What is an "ADU"?
Accessory dwelling units, or ADUs, are self-contained, smaller living spaces that are an extension of an existing property. They are often called mother-in-law suites, granny flats, casitas, backyard cottages, garage apartments or basement apartments. An ADU has its own kitchen, bath and sleeping area, but is not considered a separate property that could be sold on its own.
Learn more about these living spaces
What might change in how Denver regulates ADUs?
Beginning fall 2021, city planners will look at how the Denver Zoning Code regulates ADUs. This project will not change where in the city ADUs are allowed, but will look at how they are designed, how they fit in with different types of neighborhoods and block patterns, and how updates to the zoning code may reduce barriers to creating ADUs.
Participate in this project
See if your property is zoned to allow an ADU
Community Advisory Committee
One way to participate in this project is on a community advisory committee, which is a group of 15 to 20 community members who:
- represent a diverse set of community interests,
- meet regularly throughout the process to help guide the project and work with city planners,
- help spread awareness about the project and gather public input, and
- seek consensus and to balance multiple viewpoints on project recommendations.
The community advisory committee will likely meet for two hours every other month. This work is expected to last for about one year.
Committee members are expected to engage in respectful and constructive discussions and commit to a fair process and civil discourse. Committee members should be willing to balance viewpoints to reach general agreement. The committee will likely meet virtually using Zoom.
Note: A public health order currently in effect requires volunteer committee members who perform in-person activities on city property or at other places in the community to show proof of vaccination for the COVID-19 virus. Visit DenverGov.org/covid19 for additional information.
Apply to join the Community Advisory Committee
View committee selection criteria(PDF, 101KB)
Spread the Word
Invite others to participate in the zoning code update for ADUs.
Arrange a meeting or workshop for your community group
If you are part of a neighborhood or interest group and would like city staff to attend a meeting or an event, please let us know! We are happy to set up presentations, Q&A sessions, or just listening sessions where we can hear from your members directly, either virtually or in person.
As public workshops, small groups, and surveys are available, they will be posted here. Sign up to receive email updates as activities are scheduled.
As cities grow and change, the way people live changes too. Many people want a separate space where elderly parents or kids living at home can still have independence, a space that can be rented out to generate income, or just to rent a smaller, more affordable space. Accessory Dwelling Units, or ADUs, are a low-impact way to meet these needs and expand housing options for people of all ages.
ADUs are self-contained, smaller living spaces that are an extension of an existing property. They are often called mother-in-law suites, granny flats, casitas, backyard cottages, garage apartments or basement apartments. An ADU has its own kitchen, bath and sleeping area, but is not considered a separate property that could be sold on its own.
Scroll down for...
- the History of ADUs,
- ADUs Today,
- the Facts on ADUs in Denver, and
- Additional Resources.
History of ADUs
Accessory dwelling units have long been part of the fabric of Denver, and many other cities around the U.S. Pictured below is the Grant Street Mansion, built in 1892 with an adjacent carriage house. Much like the design of ADUs today, the carriage home provided living quarters above an area for storing a horse-drawn carriage. Historic carriage homes still exist in many older Denver neighborhoods, including Baker, Capitol Hill, Curtis Park, City Park West, Congress Park, Cole, Whittier, Speer, Country Club, West Washington Park, and Platt Park.
Left: Grant Street Mansion circa 1892 (credit Denver Public Library)
Right: Grant Street Mansion circa 2021
Today's ADUs take many forms. They can be built as a free-standing structure in the backyard, could be built above a garage, could be an addition built onto the main home, or could be a converted space within the main home, such as an attic or a basement. The choice of how and where to build an ADU will depend on the property owner's needs and construction budget as well as zoning and building codes.
Explore more ADU styles from around the world >
The Facts on ADUs in Denver
- The Denver Zoning Code regulates height, overall size, setbacks, and more. This zoning code project will look at how these standards impact ADUs.
- An ADU must look “compatible” with the main house. It must be smaller than the zoning allowance for the main house and fit in with the neighborhood. This project will improve how ADUs fit in with different neighborhoods and block patterns.
- The owner of the property MUST live on the property, either in the ADU or in the main house.
- This project will improve how ADUs fit in with different neighborhoods and block patterns. It will not change what uses are allowed in single-unit zone districts.
- All ADUs are reviewed according to the Denver Building and Fire Code to ensure structures are safe and can be accessed by first responders.
AARP: The ABCs of ADUs - A guide to accessory dwelling units
AARP Livable Communities: ADU 'Hot Topics'
5280 Magazine's Guide to Building an ADU
American Planning Association's ADU Collection - Policy guidance from around the country
The foundation for this project is Blueprint Denver, a citywide land use plan that was adopted by Denver City Council in 2019 after three years of public outreach. Thousands of residents helped create the policy recommendations in Blueprint Denver, which included these recommendations for ADUs:
- that barriers to ADU construction be removed,
- that zoning rules be reviewed and adjusted so ADUs fit into a variety of neighborhood contexts.
Read policy recommendation #5 on page 84 of Blueprint Denver.
This project aims to implement the Blueprint Denver recommendations through a community-driven update to the Denver Zoning Code. This project will not change where in the city ADUs are allowed, but will look at how they are designed, how they fit in with different types of neighborhoods and block patterns, and how updates to the zoning code may reduce barriers to creating ADUs.
Read more in the Project Background Report(PDF, 4MB)
Over the next year, city planners will work with residents to develop the specific language for new ADU zoning standards. This work will include public workshops, small focus groups, and surveys to...
- explore the challenges residents currently face in constructing an ADU,
- evaluate possible alternatives for resolving these challenges while achieving the project's goals of reducing barriers and improving design outcomes,
- work with residents and the Community Advisory Committee to recommend a particular strategy, and
- develop and write the zoning standards.
Adoption process: Both the Denver Planning Board and Denver City Council must vote in favor of adopting the new text into the Denver Zoning Code.
Updating the zoning code is a collaborative, community-driven process facilitated by city staff and guided by an advisory committee of residents, local businesses, neighborhood groups, community-serving organizations and other constituencies from across Denver. Once selected, names of individuals on the Community Advisory Committee will be available here.
Senior City Planner
Senior City Planner
Fran Peñafiel - Habla español
Associate City Planner
Submit a question or comment to the project team
Public materials and recordings will be available here as the project progresses.