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?

You could even buy a property and convert the garage with the difference (although you don't get dollar for dollar value from an appraisal perspective). 

I have one investment property (primary home converted to a rental, my first tenant will move in mid-April) and I have been getting mixed opinions on what is best for someone just starting.

My guess is we start inching up then bouncing around equilibrium.

I have friends in CA who converted their two-car garage into an apartment and used it for additional income.

I preferred a duplex, but the market was too hot for me to compete so I bought a big house and converted it to multiple units so I can live in one and rent the rest.

I preferred a duplex, but the market was too hot for me to compete so I bought a big house and converted it to multiple units so I can live in one and rent the rest.