I borrowed $110K from a private lender for the purchase and self funded the repair of the offices. 3 months later, I rented 6,000 sq.ft. of office space to a corporation for $21,000/month + utilities for 5 years with another 5 year option.

The lender is the one who sets this up as they are the ones who typically pay since its them who is to provide this as well as keep track of the loan, but only be a borrower if they use a servicer.

The bank then understands that their borrower no longer owns the property and calls the note due.

The borrower defaulted and was a few months behind.

One of your risks is that you get the money first and then get into bad deals because you think you have a need to deploy the money you borrowed. 

Can you borrow 80% for 30 yrs on the investments you named?

Remember that the leveraged purchases are not going to add significant cash flow immediately and borrowing against existing properties will also reduce their cash flow.

In the Netherlands, for example, banks typically offer refinancing options with a Loan to Value (LTV) of up to 80% in some cases, depending on the property and the borrower’s financial history.

It drives me crazy when I hear these stories preventive maintenance is what should be practiced and discussing all avenues of the deal and the borrowers docs in advance.   

What rate, term and amount borrowed did you get for the ADU build and what was the cost?