Colorado House Bill 24-1152 is the most significant piece of ADU legislation in the state's history. Signed by Governor Jared Polis in May 2024, the law took full effect on June 30, 2025, and it fundamentally changed the rules around accessory dwelling unit construction across most of Colorado.
If you are a homeowner in the Denver metro area — including Highlands Ranch, Aurora, Lakewood, Arvada, Centennial, Parker, Littleton, or any other suburb — this law directly affects your ability to build an ADU on your property. Here is what you need to know.
What HB 24-1152 Does
At its core, HB 24-1152 requires "subject jurisdictions" in Colorado to allow at least one accessory dwelling unit on any lot where single-family detached housing is permitted. A subject jurisdiction is any city or county with a population of 1,000 or more that falls within one of Colorado's five Metropolitan Planning Organization boundaries. In practical terms, this covers the entire Front Range: Denver, Boulder, Fort Collins, Colorado Springs, Pueblo, Grand Junction, and every suburb of those metro areas.
Before this law, ADU regulations varied wildly from one city to the next. Some municipalities embraced ADUs. Others effectively banned them through restrictive zoning, minimum lot sizes, or cumbersome approval processes. HB 24-1152 creates a unified baseline that all subject jurisdictions must meet.
Key Provisions of the Law
ADUs Must Be Allowed on All Single-Family Lots
Subject jurisdictions must permit one ADU as an accessory use on any lot zoned for single-family detached dwellings. The ADU can be internal to the primary home (like a basement conversion), attached to it (like an addition), or detached (like a backyard cottage). The jurisdiction cannot restrict which type of ADU a homeowner builds.
Size Requirements: 500 to 800 Square Feet
Municipalities must allow ADUs between 500 and 800 square feet. Jurisdictions may choose to allow larger units — Denver, for example, permits up to 1,000 square feet in some zone districts — but 800 square feet is the minimum maximum that the law requires.
HOAs Cannot Ban ADUs
This is the provision with the most impact in suburban communities like Highlands Ranch, Parker, and Castle Rock, where homeowners associations govern most residential properties. Under HB 24-1152, HOA covenants adopted on or before June 30, 2025 cannot be used to restrict ADU construction in ways prohibited by the law. Covenants created after that date also cannot contain ADU-banning provisions.
HOAs can still enforce what the law calls "reasonable restrictions" — requirements that do not unreasonably increase cost, effectively prohibit construction, or extinguish the ability to build. In practice, this means an HOA can require that your ADU's siding, roof pitch, or color scheme match the primary home. They cannot require architectural styles, materials, or landscaping that exceed the standards applied to the primary dwelling.
Administrative Approval Only — No Public Hearings
ADU applications must be reviewed through an administrative approval process. This means no public hearings, no planning commission votes, and no neighbor veto power. If your plans meet objective zoning standards, the jurisdiction must approve the permit. This provision alone eliminates one of the biggest barriers that previously blocked ADU projects in many Colorado communities.
No Off-Street Parking Mandates (With Limited Exceptions)
In most cases, jurisdictions cannot require a dedicated off-street parking space for an ADU. The only exception is when all three of these conditions are met simultaneously: the zone district required parking for single-family homes as of January 1, 2024; there is no existing parking space on the lot (including a driveway, garage, or tandem space); and the ADU is on a block where the jurisdiction prohibits on-street parking. In practice, this exception applies to very few properties.
Setback Rules
Side setbacks for ADUs cannot be more restrictive than those applied to the primary dwelling on the lot. Rear setbacks cannot be larger than those applied to other accessory structures (like sheds or detached garages) in the same zone, or five feet, whichever is greater. These provisions prevent jurisdictions from using excessive setback requirements to effectively block ADU construction on smaller lots.
What This Means for Denver Metro Homeowners
If you own a single-family home in the Denver metro area, the practical impact of HB 24-1152 is straightforward: you almost certainly have the right to build an ADU on your property. The law removes the patchwork of local restrictions that previously made ADU construction possible in some neighborhoods and impossible in others.
For homeowners in HOA communities — which includes most of Highlands Ranch, Parker, Castle Rock, and many other south Denver suburbs — the HOA provision is transformative. Thousands of properties that were previously ineligible for ADU construction are now open for development.
Denver-Specific Updates
Denver approved citywide ADU allowance across all residential zones in November 2024. The city's regulations include specific building form standards, lot coverage rules, and a requirement that the ADU be positioned in the rear 35 percent of the lot. Denver also requires owner-occupancy at the time of ADU construction completion. The city's zoning code provides detailed dimensional standards homeowners should understand before speaking with designers or builders.
Aurora Updates
The City of Aurora is actively updating its Unified Development Ordinance to comply with HB 24-1152. ADUs will be permitted in R-R, R-1, R-2, R-3, R-4, OA-R1, OA-R2, MU-A, and APZ zone districts. Aurora is also eliminating the public hearing requirement for ADU applications, as mandated by the state law.
State Funding for ADUs
Colorado allocated approximately $8 million in funding to support ADU development, targeted at low- and moderate-income homeowners. The Colorado Division of Local Affairs (DOLA) administers the ADU Grant Program, which launched in August 2025. Additionally, Proposition 123 funds have been directed toward affordable housing initiatives that include ADU development. Some builders in the market are passing through incentives from these programs directly to homeowners.
How to Get Started
If you are considering an ADU on your property, the first steps are straightforward:
- Verify your zoning. Confirm that your property is in a zone district that allows single-family detached dwellings. You can check this through your city's online zoning map or by contacting the planning department.
- Review your HOA documents. Even though HOAs cannot ban ADUs, understanding their reasonable restrictions upfront saves time during design. Pull your CC&Rs and any architectural guidelines.
- Get advisory guidance before hiring a builder. An ADU advisor can help evaluate your lot, identify the best ADU type for your property, estimate likely costs, and prepare you for productive conversations with independent ADU professionals.
Need help navigating the new ADU regulations? We track Colorado ADU laws and Denver metro zoning issues closely. Start with the ADU quiz and we will evaluate your property's ADU potential — zoning, HOA considerations, likely costs, and builder options — at no charge.
Frequently Asked Questions About Colorado's ADU Law
Does the law apply to my city?
If your city has a population over 1,000 and is within one of Colorado's five MPO boundaries, yes. This includes virtually every city and town in the Denver, Boulder, Fort Collins, Colorado Springs, and Pueblo metro areas. The Colorado Division of Local Government maintains a list of subject jurisdictions on their website.
Can my HOA stop me from building an ADU?
No. As of June 30, 2025, HOAs in subject jurisdictions cannot ban ADU construction. They can impose reasonable restrictions around exterior aesthetics — matching siding, roof pitch, colors — but cannot prohibit ADUs outright. If your HOA denies a reasonable ADU application, you may have grounds to challenge that decision under the law.
Do I need to live in the main house or the ADU?
Owner-occupancy requirements vary by municipality. Denver requires the owner to reside on the property at the time ADU construction is completed. Some other jurisdictions have similar provisions. The state law allows municipalities to impose this requirement at the time of construction completion or when applying for a short-term rental permit, but not as an ongoing mandate for long-term rentals.
Can I rent out my ADU on Airbnb?
Short-term rental rules are separate from ADU regulations and vary by city. Denver requires a short-term rental license and owner-occupancy. Other municipalities have different rules. Long-term rentals (30 days or more) are generally permitted across the metro area. Check your specific city's regulations before designing your ADU for short-term rental use.