Do I Need a Permit to Build an ADU in Denver, CO?

ADU-specific overview

What makes this different from a simple accessory structure

Pulled from the city's ADU guidance and linked code references.

Permit type: Residential building permit (new construction or addition) through Denver Building & Fire Code, with concurrent zoning review by Denver CPD. AADU and DADU both follow the standard residential permit path.
Maximum size: DADU: 864 square feet of gross floor area, or 50% of the primary dwelling's gross floor area, whichever is greater (capped at 864 sqft). Maximum height 24 feet. AADU: generally governed by the 50%-of-primary-dwelling ratio and zone-district development standards.
Setbacks: DADU: minimum 5 feet from rear lot line and 5 feet from each side lot line under Denver Zoning Code 5.4. Front setback must meet the zone-district standard. Confirm current requirements for the specific zone district with Denver CPD.
Owner occupancy: No owner-occupancy requirement under Denver Zoning Code 5.4. Colorado HB24-1152 (2024) also prohibits municipalities from requiring owner occupancy as a condition for ADU approval.
Parking: No additional off-street parking is required for an ADU in Denver's urban and suburban zone districts under current Denver Zoning Code standards.
Utilities: ADU utility connection options (shared vs. separate) should be confirmed with Denver Water and Denver Public Works during design. New water tap or sewer connection triggers Denver Water and Metro Wastewater fees, which can be substantial.
JADU distinction: Denver does not use a California-style JADU designation. ADUs created within the existing primary structure are treated as Attached ADUs under Denver Zoning Code 5.4 rather than a separate junior-unit category.

Colorado HB24-1152 (2024) is a statewide mandate requiring all Colorado municipalities to allow ADUs by right in any zone permitting single-family use, effective January 1, 2025.
Denver's 2019 ADU text amendment expanded ADU allowances across more residential zone districts before the state law passed.
Denver CPD's ADU page and one-page ADU summary document provide the most current size, setback, and design standard references.

Fees

Estimated city fees

Baseline for a simple permitted adu: Denver permit and plan review fees are valuation-based. A new detached ADU valued at $150,000–$250,000 typically generates $2,000–$5,000+ in combined permit and plan review fees, not including utility tap fees. Verify current amounts at denvergov.org/permits.

Fee	Amount	Notes
Building permit fee	Valuation-based	Denver Building & Fire Code charges permit fees based on declared construction valuation. Use Denver's permit fee schedule at denvergov.org/permits for current amounts.
Plan review fee	65% of permit fee (typical)	Denver charges a plan review fee as a percentage of the building permit fee. Verify the current percentage and any minimum with Denver Building & Fire Code at application.
Use and occupancy tax	Project-specific	A Denver use and occupancy tax may apply to construction materials and labor. Verify with Denver's Treasury division.
Water and sewer tap/connection fees	Project-specific	If the ADU requires a new Denver Water tap or sewer connection, separate tap fees and Metro Wastewater fees apply and can be significant. Confirm with Denver Water and Denver Public Works.

Documents

Required documents

Completed building permit application submitted through Denver's Community Planning and Development eTRAKiT portal.
Site plan showing lot lines, existing dwelling, proposed ADU footprint, setback dimensions, existing and proposed impervious surfaces.
Architectural plans including floor plans, elevations, cross sections, and roof plan.
Structural plans or engineering calculations for non-prescriptive elements.
Energy code compliance documentation (Colorado Energy Code / IECC compliance).
Stormwater/drainage review materials if the project exceeds Denver's impervious-surface threshold.
Colorado licensed contractor information if a contractor is performing permitted construction work.

Timeline

Typical timing

Plan review: 4–8 weeks for standard plan review; concurrent review by zoning and building is standard practice
Total cycle: 8–20 weeks typical from submittal to permit issuance; total project time including construction and inspections varies

Denver CPD posts current plan review queue estimates on its website. Correction rounds and utility coordination can extend timeline. Pre-application meetings with CPD are available.

Process

How the permit process works

Confirm the zone district allows an ADU Use Denver's online zoning map to verify the parcel is in an SU or TU zone district. Under Colorado HB24-1152, ADUs are now also allowed by state law in any Denver zone that permits single-family use.
Determine ADU type and design Decide between a detached ADU (a new separate structure) or an attached ADU (addition to or conversion within the primary dwelling). Confirm the design meets Denver Zoning Code 5.4 size, height, and setback requirements.
Prepare the permit package Assemble site plan, architectural drawings, structural plans (if needed), energy code compliance documentation, and any stormwater materials required by Denver Public Works.
Submit through Denver's eTRAKiT portal File the building permit application and upload plans through Denver's online permit portal (eTRAKiT). Pay the plan review fee at intake.
Complete plan review and address corrections Denver Building & Fire Code reviewers and Denver Community Planning and Development (CPD) zoning staff will review the submittal. Address any correction notices to advance the application.
Pay fees and pick up the permit After plan approval, pay remaining permit fees. Denver issues the permit; post it visibly at the job site before construction begins.
Complete inspections and close out Schedule required inspections (foundation, framing, insulation, mechanical, final) through Denver's inspection request system. After all inspections pass, Denver Building & Fire Code closes the permit and the ADU may be occupied.

Code basis

What Denver reviews against

Denver Zoning Code Article 5, Section 5.4 (Accessory Structures and Uses), Denver Building and Fire Code, Colorado Energy Code (IECC adoption), and Colorado HB24-1152 (2024) statewide ADU mandate.

Residential permit page Denver permit portal

If you skip the permit

What can go wrong

Denver Building & Fire Code can issue a Stop Work Order and require full after-the-fact permitting for any unpermitted ADU construction.
An unpermitted ADU cannot be lawfully occupied or rented; it lacks a Certificate of Occupancy.
After-the-fact permitting is significantly more expensive and may require exposing completed work for inspections.
Denver code enforcement can assess daily fines and place liens on the property for ongoing violations.
Title, insurance, and financing complications arise when a property with an unpermitted dwelling unit is refinanced or sold.
Colorado construction law requires contractor licensing; performing permitted work with an unlicensed contractor creates additional legal exposure.

FAQ

Common Denver adu permit questions

Do I need a permit for an ADU in Denver, CO?

Yes. Any ADU — attached or detached — requires a residential building permit from Denver Building & Fire Code with concurrent zoning review by Denver CPD. An ADU is a separate dwelling unit and is not processed as a simple accessory structure.

What is the maximum size for a detached ADU in Denver?

Under Denver Zoning Code 5.4, a detached ADU may not exceed 864 square feet of gross floor area, or 50% of the primary dwelling's gross floor area, whichever is greater (up to the 864 sqft cap). Maximum height is 24 feet.

Does Denver require owner occupancy for an ADU?

No. Denver Zoning Code 5.4 does not require owner occupancy. Colorado HB24-1152 (2024) also prohibits municipalities from requiring owner occupancy as a condition for ADU approval.

Does Denver require additional parking for an ADU?

No. Denver does not require additional off-street parking for an ADU in its urban and suburban residential zones under the current Denver Zoning Code.

What are the setbacks for a detached ADU in Denver?

Under Denver Zoning Code 5.4, a DADU requires a minimum 5-foot setback from the rear lot line and a minimum 5-foot setback from each side lot line. The front setback must meet the standard zone-district requirement.

How long does a Denver ADU permit take?

Standard plan review at Denver CPD and Building & Fire Code typically takes 4–8 weeks. Total time from submittal to permit issuance is commonly 8–20 weeks. Correction rounds, utility coordination, and inspection scheduling all add time.

What does Colorado HB24-1152 mean for Denver ADU owners?

HB24-1152 (signed 2024, effective January 1, 2025) requires all Colorado municipalities to allow ADUs by right in every zone district that permits single-family residential use. It prohibits owner-occupancy requirements and certain other barriers. Denver already allowed ADUs in most residential zones, but the state law now serves as a minimum floor that Denver cannot undercut.

Sources

Official links and freshness

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