Renting parts of the house separately and legally

[Jennifer Smith]

I have a three-bedroom, two-bath house. One bed and one bath are accessible through a separate entrance. I am going to be building an ADU in my backyard soon.

It is my understanding that it’s likely to eventually be legal to have two ADUs on the same property in Portland (a basement and a detached, for example) but that it’s not legal now.

Is it possible for me to legally rent my basement unit separately from the upstairs of the house, without running afoul of anything legally? I plan on refinancing the home as a rental, with signed leases for the upstairs, the downstairs, and the ADU, as long as that's legal.

Or would I need to legally turn the basement into an ADU eventually to have that be legal?