Denver Duplex in TU-C - Can you have an ADU in basement?

[Santiago Arteaga]

Hi! I have a duplex in U-TU-C zoning. I have a basement with a partial kitchen and would like to give it an independent access. According to code this turns that space into a "Complete and independent dwelling unit" CIDU (great City document explaining that here). What I cant figure out from the code and after spending hours of research:

is whether in a U-TU-C, in a Duplex unit, you can legally have a CIDU? (that overall structure, would have the neighboring duplex, my own main duplex area plus the second dwelling unit in my basement)

Anyone who can guide me?

I think the key lies on this text from the above cited city doc, but I am not smart enough to interpret it:

Code Compliance Consequences of a Second Complete and Independent Dwelling Unit Finding:
If a second CIDU is found:
1. The Denver zoning codes will apply to determine whether a second Dwelling Unit is permitted in
the subject zone district. A second Dwelling Unit is allowed in the following scenarios:
a. In a zone district that allows the Accessory Dwelling Unit (ADU) use as accessory to a
primary single unit dwelling use (e.g., U-SU-C1 or R-MU-20), the second CIDU would be
considered an attached ADU zoning use, and must be permitted as such.
b. In a zone district that allows Two-Unit Dwelling use (e.g., E-TU-B or R-2), the second CIDU
would be considered part of a Two-Unit Dwelling use of the entire structure, and must be
permitted as such.
2. Where a second Dwelling Unit is allowed by zoning, the IRC shall apply to require, among other
things, any necessary fire safety separation between the Primary Dwelling Unit and the second
CIDU.

[Chris Freeburg]

@Santiago Arteaga The key is in the Exception to a Second Complete and Independent Dwelling Unit Finding: If there is a "A Non-separated, Continuous, and Open Access exists between what would otherwise be
deemed a second CIDU and the living room or Kitchen of the Primary Dwelling Unit" then the (otherwise) second CIDU would not be considered an ADU.

Translation: As long as there is a hallway greater than 48" that cannot be closed, then the whole thing is considered one dwelling unit. Basically, the city wants your side of the duplex to be inhabited by just you and your family (one family unit), so it's okay to add independent access to the basement as long as long as that isn't basically creating a front door for another separate unit. 

Logic: The city wants to allow kitchens downstairs for in-laws, adult kids, etc. because they're considered part of the family and would probably move up/down between living spaces. Maybe you wanted a souped up wet bar for hosting Super Bowl parties and movie nights where you could heat up your pizza pocket bites in the basement without going upstairs to the kitchen... They also want to allow egress so that people can escape said movie theater or a basement bedroom in case of a fire. The city wants safety and enjoyability of living spaces, but not people renting out part of their one unit structure to another family unit (b/c of the effect on density, parking, etc).

Application:

-If your unit already has a lock-out basement (door that separates the basement from the upstairs) and a bedroom/bathroom/kitchen (or even a partial kitchen, which would not have a stove or 220V/gas. A partial kitchen might just have that microwave for hot pockets!), you can't add a separate entrance

-If you have a lock-out basement, a microwave downstairs for the theater room and a bathroom, but no bedroom, you could create independent access to allow guests to come in. It's not a separate dwelling unit, because they can't sleep there.

-It's really common for builders to provide a locked out basement, get the plans and construction certified, and then add in a stove at the very end. Not to code, not what the city wants, but it happens.

So, if you already have a full/partial kitchen (see definition in the document), bedroom, bathroom, and can close off the space, any independent egress you add would not be to code and would not be legal.

Beyond that, it would take neighbors reporting "So-and-So has a lot of cars parked outside their house and multiple young couples living there; smells fishy" to the city for something to happen. I haven't heard reports of this like I have of Denver cracking down on STRs, but I'm not sure I would want to push my luck. There are better ways of making money that are legal, not headaches, and don't keep me up at night. Alternative: Maybe you do STR (while it is your primary residence) and just know that your guests might use the same entrance/exit as you? I bet you'll make a killing! It might seem inconvenient at first, but money has a way of smoothing over rough edges...