ADU laws in Colorado

In plain words

Colorado has a statewide ADU law. It passed in 2024, and its main rules began June 30, 2025. An ADU (accessory dwelling unit) is a second, smaller home on the same lot as a house. It can be inside the house, attached to it, or a separate backyard building.

The law covers 66 cities and towns in the state's urban regions, plus Highlands Ranch. That includes Denver, Colorado Springs, Aurora, Fort Collins and Grand Junction. Most rural areas, mountain towns and county land outside cities are not covered. There, local zoning still decides. Zoning is the set of local rules about what can be built where.

In covered places, the city must allow one ADU anywhere a single-family house is allowed. The project still has to meet local building and safety rules. City staff check your plans against written rules, with no public hearing. That is what people mean by "by right."

Covered cities cannot require you to keep living on the property. That kind of rule is called "owner occupancy." In most cases they cannot make you build a new parking space. They must allow ADUs between 500 and 750 square feet. They also cannot demand side or back setbacks larger than the law allows. A setback is the required gap between a building and the property line.

An HOA is a homeowners association. HOA rules that block ADUs are void in covered areas, though an HOA can still set reasonable conditions. Cities can still regulate short-term rentals. They can also charge normal impact fees, one-time charges that help pay for roads, parks and utilities. Some lots are exempt, such as lots in a floodplain or without public water and sewer. If local rules and your property allow it, the process should be a staff-level permit.

The rules at a glance

What to do next

1. Check whether your city or town is on DOLA's list of HB24-1152 subject jurisdictions, or is a certified ADU Supportive Jurisdiction.
2. Read your city's current ADU code and fee schedule; many cities rewrote theirs in 2024-2025, and details such as height and design still vary.
3. Check whether your lot is exempt: floodway or 100-year floodplain, no public water and sewer (or a well permit that cannot serve another unit), or an individually listed historic property.
4. Ask your water and sewer provider for a capacity statement, and request a pre-application meeting with your city if one is offered.
5. If you live in an HOA or condo association, get its ADU rules in writing and note when each rule was adopted; outright bans are void in covered areas, and elsewhere a ban added on or after July 1, 2024 cannot block an ADU that zoning allows, but reasonable conditions and some older covenants may still apply.
6. If your household is low or moderate income and your city is a certified ADU Supportive Jurisdiction, ask a lender about CHFA's ADU finance programs.

Grants, loans and tax breaks

• Accessory Dwelling Unit Grant Program (ADUG): State grants from the Department of Local Affairs to local governments certified as ADU Supportive Jurisdictions. Money can pay for pre-approved ADU plans, homeowner technical help, or waiving and reducing ADU fees. Round 3 is open to local governments from September 28 to October 23, 2026. Homeowners benefit indirectly through their city or county. Program page
• CHFA ADU Finance Programs: Authorized by HB24-1152 and run by the Colorado Housing and Finance Authority through participating lenders: an ADU Interest Rate Buydown Program and an ADU Credit Enhancement Program for low- and moderate-income borrowers, plus an ADU Relending Program for nonprofits, housing authorities and CDFIs. Available only in certified ADU Supportive Jurisdictions; homeowners apply through a lender. Program page

What your town still decides

Inside covered jurisdictions, the state rules are a floor: cities still write the detailed ADU code (height, design standards that are not 'restrictive' under the law, utility and life-safety codes) and many rewrote their codes in 2024-2025. Covered jurisdictions had to file a compliance report with DOLA by June 30, 2025 (or by December 30, 2025 with an approved extension). Outside the covered areas, which include most rural and mountain towns, the Eastern Plains, the Western Slope outside the Grand Junction area, and most unincorporated county land, each city, town or county still decides whether and how to allow ADUs. Owners in covered areas may be asked to show they live on the parcel when they apply to build or convert an ADU (not when the ADU is built together with a new house), but the city cannot require the owner to keep living there. HOA declarations, bylaws and rules in covered or certified areas cannot restrict ADUs in ways the law forbids; only 'reasonable restrictions' that do not effectively prohibit an ADU or unreasonably raise its cost are allowed. Outside covered areas, a separate 2024 law (SB24-174) stops any HOA or condo association from adding a new ADU ban or restriction after July 1, 2024 where local zoning allows ADUs, but older covenant restrictions there still stand. Executive Orders D 2025 005 and D 2025 011 tie priority for some state funding to compliance with HB24-1152 and other 2024 land-use laws. A May 2025 lawsuit by several home-rule cities (later joined by Colorado Springs) challenged the 2024 parking and transit-housing laws and Executive Order D 2025 005, not the ADU law (per the Colorado Municipal League and later news coverage).

Examples of local rules

• Denver: City Council passed a citywide ADU measure on November 18, 2024 (in effect December 16, 2024) that allows ADUs in all residential areas, about 70% of the city's land, up from 36%. It also implements HB24-1152, including updating the old rule that an ADU could not be used if the owner moved away. Each zone district has its own ADU setback, height and bulk standards. The city does not enforce HOA rules. Source
• Colorado Springs: Ordinance 25-45 (approved April 8, 2025) allows one attached, detached or integrated ADU on any lot with a single-family home, permitted through a building permit. Size is capped at 50% of the main house or 1,250 sq ft, whichever is less, with 750 sq ft allowed when the house is under 1,500 sq ft. Detached and attached ADUs are not allowed in the city's wildland-urban interface overlay (integrated ones are). An ADU cannot also be a short-term rental. Applicants sign an owner residency affidavit, and city impact fees apply. Source
• Fort Collins: Since February 2025, ADUs are allowed in all zone districts if the property meets city standards. Most lots may add one ADU. Detached ADU sizes: up to 750 sq ft when the main home is under 1,667 sq ft, otherwise up to 1,000 sq ft or 45% of the home, whichever is less; converted accessory buildings up to 800 sq ft. Detached ADUs must sit behind the front wall of the house and may not be taller than the main building. Source

What we’re still confirming

• Some cities still bar ADUs on safety grounds, such as Colorado Springs in its wildfire-risk overlay; how the state views those exceptions isn't confirmed, so check where your lot sits.
• How much money is left in the state's ADU grant program (ADUG) and CHFA's ADU finance programs isn't confirmed; ask your city or a participating lender.

Laws, bills and citations

This is general information, not legal advice. Your town, village, city or county decides what can be built on your property. If something here looks out of date, email the team.