The builder dried with fans and made sure there was no moisture.

Im building in an area where new con has avg 14 DOM - specs that sell before the slab is dry,  Wilmington Nc area (beaches) where it then buyer eventually wants some things changed.

I had Rental Duplexes and some Houses in South Tampa for 30 years and the kinds of damage and rot you are talking about with the 100 year old side of the Duplex need to be shown to Code Enforcement in case they would consider it a Tear Down structure.

Around here the auctions are dried up. 

These are large once-expensive homes that are now rotting on parcels of land that nobody wants.

The first 5 times will be painful and frustrating - watch one of Brandon's or David G's videos on how to run the numbers - you'll become quick after a few dry runs.Just make sure you underwrite the deals against your Goals (ROI %, Cashflow $, potential longterm appreciation, etc), and run the numbers as if you're NOT in the property. 

I say that because the primer to cover the water stain may have to have your renters And their pets out of the unit for so many hours while they do it and then it dries because it may gas off.

In CA, landlords provide microwave, ove, dish-washer, washing/drying machine and gardening.Let me know what you think.

And if have to decide between doing nothing and letting cash sit and rot away to inflation, buying a cash-flow maintenance time-bomb, or an INVESTMENT into a good appreciating property/market, it's a no brainer APPRECIAITON every-time.   

As I am set up now, all rent proceeds go into my checkbook LLC account and rot there until I accumulate some and put it to use elsewhere.