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ADU's are about to get a lot easier!

Every City has different rules and regulations for Accessory Dwelling Units, or ADU's for short.

A recent Colorado Senate Bill 23-213 (SB23-213) included new rules that would lift many of the limits that local jurisdictions placed on ADUs. One proposed change allowed ADUs for any property that is zoned for Single Family in an effort to expand housing options across the state.

While it's still in legislation, it's a clear indication that ADU's will get easier in the future. Some Cities in Colorado have already taken their own steps to revise ADU Rules, the two we will focus on are Denver and Boulder.


City of Denver

Denver is now working towards increasing the amount of ADUs by making recommendations to for changes to the Blueprint Denver Program.

Blueprint Denver is a city-wide land use and transportation plan that provides a strategy to enhance quality of life in Denver by promoting and enhancing the relationships between Communities and Transportation.

These recommendations come from Community feedback and include the following:

Increase in Height

New rules would allow Detached ADU's to have 2 Stories, where currently they are restricted 1 1/2 Stories. The Bulk Plane measurement limit is increased for narrow lots, which allows for taller structures near Side Yard Lot Line.

Setback Adjustments

Decks and Balconies

Size Increases

Where Allowed


City of Boulder

Boulder passed Ordinance 8571 in May, which removed many of the restrictions for an ADU, with the changes coming into effect September 1st.

The biggest change (in my opinion) is removing the separate ADU Zoning Review, which was an additional step prior to the Building Permit to determine if an ADU is allowed. Now, you can go straight to Building Permit with no separate approval required, saving time and money for Owners. Additional changes include:

Changes to Floor Area Definition

Removed the current stipulation that the Floor Area of an ADU shall include the egress path, such exterior stairs, walkways, interior hallways or stairs.

This meant that if you had a 500 SF Upper Floor ADU and 70 SF of Exterior Stairs, your total ADU Area would be 570 SF.

Saturation Limit

Size Increases


Boulder County

Following the 2021 Marshall Fire, Boulder County adopted Article 19 which provided regulations to those directly affected by the Marshall Fire. While it mainly covered the reconstruction process, it also included some new ADU rules.



It's likely we will see other jurisdictions add rules or language to their Code in regards to Accessory Dwelling Units. Many locations are asking for resident feedback as they look to update their policies, such as Westminster and Denver.

Feel free to message us if you want to learn more about an ADU for you!

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