ADU rules in Centennial, CO — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
Centennial approved ADU regulations unanimously in 2024. Interior ADUs are limited to 50% of the primary residence. Detached ADUs cannot exceed 800 sq ft. ADUs must match the primary home's design. Under HB 24-1152, owner occupancy cannot be required, and STRs in ADUs are prohibited except in PUDs.
The Centennial City Council voted 9-0 to approve ADU regulations in 2024. Interior ADUs cannot exceed 50% of the primary residence's total square footage. Detached ADUs are limited to 800 square feet unless a PUD zoning regulation states otherwise. The ADU must match the design, materials, and character of the primary home including roof pitch, siding, windows, and exterior colors. Attached ADUs must have a separate entrance on the side or rear of the property. ADUs must connect to the primary home's water and sewer lines; separate utility taps are not permitted. Under Colorado HB 24-1152, the city cannot require owner occupancy, meaning ADUs can be rented separately. However, STRs in ADUs are prohibited except in PUDs where STRs were previously allowed. ADUs cannot be sold separately from the main home. Administrative approval is required — no public hearings or neighbor vetoes.
Building without a permit: building code violation. Exceeding size limits: zoning violation. Operating an STR in an ADU outside a PUD: code violation.
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Side-by-side rule comparisons with other cities in Arapahoe County.
See how other cities in Arapahoe County handle adu rules.
See how Centennial's adu rules rules stack up against other locations.
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