ADU Regulations in Colorado (CO)
Colorado is rated Easy for ADU construction with an ADU-friendliness score of 91/100 (Very ADU-Friendly). Colorado has a statewide ADU law that sets baseline rules across all municipalities. No owner-occupancy requirement. No additional parking required for ADUs. Colorado passed HB 24-1152 in 2024, requiring all municipalities to allow ADUs on single-family lots. The law prohibits local bans, limits parking requirements, and caps owner-occupancy mandates. Effective 2025 for cities over 1,000 population. ADUs can be rented long-term or short-term depending on local rules.
Full ADU Regulations Summary for Colorado
| ADUs Allowed | Yes |
| Statewide ADU Law | Yes |
| Maximum ADU Size | 1,000 sq ft |
| Owner Occupancy Required | No |
| Parking Required | No |
| Minimum Setback | 5 ft |
| Permitting Timeline | 90 days max |
| Impact Fees | Limited by state law |
| Long-Term Rental Allowed | Yes |
| Short-Term Rental (Airbnb) Allowed | Yes |
| Ease of Building | Easy |
ADU Regulations by City in Colorado
ADU rules can vary by city even within the same state. While Colorado's statewide law sets minimum standards, some cities have additional local provisions. Below are ADU details for 4 cities in Colorado.
Denver
Denver allows ADUs by right on single-family lots. Detached ADUs up to 1,000 sq ft. No owner-occupancy requirement. No additional parking required.
Colorado Springs
ADUs permitted in residential zones per state law. City updated zoning in 2025 for compliance.
Boulder
ADUs allowed on most residential lots. Boulder had permissive ADU rules before the state law. Detached ADUs up to 800 sq ft.
Fort Collins
ADUs permitted by right. City allows both attached and detached ADUs. No additional parking required.
How Colorado Compares to Other States
Below is a comparison of Colorado with five states that have similar ADU-friendliness scores. This comparison helps illustrate where Colorado stands nationally.
| State | Score | Statewide Law | Parking Req? | Owner Occ? | Ease |
|---|---|---|---|---|---|
| Colorado (CO) | 91 | Yes | No | No | Easy |
| Arizona (AZ) | 93 | Yes | No | No | Easy |
| California (CA) | 93 | Yes | No | No | Easy |
| Oregon (OR) | 93 | Yes | No | No | Easy |
| Minnesota (MN) | 88 | Yes | No | No | Easy |
| Vermont (VT) | 95 | Yes | No | No | Easy |
Frequently Asked Questions About ADUs in Colorado
Can I build an ADU in Colorado?
Yes, ADUs are allowed in Colorado. Colorado has a statewide ADU law that requires local jurisdictions to permit ADUs on residential lots. This means your city cannot outright ban ADUs. The ease of building is rated "Easy" with a friendliness score of 91/100.
Do I need to live on the property to have an ADU in Colorado?
No, Colorado does not require owner occupancy for ADUs. You can rent out both the main house and the ADU, which maximizes rental income potential.
How big can an ADU be in Colorado?
The state maximum ADU size in Colorado is 1,000 square feet. Local jurisdictions may set lower limits. Some cities also limit ADU size to a percentage of the primary dwelling (e.g., 50%).
Do I need extra parking for an ADU in Colorado?
No, Colorado does not require additional parking for ADUs. This is a significant advantage, as parking requirements are often the biggest barrier to ADU construction on smaller lots.
Can I rent out my ADU in Colorado?
Yes, long-term rentals of ADUs are allowed in Colorado. Short-term rentals (like Airbnb) are also generally permitted, though your city may have separate short-term rental regulations.
How long does it take to get an ADU permit in Colorado?
The permitting timeline in Colorado is: 90 days max. The statewide law sets maximum review periods that cities must comply with. Actual timelines can be affected by plan review backlogs, inspection scheduling, and the complexity of your project. Pre-approved ADU plans, where available, can significantly speed up the process.
Check ADU Rules for Your City
Use our ADU regulations lookup tool to find the specific rules for your city in Colorado, or browse all 50 states to compare ADU regulations across the country. Remember that local rules may be more specific than state-level regulations.