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Denver, CO Accessory Structures: ADU Rules (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified August 2026

ADU rules in Denver, CO, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

ADUs allowed: One per primary dwelling unit
Non-SU-district lots: Detached duplex/row/town house only
SU-district owner rule: Owner must occupy primary home
Prohibited structures: Mobile homes, RVs, trailers
Max fine: $999 per day violating

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in Colorado under recent ADU streamlining laws. The Denver, CO rules below cover local size, height, and setback requirements.

Summary

Denver allows one accessory dwelling unit per primary house, duplex, or multi-unit building in every zone district, but a permit applicant in a single-unit district must already occupy the primary home as their residence.

One Accessory Dwelling Unit use is permitted as accessory to each Primary Dwelling Unit containing a primary Single Unit Dwelling, Two Unit Dwelling, or Multi-Unit Dwelling use on a Zone Lot according to the requirements in this Section 11.8.2. ... At the time a permit application is submitted for an Accessory Dwelling Unit use accessory to an existing Primary Dwelling Unit, at least one owner of the existing Primary Dwelling Unit shall occupy the existing Primary Dwelling Unit as the owner's primary residence.

View official code

Full Breakdown

The Denver Zoning Code permits one Accessory Dwelling Unit (ADU) as accessory to each Single Unit, Two Unit, or Multi-Unit Dwelling on a zone lot, with ADUs on Two Unit or Multi-Unit lots required to sit in a detached structure built as a duplex, row house, or town house. Mobile homes, RVs, and trailers cannot serve as an ADU, and the unit gets only one kitchen. In single-unit (SU) zone districts, at least one owner of the primary dwelling must occupy it as a primary residence when the ADU permit application is filed, unless the owner is the Denver Housing Authority or a structure is being built simultaneously with a new primary home.

Violations & Fines

Building or operating a noncompliant ADU is a Zoning Code violation; the city can suspend or revoke the zoning permit, and unresolved Code violations carry a fine up to $999 per offense, with each day of continued violation a separate offense.

Frequently Asked Questions

Does the homeowner have to live in the house to add an ADU in Denver?

In single-unit zone districts, yes: at least one owner must occupy the primary home when the ADU permit application is filed, unless it's a Denver Housing Authority property or built simultaneously with the primary house.

Can I put a mobile home or RV in my backyard as an ADU in Denver?

No. The Denver Zoning Code specifically bars mobile homes, recreational vehicles, and trailers from being used as Accessory Dwelling Units.

Sources & Official References

[1]Denver Zoning Code, Article 11 — Use Limitations (Community Planning and Development)

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All Denver rules

How Denver compares: Easiest Cities to Build an ADU·Compare Denver to another location·View the Colorado accessory structures overview

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