That would put you at a huge risk if it were ever to be inspected by the city as they would likely force you to de-convert that unit. 

So you did not convert those room into rental until 2024?

Convert the garage and do it right, not just ping pong and a pool table.

I Bought a dental practice with my wife 2 years ago, so once we are no longer poor from that, plan is to convert 3rd property into a STR.

By eliminating your mortgage, you converted LONG TERM debt into SHORT TERM debt.

Many of the STR communities are strictly for STR only, and cant be converted into LTR. specially in the Davenport areaI am a bit concerned about the quality of the schools in the area as I know that affects families staying long term in an area. 

I converted this into a 2 bedroom via Zillow.

All of the meetings that I see about ADUs are sponsored by builders who want to sell their ADUs.Are there others who want to build their own or want to share their experiences about building ADUs / converting outbuilding / navigating codes in Portland that DO NOT involve hiring one of these tiny house start-up companies?

With the 2019 ADU law, we are considering converting the duplex to a single family home plus ADU, so that we can build a DADU in the ample backyard.

I am a first time real estate investor looking the following property : https://www.redfin.com/OR/Forest-Grove/2418-Cedar-Cir-97116/...its a pretty large duplex in Forest Grove OR,  the trick is though, its on a lot zoned for a 4 plex so I am lookinginto house hacking, converting into a triplex, then living in one unit while renting out the remaining two unitsThe left garage has been converted to living space, with a living room, half bath, a laundry room with a sink and some counters/cupboards and a bedroom, it is a part of what was an existing 3bd unitIf I were to acquire the asset, I would first attempt to convert that space into its own unit The line items as I see (be in mind, I am totally new to this) would be to >put up dry wall where the door to the rest of the house is,>add a shower to the half bathroom >install a water heater in the adjacent 3bd unit> install a kitchen in the laundry room, (stove , oven , sink, counter space)>add a shower to the half bath Assuming I can convert it to a 3plex, I could at-least cash flow on my investment after I leave My plan would be to put minimum down payment of 3.5% (FHA loan) that way I can have a decent amount of capital free to do the renovationsThe only concern is when I crunch the numbers to get my ROI, I have no idea how much its going to cost to convert the additional living space to a third unitAny experienced investors here know how I can estimate this before I try to make an offer?