ADU Rules in Denver, CO (2026)
ADU rules, permit requirements, size limits, and fees for Denver, CO. Source-cited from official municipal code.
Yes, ADUs are allowed in Denver, CO.
Denver, CO permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law actively preempts local restrictions, making ADU approval a streamlined ministerial process. In Denver, the Denver Community Planning and Development (CPD) — Development Services handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Denver.
ADU Size Limits
ADU Size Limits in Denver: Detached ADU: size varies by zoning — see official source (max height: varies — see official source). Attached ADU: size varies by zoning — see official source.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | See official source | See official source |
| Attached ADU | See official source | See official source |
Permit Fees
ADU Permit Fees in Denver: Plan check fee: $1,500–$4,500 depending on project value. Building permit fee: $1,200–$3,500. Impact fees: Denver infrastructure use fees (IUF) may apply — varies by project type and location. School fees: Denver Public Schools impact fees may apply — approximately $3,000–$6,000 for new residential units. Total estimated permit cost: Varies.
| Fee Type | Amount |
|---|---|
| Plan Check | $1,500–$4,500 depending on project value |
| Building Permit | $1,200–$3,500 |
| Impact Fees | Denver infrastructure use fees (IUF) may apply — varies by project type and location |
| School Fees | Denver Public Schools impact fees may apply — approximately $3,000–$6,000 for new residential units |
| Total Estimate | See official source |
Permit Timeline
Denver ADU Permit 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 24-1152) requires ministerial (administrative) approval with no discretionary design review for compliant applications — see official source for current statutory timeline detail. Apply through the Denver Community Planning and Development (CPD) — Development Services online permit portal. Phone: (720) 865-2705.
Setback Requirements
ADU Setback Requirements in Denver: Front setback: follows zone standard. Side setback: no minimum. Rear setback: no minimum.
Parking Requirements
Parking Requirements: No additional off-street parking required for ADUs within 0.25 miles of a high-frequency transit corridor per Colorado HB 24-1152. Denver's 2021 ADU text amendment reduced parking requirements for ADUs citywide. Denver's Blue Line, Light Rail, and BRT corridors provide transit access across much of the city. Consult Denver CPD for specific zone parking requirements.
Restrictions & Requirements
- ADU must comply with Denver Zoning Code Article 4 objective standards for applicable zone
- Maximum 1 ADU per single-family lot per Colorado HB 24-1152 (local ordinance may allow more)
- ADU cannot be sold separately from primary dwelling under single-family zoning
- Short-term rental of ADU requires separate Denver STR license
- ADU must have permanent foundation
- ADU exterior materials should be compatible with primary dwelling per DZC design standards
How Many ADUs Are Allowed?
Number of ADUs Allowed in Denver: Single-family lots: 1 ADU per single-family lot (state minimum per HB 24-1152); Denver local ordinance may allow 1 additional ADU in some zones. Multifamily properties: Additional units per Denver TU (two-unit) and higher zone standards — varies by zone designation. Colorado HB 24-1152 sets a floor of 1 ADU per single-family lot. Denver's own ordinance may be more permissive in certain zones. Two-unit zones (U-TU, E-TU) by definition allow 2 primary units and may allow additional ADUs. Consult Denver CPD for zone-specific maximums.
- Single-Family Lots
- 1 ADU per single-family lot (state minimum per HB 24-1152); Denver local ordinance may allow 1 additional ADU in some zones
- Multifamily Properties
- Additional units per Denver TU (two-unit) and higher zone standards — varies by zone designation
Statewide Preemption
ADU Preemption
Colorado state law preempts local ADU rules — local governments cannot impose stricter standards.
View Colorado preemption detailsState Law & Preemption
State Preemption: Colorado House Bill 24-1152 (signed May 13, 2024; local compliance required by July 1, 2025) requires all Colorado municipalities with population over 1,000 to allow at least one ADU per single-family residential lot by-right. Removes minimum lot size requirements specifically targeting ADU prohibition. Limits parking requirements for ADUs. Creates state enforcement mechanism through Department of Local Affairs (DOLA). Denver already had an ADU ordinance in place prior to state law and has continued to expand ADU allowances. Colorado does not use the California JADU concept.
Historic District Considerations
Historic District Requirements: Denver has 52 historic districts where additional design review may be required for ADU construction. Design review approval is required before obtaining a building permit for properties in historic overlay zones. Denver has 52 designated historic districts as of 2026, including Capitol Hill, Curtis Park, Country Club, and Wyman. Individual Denver Landmarks also exist throughout the city. Certificate of Appropriateness (COA) required for exterior alterations to properties in historic districts or individually designated landmarks. Review by Denver Landmark Preservation Commission. Historic districts search: https://www.denvergov.org/Government/Agencies-Departments-Offices/Community-Planning-and-Development Look up historic district boundaries at: https://www.denvergov.org/Government/Agencies-Departments-Offices/Community-Planning-and-Development
Frequently Asked Questions
Can I build an ADU in Denver?
Yes. Denver, CO allows accessory dwelling units. On a single-family lot you can build 1 ADU per single-family lot (state minimum per HB 24-1152); Denver local ordinance may allow 1 additional ADU in some zones.
How big can an ADU be in Denver?
The maximum size for a detached ADU in Denver is 1,000 square feet.
How long does it take to get an ADU permit in Denver?
The typical ADU permit timeline in Denver is 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 24-1152) requires ministerial (administrative) approval with no discretionary design review for compliant applications — see official source for current statutory timeline detail.. Total estimated permit fees are $3,000–$10,000 in permit fees; school impact fees may add $3,000–$6,000.
Do I need extra parking for an ADU in Denver?
Denver parking rules for ADUs: No additional off-street parking required for ADUs within 0.25 miles of a high-frequency transit corridor per Colorado HB 24-1152. Denver's 2021 ADU text amendment reduced parking requirements for ADUs citywide. Denver's Blue Line, Light Rail, and BRT corridors provide transit access across much of the city. Consult Denver CPD for specific zone parking requirements.
Do I have to live on-site to have an ADU in Denver?
Owner-occupancy requirement in Denver: Colorado HB 24-1152 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.
Source: Denver Zoning Code Article 4 — Residential Zone Districts; Colorado Revised Statutes Title 29 Article 20 (HB 24-1152 codification). Last verified April 5, 2026. View source