Everything homeowners need to know about building an accessory dwelling unit in Denver - size limits, setbacks, permits, and how the city's own ADU program now lines up with Colorado's new statewide ADU law.
Last verified: August 2026
9/10 · Very ADU-friendly
1,000 sq ft*
Max ADU size
24 ft
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes the Denver Zoning Code's ADU standards, as updated by the city's December 2024 citywide text amendment and Colorado's statewide ADU law (HB 24-1152), for general reference - it is not legal advice. Regulations change; always confirm current requirements with Denver Community Planning & Development (CPD) before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new build or garage conversion)
Up to 1,000 sq ft on larger lots; smaller lots are capped lower (roughly 650 sq ft under 6,000 sq ft, and roughly 864 sq ft on 6,000-7,000 sq ft lots)
24 ft; generally 1.5 stories, with 2-story ADUs allowed in more urban zone districts
Must be sited within the rear 35% of the lot, with at least a 5 ft rear setback
Sized within the primary structure - no separate detached-style footprint cap
Same as primary structure
Common approach for a basement or above-garage conversion
Allowed zoning districts
Following a citywide text amendment (CB24-1303) effective December 16, 2024, ADUs are allowed by right in every zone district that allows a single-unit dwelling - covering roughly 70% of Denver's residential land area, up from about 36% before the update - with no rezoning needed in eligible zones. Confirm your parcel's zoning with Denver Community Planning & Development (CPD).
Additional standards
Setbacks, parking & other rules
Setbacks
Detached ADUs must sit within the rear 35% of the lot with at least a 5 ft rear setback; side and front setbacks generally follow the underlying zone district's standard house setbacks
Parking
No dedicated off-street parking is required for the ADU itself; Colorado's HB 24-1152 also bars most parking mandates statewide
Units per lot
1 ADU permitted per single-unit lot, in addition to the primary dwelling
Owner-occupancy
Not required. Denver's citywide text amendment (effective December 2024) and Colorado's HB 24-1152 (fully effective June 30, 2025) both remove owner-occupancy as a condition of building or renting an ADU. This is a recent change - confirm current status with CPD, especially if you're relying on an older source
Building code
Must meet Denver Building and Fire Code dwelling-unit standards
Rental license
A city rental license is required for most long-term residential rentals, including ADUs; short-term rental licensing has separate rules and may still require owner-occupancy of the primary residence
Ordinance history
How Denver's ADU rules got here
2023"ADUs in Denver" zoning update. A text amendment effective July 5, 2023 expanded where ADUs were allowed and simplified design standards, though owner-occupancy and zone-by-zone limitations remained in place.
2024Colorado passes HB 24-1152. The state legislature approved a statewide ADU law requiring "subject jurisdictions" - cities of 1,000+ residents inside a metropolitan planning area, including Denver - to allow at least one ADU by right per single-family lot and to drop owner-occupancy and most parking requirements.
2024Denver goes citywide. On November 18, 2024, City Council passed a citywide ADU text amendment (CB24-1303), effective December 16, 2024, extending by-right ADU eligibility to roughly 70% of Denver's residential land (up from about 36%), removing the owner-occupancy requirement, and allowing 2-story ADUs in more urban zone districts.
2025State law takes full effect. Colorado's HB 24-1152 became fully effective June 30, 2025, reinforcing Denver's local changes with a statewide floor: by-right ADUs, administrative-only approval, and no owner-occupancy or blanket parking mandates for subject jurisdictions statewide.
Denver had already built much of its own ADU program before the state law arrived, so HB 24-1152 mostly reinforced changes the city had made on its own - unlike many smaller Colorado cities and suburbs, where the state law forced ADUs to be allowed for the first time.
Permit process
How Denver ADU permitting works
1
Confirm zoning eligibility
Check whether your property is in a zone district that allows single-unit dwellings using Denver's zoning map; if so, an ADU is allowed by right and rezoning isn't required.
2
Hire a licensed contractor
Denver requires ADU permit applications to be filed by a licensed contractor rather than the homeowner directly, with limited exceptions.
3
Prepare your plan set
Site plan, building elevations, structural plans, and manufacturer cut sheets as needed, plus documentation confirming the status of the primary structure.
4
Apply through Denver's e-permits portal
Submit for zoning, building, and Sewer Use and Drainage Permit (SUDP) review together as a "Single Family/Duplex Residential" project.
5
Plan review & permit issuance
CPD reviews for zoning and building code compliance; trade permits (electrical, plumbing, mechanical) are issued once the residential construction permit is active.
6
Inspections & certificate of occupancy
Schedule required inspections through construction and obtain your Certificate of Occupancy before anyone moves in; the ADU also needs its own address.
Fees and review times vary by project value and CPD's current workload - confirm current numbers with Denver Community Planning & Development before budgeting.
Budgeting
What it costs to build an ADU in Denver
Garage conversion
Roughly $75,000-$160,000, the least expensive path since the shell already exists
Basement conversion
Roughly $110,000-$210,000, depending on existing ceiling height and utility access
New detached ADU
Roughly $160,000-$300,000+ for a code-compliant, fully insulated freestanding unit
Building permit & SUDP fees
Commonly in the $5,000-$8,000 range combined for a typical ADU project, including the Sewer Use and Drainage Permit
Water & sewer tap fees
A Denver Water system development charge plus a separate sewer tap fee, together commonly landing in the high thousands to low tens of thousands of dollars depending on your water district
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, utility access, and finishes. Denver ADUs are exempt from the city's Affordable Housing Linkage Fee, which helps offset some of the tap and permit costs above.
Before you apply
Tips for a smooth approval
Check your lot size before assuming you can build 1,000 sq ft. Denver's footprint caps step down on smaller lots, so confirm the number for your specific lot with CPD before you design.
Hire your contractor before you apply. Denver requires ADU permits to be submitted by a licensed contractor, not the homeowner, so line this up early.
Budget for tap and SUDP fees separately from your building permit. These utility-related charges are billed apart from standard permit fees and are easy to underestimate.
Confirm current owner-occupancy status with CPD. The requirement was only removed citywide in December 2024 and reinforced by state law in mid-2025, so some older articles and even some older city documents may not reflect it yet.
Ask about 2-story eligibility if you're in a more urban zone district. Denver's 2024 update allows taller, 2-story ADUs in some areas, which can make a tight lot much more workable.
FAQ
Common questions
Do I need to live on the property to build an ADU in Denver?
No, not anymore. Denver removed its owner-occupancy requirement citywide effective December 16, 2024, and Colorado's HB 24-1152 reinforced that statewide as of June 30, 2025. Confirm current status with CPD, since this is a recent change.
How many ADUs can I build on one lot in Denver?
One ADU is allowed per single-unit lot, in addition to the primary dwelling.
Do I need extra parking for an ADU?
No dedicated off-street parking is required for the ADU itself, and Colorado's statewide ADU law also bars most parking mandates.
What's the maximum size for a detached ADU in Denver?
Up to 1,000 sq ft on larger lots, though smaller lots are capped lower (roughly 650-864 sq ft depending on lot size), with a 24 ft height limit.
How long does the permit process take?
Timelines vary with project value and CPD's current workload; confirm current review times with Community Planning & Development before budgeting your schedule.
How much does an ADU cost to build in Denver?
Garage conversions run roughly $75,000-$160,000, basement conversions roughly $110,000-$210,000, and new detached units roughly $160,000-$300,000+, based on local contractor estimates and regional reporting - not counting permit and utility tap fees.
Does Denver's ADU program predate Colorado's statewide law?
Yes. Denver had its own ADU zoning program and a 2023 expansion before Colorado passed HB 24-1152 in 2024; the state law, fully effective June 30, 2025, mainly reinforced and extended changes Denver had already made locally.
Do I need to be a licensed contractor to apply for an ADU permit?
You don't need to be a contractor yourself, but Denver requires the permit application to be filed by a licensed contractor rather than the homeowner directly, with limited exceptions.
Can I rent my ADU out on Airbnb or a short-term rental platform?
Denver regulates short-term rentals separately from long-term rental licensing, and short-term rental rules may still require owner-occupancy of the primary residence even though long-term ADU rentals no longer do. Confirm current short-term rental requirements before finalizing your plans.
