How does Denver handle ADU permits?
Denver Community Planning and Development reviews ADUs through zoning, building and sewer use and drainage permits. As of October 2026, ADUs are allowed in every zone district that allows new single-unit homes, one per primary dwelling, and they must be built by a licensed contractor.
What did Denver's 2023 ADU update change?
City Council passed ADU amendments on June 5, 2023, effective July 5, 2023. Rules now vary by neighborhood context: urban neighborhoods can have two-story ADUs, suburban ones generally one story. The update also raised the floor area allowed on smaller lots and removed zoning barriers to converting garages and other existing structures.
Does Colorado's ADU law apply to all five cities?
The statute applies to cities with 1,000 or more residents inside a metropolitan planning organization, which covers Denver and its larger suburbs. The Department of Local Affairs lists Denver and Aurora among subject jurisdictions. Most had to comply by June 30, 2025. Local codes are still catching up in places, so we check the code each city is applying when you apply.
What if my home is in unincorporated county land?
Some addresses with a Denver-area mailing city sit in unincorporated Jefferson, Arapahoe or Adams County, where the county, not a city, issues permits. Send the address and we will tell you which office reviews it and whether we can take the project.