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Zoning Guide

ADU Rules in Fort Collins, Colorado

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ADU Rules in Fort Collins, Colorado

Fort Collins is home to Colorado State University and is consistently ranked as one of the best places to live in the US. The city has updated its Land Use Code to encourage ADU development as part of its housing affordability strategy. ADUs are permitted by right in most residential zones.

Permitted ADU Types

  • Detached ADU (Carriage House): A standalone structure on the same lot
  • Attached ADU: Connected addition with own entrance and kitchen
  • Garage Conversion: Converting existing detached garage

Size Limits

ADU Type Maximum Size
Detached ADU 1,000 sq ft or 50% of primary dwelling
Attached ADU 1,000 sq ft or 50% of primary dwelling
Garage Conversion Existing footprint

Setbacks

  • Front: Must comply with base zone
  • Side: 5 feet minimum
  • Rear: 5 feet minimum
  • Alley: Reduced setbacks may apply for alley-facing ADUs

Height

  • Detached ADU: Maximum 20 feet in most residential zones
  • Cannot exceed height of primary dwelling

Owner Occupancy

Fort Collins has been relaxing owner-occupancy requirements. Contact the Planning Department for the most current requirements.

Near-Campus Considerations

Fort Collins has occupancy regulations in neighborhoods near CSU designed to manage rental density. Check for any occupancy overlay requirements for your specific property.

Parking

One additional off-street parking space required per ADU in most zones. Transit-served areas may have reduced requirements.

Permit Process

  1. Check Land Use Code: Verify at Fort Collins Development Review
  2. Pre-application meeting: Optional — available through Planning
  3. Submit plans: Architectural and site plans
  4. Plan review: Administrative review
  5. Building permit: Issued after approval
  6. Inspections and CO: Required before occupancy

Contact

Fort Collins Development Review 281 N. College Ave, Fort Collins, CO 80524 Phone: (970) 221-6750 Website: fcgov.com/developmentreview

Disclaimer: Verify current requirements with Fort Collins Development Review. ADU regulations have been updated recently.

More about Fort Collins Zoning

Sources

  1. Fort Collins Land Use Code — Accessory Dwelling Units·library.municode.com·Accessed 2026-04-07·Direct link
  2. City of Fort Collins Planning Department·fcgov.com·Accessed 2026-04-07·Direct link

FAQ

Are ADUs allowed in Fort Collins, Colorado?
Yes. Fort Collins, home to Colorado State University, has updated its Land Use Code to be more ADU-friendly. ADUs are permitted by right in most low-density residential zones.
What is the maximum ADU size in Fort Collins?
In Fort Collins, detached ADUs are limited to 1,000 square feet or 50% of the primary dwelling's floor area, whichever is less.