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Denver Adopts New Standards for Accessory Dwelling Units

New standards vary based on neighborhood type and will remove barriers to construction of ADUs

DENVER, CO – After more than a year of 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 more about the changes in the project strategy report.

“We’ve heard from Denverites that they want more flexibility in ADU design, both to help reduce costs and to ensure an ADU has the right look and feel in a given neighborhood,” said Laura E. Aldrete, Executive Director of Community Planning and Development. “These zoning code updates respond to the feedback we’ve heard across the city, from suburban homeowners to architects to Councilmembers sharing input from their constituents. We’re excited to implement these changes and look forward to the positive outcomes they will bring to the city.”

“The ADUs in Denver committee successfully agreed on recommendations for building forms which is an important step in allowing for more ADUs across the city,” said Denver Councilwoman Kendra Black, an Advisory Committee member. “I appreciate CPD staff who listened thoughtfully to all perspectives and helped to craft recommendations that we could all get behind. I look forward to future conversations about strategies to increase ADUs in Denver.”

“ADUs are an important element in making sure Denverites have access to a wide variety of housing stock,” said Denver Councilman Chris Herndon, an Advisory Committee member. “These changes will help make ADUs a more attainable and impactful option and give our residents more choices when it comes to living in the city.”

“Currently, 50% of households in west Denver are doubled up, which means a family plus an additional person or persons are living in the same home. This is due to the rapid increase in rental rates in the last ten years and a limited supply of affordable family units,” said Renee Martinez Stone, Director of Denver Housing Authority’s Planning & Data and the West Denver Renaissance Collaborative, and a member of the project Advisory Committee. “These zoning amendments are a good start that will make ADUs more accessible. With the support of DHA, HOST, and Habitat for Humanity Metro Denver, there has never been a better time to build an affordable ADU.” 

Accessory dwelling units are self-contained, smaller living spaces with their own kitchen, bath, and sleeping area 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.

The foundation for this project is Blueprint Denver, a citywide land use plan that was adopted by the 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.

BUILDING COMMUNITY: Denver Community Planning and Development (CPD) is responsible for visionary city planning and ensuring safe, responsible, sustainable building. We’re working hard to make Denver a great place to live, work and play! Visit, and follow CPD on Twitter @DenverCPD and Instagram at @Denver_Landmark