If you’ve ever dreamed of adding a backyard cottage, a rental suite above your garage, or a small home for aging parents, Fort Collins just became an ADU-friendly city in Colorado—thanks to new statewide legislation and a significant local code update.
Colorado passed House Bill 24-1152 (HB24-1152), a sweeping law requiring all jurisdictions within metropolitan planning organizations—including Fort Collins—to allow Accessory Dwelling Units (ADUs) on any lot where a single-family home exists or could be built. The City of Fort Collins responded by amending its Land Use Code to comply, effectively opening the door for thousands of property owners to create new, flexible housing options.
What Is an ADU and Why Does It Matter?
An ADU, often called a “granny flat,” “carriage house,” or “in-law suite,” is a secondary housing unit located on the same lot as a primary home. It can be attached, detached, or converted from an existing structure like a garage.
Under the new law:
- ADUs are now permitted on any lot zoned for single-family dwellings.
- Setback and design standards for ADUs cannot be more restrictive than those applied to the primary home.
- No additional parking spaces or owner-occupancy requirements can be imposed.
- Existing accessory buildings can be converted to ADUs.
- The minimum allowable ADU size is 750 square feet.
- Applications must be reviewed based solely on objective criteria without public hearings.
This law removes barriers that previously made building ADUs difficult or expensive, supporting more diverse, affordable housing options in Fort Collins.
What Does It Cost to Build an ADU in Fort Collins?
Like any construction project, costs can vary widely based on design, site conditions, and finishes. However, according to city documents, a recently proposed plan for a retrofit ADU project in Fort Collins total approximately $25,571.78 for fees alone. These include everything from electrical and utility connection charges to city and county sales taxes, parkland fees, and capital expansion fees.
Beyond fees, actual construction costs can range from $125,000 to $350,000 or more, depending on whether you are converting an existing structure or building new. Costs have risen sharply in recent years.
To help offset some of these costs, the city is working to become an ADU Supportive Community, which would make it eligible for grant funding from the Colorado Department of Local Affairs (DOLA). This could allow Fort Collins to:
- Waive or reduce ADU-related fees.
- Provide pre-approved ADU plans.
- Offer technical assistance to homeowners.
What’s the Timeline to Build an ADU?
The process to build an ADU in Fort Collins generally takes about 12 months from start to finish:
- 2–3 months for the Basic Development Review (BDR) process. This includes review of the ADU’s exterior design and site placement.
- 6–8 weeks for the Building Permit Review. This focuses on the interior layout, structural integrity, and compliance with safety codes.
- 4+ months for construction and final inspections.
Overall, you should plan for a full year to go from concept to completion. The good news is the process is now entirely administrative—no public hearings, neighborhood meetings, or special approvals required.
Why Should Homeowners Consider an ADU?
With Fort Collins’ ongoing affordability challenges and housing shortage, ADUs offer a practical solution:
- Rental income to offset mortgage costs.
- Multigenerational living options.
- Long-term property value increase.
- Flexibility to age in place or downsize.
Additionally, Fort Collins is exploring pre-approved ADU designs that could save homeowners both money and time in the design and permitting process.
The passage of HB24-1152 is a game-changer for property owners and renters alike. Whether you’re looking to create a rental unit, house family members, or build wealth through real estate, the new ADU rules in Fort Collins unlock opportunities that were previously out of reach.
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