Understanding Colorado's New ADU Laws: How to Start Your 2025 ADU Project Now

Urban Rural Designs provides Architectural Design and Construction Management Services to Fort Collins, Denver and the entire Front Range.

Schedule a Free ADU Consultation

Understanding Colorado's New ADU Laws: How to Start Your 2025 ADU Project Now

Urban Rural Designs provides Architectural Design and Construction Management Services to Fort Collins, Denver and the entire Front Range.

Schedule a Free ADU Consultation

What you need to know

In May 2024, the Governor of Colorado, Jared Polis, signed into law House Bill 24-1152 to boost the supply of ADU’s (Accessory Dwelling Units) in urban and close-by suburban areas.  The new law goes into effect June 30, 2025.  The law reduces or removes dimensional, floor area, and even style restrictions which forbade ADU’s or greatly reduced the incentive to build one.  In short, of you have a single family property that has the space to accommodate an ADU, you can begin the process now in some municipalties. 

ADU’s are forecasted to increase a property value by 35%, create intergenerational and age-in-place opportunities, enable child care, the rents are typically lower than small homes, and have low impacts on infrastructure (water, sanitary, electric).   ADU’s use less energy per square foot than a typical home and are thus easier to scale up renewables for energy.  

As homeowners, architects, and builders have been reaching out to their local municipalities to get feedback on what the new local land use / development codes might look like in 2025, some local governments (Counties and Cities) are working to get ahead of the curve and begin processes where ADU projects can start the design and permit documentation process now or in the near future! For instance, The City of Fort Collins staff and City Council are working together to approve a review process, an existing process called a “BDR” review, where staff reviews the site and building design to be in accordance with future HR-1152 law before the new local land use code is actually written.   

We can walk projects through these processes and help people get a jump on ADU projects slated for 2025 construction starts.  Our understanding of the process plus our design strengths of making small spaces efficient, connected, and architecturally exciting. 

Below we have a comparison of anticipated changes in Fort Collins and soon, we will post a breakdown of Larimer County changes.   For any project, we can reach out to the local zoning and building departments and inquire about their process for preparing for HR-1125. 

Understanding Colorado's New ADU Laws Understanding Colorado's New ADU Laws

ADU designed in Fort Collins, CO, in 2018 by Urban | Rural Design.

Current And Future Land Use Code For ADU’s (City Of Fort Collins):

Current Zoning Code

  • Lots under 12,000sf - ADU not allowed in OT (Old Town) Zones
  • Accessory Buildings restricted to 13’ wall heights, 20’ roof heights in most zones, 600sf maximum in OT zones
  • ADU’s allowed in all residential zones that have adequate space and will be restricted by lot size and overall allowable floor area.
  • ADU’s to follow current ADU minimums and maximums (see Detached ADU Floor Area chart below)

Future Zoning Code

  • Lots under 12,000sf – ADU not allowed in OT (Old Town) Zones
  • Accessory Buildings restricted to 13’ wall heights, 20’ roof heights in most zones, 600sf maximum in OT zones
  • ADU’s allowed in all residential zones that have adequate space and will be restricted by lot size and overall allowable floor area.
  • ADU’s to follow current ADU minimums and maximums (see Detached ADU Floor Area chart below)

U|R ADU / Accessory Building Portfolio

Urban Rural Designs provides architectural services to Fort Collins, Denver and the entire Front Range.
Fort Collins ADU 716 Maple - 600sf

Fort Collins ADU

716 Maple - 600sf

Fort Collins ADU - 222 N. Shields Street ADU – 600 sf

Fort Collins ADU

222 N. Shields Street ADU – 600 sf

Larimer County ADU - Continental Drive - Horsetooth Studio

Larimer County ADU

Continental Drive - Horsetooth Studio

Fort Collins ADU - 716 Maple - 600sf

Fort Collins ADU

716 Maple - 600sf

Garage Pop Top ADU - 321 S. Whitcomb Street

Garage Pop Top ADU

321 S. Whitcomb Street

Larimer County ADU - Continental Drive - Horsetooth Studio

Larimer County ADU

Continental Drive - Horsetooth Studio

About Urban | Rural Designs

Since 1994, Brian Majeski has designed and managed projects large and small, commercial and residential, in various parts of the country. He is currently an Associate of the American Institute of Architects (AIA) and serves on the City of Fort Collins Urban Design Working Group, which is part of creating the city's new master plan. He is also serving on the Colorado State University Institute for the Built Environment's (IBE) LENSES Program.

Schedule a Free ADU Consultation
Brian Majeski