We already paid them a pretty sizeable entry fee ($30k) to cover some of their equity and debt in another project..Your title report should have alerted you to the issue.The payoff the escrow company got from the lender should have alerted you to the problem.Your interview of the seller before you bought the house, should have alerted you to the problem.You calculations on the numbers should have alerted you to the problem.Check, cross check and check again.

Then you can pretty easily calculate what the holding costs of that home will be and when you'll have to replace those systems.

Here's a bit more in detail about how rates are calculated for DSCR loans:1.

Calculating these losses involves documenting the fair market value of the property before and after the disaster, adjusted for any insurance or other reimbursements.

I appreciate that, and you're right, any back-of-the-envelope calculation suggests that much of the wealth comes from the equity accumulation, even in the earlier stages of the amortization schedule.

Do the calculation to see if there is enough profit in the deal for you after splitting with your buddy.

In hindsight I can see all the mistakes I made but...pura vida.I do my proformas and try to calculate returns but I don't measure the value of investments purely on these terms like some others who've responded to you.

@Zach Howard the basics of the Rental Purchase Calculator is easy to understand and replicate.Google and you can find many similar spreadsheets for free.

I simply negotiate that WITH seller and get sellers approval, in which seller would be a signor to it all because THERE AWARE and nothing is shady under the table stuff and the C4D has all this calculated into it. 

Understand the fees involved and calculate the total cost for an entire year of management so you can compare the different managers.