Can I Build ADU in Denver, CO? (2026)
Find out if you can build a adu in Denver, CO. Rules, permit requirements, costs, and next steps.
Yes, ADUs are allowed in Denver, CO. California state law ensures by-right approval.
An Accessory Dwelling Unit (ADU) is a secondary housing unit on a residential lot — also called a granny flat, in-law suite, or backyard cottage. In Denver, CO, ADUs are permitted by right under state law, making them one of the most accessible ways to add housing on your property. ADUs can be detached, attached to the main home, or created by converting an existing garage or accessory structure.
ADU Rules in Denver
ADU Rules in Denver: Detached ADU max size: 1000 sq ft. Attached ADU max size: 1000. Setbacks: 5 ft side, 5 ft rear. Owner-occupancy: Colorado HB 24-1175 prohibits local owner-occupancy requirements for ADUs. Denver eliminated its owner-occupancy requirement as part of its ADU ordinance updates in 2021. Neither the primary dwelling nor the ADU is required to be owner-occupied. Short-term rental of an ADU requires a Denver Short-Term Rental license.. State preemption applies: CO law requires Denver to approve compliant ADUs by right.
Costs & Fees
ADU permits in Denver: Total estimated permit cost: $3,000–$10,000 in permit fees; school impact fees may add $3,000–$6,000. Contact the Denver Community Planning and Development (CPD) — Development Services for current fee schedule.
Timeline
Denver CPD (Community Planning and Development) processes ADU permits. Standard ADU: 4-8 weeks plan review. Denver offers expedited review for ADUs meeting pre-approved design standards. Construction typically 4-10 months. State law (HB 24-1175) requires ministerial approval within 60 days for compliant applications.
Next Steps
Next steps for building an ADU in Denver: 1. Review full ADU rules including size limits, setbacks, and parking. 2. Apply for an ADU permit through the Denver Community Planning and Development (CPD) — Development Services at https://www.denvergov.org/Government/Agencies-Departments-Offices/Community-Planning-and-Development/Building-Permits/Online-Permits. 3. Hire a licensed contractor familiar with CO ADU requirements.
Denver Community Planning and Development (CPD) — Development Services
Frequently Asked Questions
Can I build an ADU in Denver?
Yes. Colorado HB 24-1175 (2024) requires Denver to allow at least one ADU per single-family lot by-right. Denver had an ADU ordinance in place before state law and has continued to expand ADU allowances. You can build a detached ADU up to 1,000 sqft in most single-family zones. No owner-occupancy requirement. Building permit from Denver CPD required. Colorado does not have the California JADU concept.
What is Colorado HB 24-1175 and how does it affect Denver?
Colorado HB 24-1175 (effective August 7, 2024) requires all Colorado municipalities with population over 1,000 to allow at least one ADU per single-family residential lot by-right. It removes minimum lot size requirements targeting ADU prohibition, limits parking requirements for ADUs, and creates state enforcement. For Denver, it reinforces and expands existing ADU allowances that were already in place through the city's own ordinance.
Do I need a permit for a home business in Denver?
Yes. A Denver Business License and Home Occupation Permit (approximately $50) are required to operate a business from your Denver home. You may have up to 2 customer visits per day, no non-resident employees, and no external evidence of business. The Colorado Cottage Food Act allows home-based food production (baked goods, jams, etc.) with CDPHE registration and no revenue cap. Note Denver's altitude (5,280 ft) can affect some food production processes.
Can I do short-term rentals on Airbnb in Denver?
Yes, with a Denver Short-Term Rental License ($100/year). The property must be your primary residence. Airbnb automatically collects and remits Denver and Colorado lodging taxes (approximately 10.75% combined). Display your license number on your listing. Operating without a license carries fines of up to $999 per violation. Only one STR license per person — Denver enforces this strictly.
What are the setbacks in Denver's U-SU-A zone?
In Denver's U-SU-A zone (Urban Single-Unit A, one of the most common single-family zones), the front setback is 20 feet, side setbacks are 5 feet on each side, and the rear setback is 20 feet. Maximum lot coverage is 45% and maximum height is 35 feet (3 stories). Use Denver's online zoning map or contact Denver CPD to confirm your specific parcel's zone designation and applicable standards.
Is solar required on new homes in Denver?
No. Colorado does not have a statewide new-construction solar mandate like California. Solar is strongly encouraged — Denver's 300+ annual sunny days create excellent solar production, and Xcel Energy offers net metering. The federal Investment Tax Credit (ITC) provides a 30% credit. Colorado also has a state income tax credit for residential solar. Denver's Green Building Ordinance applies to large commercial/multifamily buildings over 25,000 sqft but not single-family homes.
How do I look up the zoning for my Denver property?
Use Denver's online zoning map at https://www.denvergov.org/Government/Agencies-Departments-Offices/Community-Planning-and-Development/Denver-Zoning-Code/Zoning-Map. Enter your address to find your Denver Zoning Code zone designation. You can also contact Denver CPD Development Services at (720) 865-2705 or visit the Webb Municipal Building at 201 W. Colfax Ave, Denver. The Denver interactive zoning map shows zone districts, overlay zones, floodplains, and historic districts.
Source: Denver Community Planning and Development (CPD) — Development Services — Building Regulations. Last verified April 5, 2026. View source