Accessory Dwelling Units (ADUs) in Denver

Latest News 

After more than a year working with a community advisory committee, technical experts, neighborhood organizations, City Council members, and the general public to develop zoning code changes for accessory dwelling units (ADUs), Denver’s Department of Community Planning and Development announced the passage of these changes by Denver City Council on Monday, June 5. The zoning changes will go into effect on Wednesday, July 5 and apply to ADU applications received after June 30.

Prior to these zoning code changes, there was a one-size-fits-all approach to ADU design with little variation by neighborhood. The changes allow for nuance based on neighborhood context, and include some of the following updates:

• There is more flexibility to create two-story ADUs in Denver’s more urban areas, making construction more cost effective than the prior 1.5-story height limit.
• In suburban neighborhoods, ADUs will generally be one-story, with rear and side setbacks (the distance from the ADU to the rear and side lot lines) based on neighborhood design.
• The building lot coverage exemption in place for vehicle parking is extended to ADUs, making building one-story ADUs easier. One-story ADUs can better serve occupants who are elderly or disabled.
• In more urban neighborhoods, dormers (vertical windows that rise from a sloping roof) may be allowed to extend past the bulk plane, which is the space a building is allowed to occupy on the lot. Dormers can allow ADUs to better match the architectural features of a neighborhood.
• Zoning barriers that previously limited the conversion of existing structures like garages into ADUs have been removed.
• The maximum floor area of ADUs for smaller lots is increased, allowing these lots the option of building ADUs that can serve a family. This can keep multi-generational families on the same property.

Read the Strategy Report(PDF, 22MB)

Read a 2-page Summary of the Recommendations(PDF, 2MB)

Read the Denver Zoning Code Amendment(PDF, 18MB)

Read the Former Chapter 59 Bridge Amendment(PDF, 64KB)

Learn how community engagement was performed 

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 

See if your property is zoned to allow an ADU

How to Get Involved

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.

Schedule now

Stay Tuned

Sign up to receive email updates as activities such as public workshops, small groups, and surveys are scheduled.

About Accessory Dwelling Units

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. 

Read more in the project background report(PDF, 3MB)

See if your property is zoned to allow an ADU

Constructing Accessory Dwelling Units(PDF, 517KB)

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

ADUs Today

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. 

(JPG, 772KB)

(JPG, 487KB)

(JPG, 549KB)

(JPG, 77KB)

(JPG, 114KB)

 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.

• In single unit zone districts, 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.

• Short-term rentals, including short-term rentals of ADUs, are highly regulated in Denver and require licenses. Review short-term rental laws.

Additional Resources

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

Project Scope and Timeline

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.

Scope 

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, 3MB)

Read more in the Issues Identification Report(PDF, 4MB)

Read more in the Alternatives Report(PDF, 3MB)

Timeline

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...

1. explore the challenges residents currently face in constructing an ADU,
2. evaluate possible alternatives for resolving these challenges while achieving the project's goals of reducing barriers and improving design outcomes,
3. work with residents and the Community Advisory Committee to recommend a particular strategy, and
4. 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. 

Community Advisory Committee and Project Team

Updating the zoning code is a collaborative, community-driven process facilitated by an independent consultant working with city staff and guided by an advisory committee of residents, local businesses, neighborhood groups, community-serving organizations and other constituencies from across Denver.

Project Archive

Public materials and recordings will be available here as the project progresses.