Commerce City homeowners who have been eyeing a backyard cottage or in-law suite just got the official go-ahead. The city now lets residents build accessory dwelling units, or ADUs, on single-family lots, opening the door to small, self-contained homes that can serve as rentals, guest units, or space for multigenerational living. City officials emphasize that any ADU has to stay clearly secondary in size and design to the main house.
What changed
The policy shift stems from an overhaul of the city’s 2025 Land Development Code. The updated code, adopted last fall and effective as of November 2025, explicitly permits ADUs in zoning districts that already allow single-family homes, according to Commerce City. The city has published step-by-step guidance and application information on its development and building webpages for homeowners ready to start planning an extra unit.
Rules to know
Under the new framework, ADUs fall into three categories: attached, contained, or detached, and each single-family lot is limited to one ADU, as reported by KDVR. The outlet notes that attached ADUs must share at least eight feet of common wall with the main dwelling and cannot be entirely carved out of existing living space, while a contained ADU sits fully within the footprint of the primary home. KDVR also reports that permit applications must include a valuation that shows the total cost of materials, labor, and equipment used for the project.
How to apply
Homeowners need to secure a building permit through the city’s Building Safety Division, with plans submitted electronically through the eTRAKiT portal. For questions, the division lists permit contacts at 303-289-3790 and [email protected], per Commerce City. City materials spell out typical limits on height, maximum unit size, setbacks from property lines, utility connections, and safety requirements such as exits and fire protection.
Legal context
Commerce City’s move lines up with statewide rules that push many metro-area jurisdictions to allow ADUs and to approve them through an administrative process. The Division of Local Government notes that covered communities generally cannot require owner occupancy or extra parking for ADUs, while they can still enforce reasonable dimensional standards and safety codes, per Colorado DLG. The state has also created grant and financing programs to encourage ADU construction, while allowing cities like Commerce City to keep these units clearly subordinate to the primary home in both scale and appearance.
