I also looked at what my future earnings potential with my corporate job plus the real estate I owned then my earnings potential if I solely focused on real estate.

If we isolate each additional bedroom past 4 and look at the bedroom ROI in a vacuum that's a 96% return, or 2,000 % Cash on Cash (house hacking with 5% down) for each additional bedroom past 4 you can find / create in a single family home.

If I were a resident I would like the somewhat isolated location of the town but it seems far from many major employers, that is unless your tenant works at one of the many warehouses nearby. 

Jobs are scarce and people are isolated and live in very very bad conditions = no (obvious) growth potential. 

and what about you, are you isolating yourself? 

I find that very wasteful.On the other hand, I can isolate that top $10K off of my mortgage and because I'm putting all of my income toward it (and not paying interest on the rest of the mortgage while I do it) it costs me around $1000 in interest and takes less than a year.

Thereby sidestepping the requirements to bring it up to current code while fulfilling the original problem which is the sound isolation from the adjoining unit. 

@Joseph LewisThe problem with Detroit is that they were a manufacturing city and the manufacturing left.At that time instead of local government finding a solution, a combination of corruption and racial hostility isolated Detroit from almost any new investment.The result is the impossibility of financing government operation in a city where infrastructure is built for 2,000,000 but where only 625,000 reside.

I solely own them because I know there was a market for both in the area.

Account ClosedCan you isolate the water to just that unit?