We recently just put a dehumidifier down there and are looking to dry lock the basement 

Even if you do preventative things it won't keep it dry.

It's been great in years past, however, due to saturation and stricter registration/compliance requirements, bookings have really dried up here and many are converting to longer-term rentals. 

I can about promise you Statefarm will leave you high and dry!

In my situation, a professional clean up crew repaired everything and also didn't find any mold inside of walls before starting the cleanup and new flooring and dry walls were installed and it was over ten years ago.

Seems cut and dry that with limited exceptions JADU can require owner occupancy. 

Many agents will place the first applicant with the necessary funds, take their commission and leave you high & dry with a bad tenant.YOU SHOULD DO YOUR OWN SCREENINGS! 

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?

The combination of hot long summers (soil dries out) and lots of moisture in winter and spring (saturates the soil) causes the ground to constantly expand and contract.Out of state investors get freaked out by foundation issues but being that its such a normal occurrence, you have a plethora of foundation companies that know how to fix them with relative ease. 

The kitchen is what's sold me in my first house and it'd a great lay out in my current house.My next house I'll be a bit more specific - bigger deeper sinks, pasta faucet even if I only use it once a yesr for a big jug of summer iced tea lol and a dishwasher, walk in pantry are on my check list.I feel other amenities like skylights or big windows, cellars for dry storage would be cool too but I'm not really a big baker or canner lol.Now it's got me thinking - imagine a hidden island?