directed Planning and Development Services to begin the process of amending the Unified Development code to define and permit Accessory Dwelling Units (aka casitas), identify the zones where they are appropriate and create development standards regulating unit size, height, minimum lot size, maximum lot coverage, setbacks, parking requirements and other relevant aspects​ in order to promote this affordable housing option in a manner that is compatible with existing neighborhoods. This process will involve extensive public outreach and engagement. Follow the process here to learn how to get involved.

View the presentation that was shared with Mayor and Council here.

What is an Accessory Dwelling Unit?

  • An Accessory Dwelling Unit is an independent housing unit with its own kitchen, bathroom, living and sleeping space. These units are typically under 1,000 square feet and are accessory to a primary residence.  

  • ADUs can be detached, attached or interior to the primary residence (i.e. through the conversion of a garage, basement or attic). These units are often referred to as casitas, mother-in-law units or granny flats, among other terms.  

ADU examples

Image courtesy of AARP, The ABCs of ADUs

What are the Benefits?

Accessory Dwelling Units have many benefits. This housing style can be a means to:  

  • Increase the supply of affordable rental housing  
  • Encourage more flexible housing options for seniors  
  • Support multi-generational households and living arrangements  
  • Provide supplemental income to landowners and promote neighborhood stability​  
  • Support climate-resilient infill development in context with existing neighborhoods  

In the past decade, many cities have taken steps to legalize ADUs as a way to add to their affordable housing stock and meet other community goals. Some states have even enacted legislation to make this housing option available statewide, including California, Oregon and New Hampshire. 

Why are ADUs being considered in Tucson?

This proposed code amendment stems from and supports ongoing analysis and policy recommendations related to housing needs and sustainability goals in our community.  

  • The City of Tucson has been working with Pima County on a Housing Study to understand our local housing market and identify gaps in our housing stock. Initial findings show that over half of renter households and over 22% of homeowner households are housing cost burdened, meaning they spend more than 30% of household income on housing costs (i.e. rent, mortgage, property tax, utilities).  ADUs can often be an affordable housing option. As a smaller living space, the cost of renting an ADU can be lower than that of a larger apartment. Additionally, adding to the overall supply of housing across the city tends to promote stable rent levels.  

  • On June 9, 2020, Mayor and Council directed staff to form a Commission on Equitable Housing and Development. This Commission has been tasked with providing advice to the Mayor and Council on topics such as: how the City can increase city investment in housing; how to preserve affordability while increasing housing production/ stock; and how to protect barrios and communities from rapid change and displacement.  

  • On September 9, 2020, Mayor and Council adopted a Climate Emergency Declaration calling for carbon neutrality by 2030 and the development of climate adaptation and mitigation strategies. ADUs can be an important tool to support compatible residential infill development. ADUs represent an efficient use of existing infrastructure by adding new housing in already developed areas. As a smaller footprint housing option, ADUs are typically energy efficient structures. Furthermore, these units are often developed in central neighborhoods with multi-modal transportation options. ADUs are an important means to retrofit our neighborhoods to be more climate-resilient.  

  • The Age Friendly Tucson Action Plan was adopted by Mayor and Council in May 2019. Goals of this plan include providing affordable housing options for older adults and to facilitate older adults and people with disabilities aging in place. ADUs are a way to support  these goals, as they can be an affordable option for seniors, and also support aging in place and aging in proximity to family and caregivers.  

How are ADUs currently regulated in Tucson?

  • “Accessory dwelling unit” is not a defined term in the Unified Development Code (UDC). In fact, the code currently states that accessory structures within residential zones may not be a dwelling unit.  

  • Accessory sleeping quarters/guest house are allowed, provided other regulations are met, however, a full kitchen in the unit is not permitted, as sleeping quarters are not intended to be a self-contained unit.  

  • A second dwelling unit is allowed in certain districts, depending on the lot size and ability to meet other zoning regulations. Minimum lot size requirements and density regulations make it difficult to develop ADUs on most standard size lots in urban residential districts.  

What comes next and how can I get involved?

We will be holding a series of public meetings beginning in early 2021 to share information about this proposal and get input from the public. Watch this page or subscribe to the PDSD newsletter to stay informed!