Blog ADUs in Denver

Nov. 17, 2021

Painting of missing small housing options by Alfred Twu, with an alteration to focus on ADUs

Denver, let’s talk Accessory Dwelling Units, or ADUs for short.

You might have heard about these smaller and cheaper homes in your back yard. They’re slowly coming to more and more neighborhoods. They’re great. We love them!

What you probably don’t know is that building an ADU is probably legal* where you live - even if it’s not zoned for it. Why?

Blueprint Denver, our city plan

City plans are a roadmap - they don’t tell you what you can do right now, but they do let you know what can happen in the future. Blueprint Denver specifically encourages ADUs in all residential areas in the city. Denver passed Blueprint Denver in 2019 and is the most recent citywide plan, giving it a lot of weight.

Denver’s Zoning Code

The Zoning Code is what tells you what you can do right now. If you build something on your lot and file for a permit but not a rezoning application, that will get called “by-right”, since it lays out your rights on your property. The zoning code and the city plans get out of sync though. The plan says “These buildings would be great!” and the zoning code says “nope”. How do we reconcile those? Rezoning.

Chapter 12 - Rezoning

This is some nitty-gritty. Sorry for getting technical, but these technical details are what unlocks ADUs everywhere. Bear with us.

Any resident, or city council, and seek to change what you can do on your lot. There’s a process for it, and that process is called rezoning. The city lays out the steps here:

Chapter 12 of the Denver Zoning Code creates the rezoning process. For now, we can skip to the five criteria listed in Sections and for whether a lot should be rezoned. This is the rubric that city staff, then planning board, then the Land Use and Transportation Infrastructure committee, and then finally city council must use when evaluating a rezoning application. That’s a lot of steps, but it’s not as scary as it seems.

A rezoning application is heard at city council, but it’s not like other matters that city council decides upon. A rezoning application isn’t a political decision, it’s a quasi-judicial one. That means that city council members are acting like judges, evaluating whether city staff and planning board followed the rules. If they did, great! City council will follow their suggestions. If city council thinks someone messed up along the way, they’ll say that.

(Wanna know what a quasi-judicial decision is in more detail? Check out page 41 here: Colorado Municipal Leage presentation on land use )

What does this have to do with ADUs?

The five rezoning criteria basically have the same facts and reasoning for any rezoning application for an ADU in Denver. Let’s walk through them.


  1. Consistency with Adopted Plans
    Newer plans will tend to supersede older plans. Blueprint Denver is the newest citywide plan we’ve got. They also support ADUs in all residential neighborhoods in Denver. Some parts of the city (like East Denver and East Central Denver) have more recent and more specific plans than Blueprint Denver, but they all recommend ADU’s for even the lowest-density areas.
  2. Uniformity of District Regulations and Restrictions
    This one is kind of a technical point, but there’s ADU vs non-ADU flavors of what a property can be zoned for. Changing from a non-ADU flavor to an ADU flavor satisfies this.
  3. Public Health, Safety and General Welfare
    Yep. Blueprint Denver supports ADU's in all residential zones, and Blueprint Denver lays out what supports the health, safety, and general welfare of Denver, so your ADU probably qualifies here.

  1. Justifying Circumstances
    “Since the date of the approval of the existing Zone District, there has been a change to such a degree that the proposed rezoning is in the public interest. Such change may include: ...A City adopted plan...”
    The city of Denver adopted Blueprint Denver in 2019. The Denver zoning code as it applies to ADUs was last updated in 2018. For the foreseeable future, that counts.
  2. Consistency with Neighborhood Context Description, Zone District Purpose and Intent Statements
    Blueprint Denver says ADUs are encouraged in all residential areas. Checkmate.

Why isn’t this happening everywhere then, if it’s basically legal?

A rezoning application is expensive. It’s time-consuming. You’ll probably need a contractor who knows the rezoning process. You might have to fight with your neighbors if they don’t understand the process, and they almost certainly don’t. Maybe your specific lot and the building forms allowed still won’t make it possible. There’s a small chance a rezoning application for an ADU will still fail, because politicians are human. All of those things make it harder to build an ADU.

But, if you want to build an ADU, the balance of evidence is on your side that you’ll be able to build one**.

We hit the books and found that city council approved almost every application for an ADU, regardless of what the neighbors think. As an example, this ADU was strongly opposed by nearby neighbors and the neighborhood organization. City council approved it unanimously.

You can check our math by looking through the City Council records if you don’t believe us:


Can’t city council just make it legal everywhere, since you’re telling me it’s basically legal?

It’d be great if they did! City council’s decision to apply for a neighborhood-wide or city-wide rezoning takes political courage. They might decide it isn’t worth their time to work on it without a lot of outreach. City council’s inaction isn’t blocking you from rezoning yourself - it’s just making missing housing more expensive.

Why are we talking about this?

Because Denver is not full.

Because Denver is in a housing crisis.

Because ADUs shouldn’t be limited to only those who know how to navigate this arcane process.

Because you deserve to know that you’ll probably succeed if you want to build an ADU***.

So, what do I do now?

If you want to build an ADU, start talking to a builder! Spread the word.

*We’re not your lawyer, this isn’t legal advice

**Technically, the zoning code says that city council may approve an application if it meets the criteria, not shall. They don’t necessarily have to approve it - if you’re building an ADU just to record screams for your homemade horror film, and you don’t plan on having any soundproofing, that’s just rude and would probably get denied. But housing, sure.

***We’re still not your lawyer. But thanks for sticking with us through this whole post.