You want the worst one in the best neighborhood!

My post was initially just to understand my options in the event of a worst case scenario however I want to make sure I have buyers first before I even start thinking about finding sellers.

Worst cast scenario you sell it cheap  for $3.5M and make some quick $$I would get a 3rd contractor out to take a look and see which one is to be believed.

You refi the property for $800k (worst case?)

Worst case scenario is the lender will be upset, but they have not legal recourse because of the exempted status of the transfer (unless you violate other terms of their note.) 

Its 170,000 and worst case each door would rent for 400 and the adverage in the area is 525.

As the inspector what he thinks it will cost and ask for worst case scenario.

The state protects the public, not licensees.But that’s not nearly the worst part because if the seller sues you and they win an award you can’t or won’t pay, they still can recover their entire award from the state’s “recovery fund”.  

If they are "reasonable", it may be difficult to justify any charges for repair in court (worst-case scenario).

On the worst case scenario you'll need to do exterior water proofing which will run you $100-$125 per foot.