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: up to 1000 sq ft (max height: 24 feet). Attached ADU: 1000 sq ft. Colorado does not use the California JADU (Junior ADU) concept. Denver allows detached and attached ADUs up to 1,000 sqft per Denver Zoning Code standards. ADU floor area is also limited to 50% of the primary dwelling's floor area in some zones. Check zone-specific regulations in the Denver Zoning Code for the specific parcel zone designation.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 1000 sq ft | 24 feet |
| Attached ADU | 1000 sq ft | Same as primary dwelling height limit per zone |
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: $3,000–$10,000 in permit fees; school impact fees may add $3,000–$6,000. Denver permit fees are valuation-based. Full fee schedule: https://www.denvergov.org/Government/Agencies-Departments-Offices/Community-Planning-and-Development/Building-Permits/Fees
| 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 | $3,000–$10,000 in permit fees; school impact fees may add $3,000–$6,000 |
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 24-1175) requires ministerial approval within 60 days for compliant applications. 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: Same as zone standard. Side setback: 5 feet. Rear setback: 5 feet. Detached ADU setbacks: 5 ft minimum from side and rear property lines in standard single-unit zones per Denver Zoning Code. Front setback follows zone standard. Corner lots have additional street-side setback requirements. ADU may be located in rear yard as primary placement. Alley-accessed properties: ADU may be built close to alley.
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 24-1175. 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 24-1175 (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 24-1175); 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 24-1175 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 24-1175); 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
State Law & Preemption
State Preemption: Colorado House Bill 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. 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/Historic-Preservation Look up historic district boundaries at: https://www.denvergov.org/Government/Agencies-Departments-Offices/Community-Planning-and-Development/Historic-Preservation/Historic-Districts
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 24-1175); 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 24-1175) requires ministerial approval within 60 days for compliant applications.. 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?
No, Denver does not require additional parking for ADUs.
Do I have to live on-site to have an ADU in Denver?
No, owner-occupancy is not required for ADUs in Denver.
Source: Denver Zoning Code Article 4 — Residential Zone Districts; Colorado Revised Statutes Title 29 Article 20 (HB 24-1175 codification). Last verified April 5, 2026. View source