ADU Guide · Verified 2026
Building an ADU in Colorado
Colorado requires ADUs by right, but only in what the law calls "subject jurisdictions": cities and towns of 1,000 or more residents within a metropolitan planning organization, plus certain unincorporated county areas. That covers Denver, Boulder, Fort Collins, Colorado Springs, Pueblo, and most of the Front Range, but leaves rural counties like Garfield fully in local control.
Quick Facts
Statewide floors set by HB24-1152, effective June 30, 2025, C.R.S. 29-35-401 through 405. Your city may be more generous but cannot go below them.
The Three Types of ADU
A real statewide right, with a real geographic limit
HB24-1152 is genuine preemption, but only inside subject jurisdictions, cities and towns of 1,000 or more residents within a metropolitan planning organization. Rural counties outside an MPO, like much of Garfield County, keep full local control, though some have adopted their own permissive rules anyway.
HOAs specifically cannot say no
HB24-1152 makes it illegal for a homeowners association to prohibit an ADU in a subject jurisdiction, a real preemption of private covenants that most states on this list do not reach. An HOA can still require reasonable aesthetic consistency, matching siding or roof pitch, but not an outright ban.
A number that shows how much changed
Before HB24-1152, only about 15% of Denver's residential land was actually open to ADU construction under the old zoning code. The law reopened the rest by right.
State grant money for local pre-approved plans
Colorado's ADUG grant program funds local governments to develop pre-approved ADU plan sets, letting homeowners in participating cities skip custom design and go straight to a faster permit review.
What people get wrong
The most common mistake is assuming HB24-1152 covers all of Colorado. It only reaches subject jurisdictions, cities of 1,000+ inside an MPO. Rural, non-MPO counties are a genuinely different legal category, even within the same state.
From Idea to Move-In: The Timeline
Who Administers It
Building It Yourself? Here's What You'll Need
Planning an ADU? Tools homeowners use in the design and layout phase:
As an Amazon Associate, we earn from qualifying purchases.
Check Your Local Rules
Your city may allow more than the state floor
State law sets the minimum; many Colorado cities and counties are more generous. Browse the full directory of 64 counties and every city in Colorado for local rules, fees, and building department contact details.
Browse the full Colorado directory →Not sure if your project needs a building permit, a zoning approval, or both? See our guide to building permits vs. zoning approval.
Official Sources
ADU law changes frequently and local ordinances add detail. This guide is general information, not legal advice, always confirm with your local building department. Reviewed by the StateDataIndex Editorial Team · Updated September 2026.