He wants to flip after work completed. 3 to 6 month estimated rehab. 

You must be able to know what works for the investor and also works for you . so make sure you are factoring enough cushion for negotiations .3# Estimates Be able to access the approximate renovation cost for your investors . complete a spreadsheet that will help you calculate cost .

Having to completely redo the roof on a friend's addition that's only ten years old because they did this.

Also have some verbiage to ensure subs are paid after work is completed.

You would have a tenant in charge of their own unit, which is a recipe for disaster, and they may completely suck at managing the neighboring unit.

The other side of the coin is that we have been considering then, paying the CC bill with the HELOC and of course after selling, paying both back off completely. 

We did a complete renovation, literally flipping the house (shifting living room to bedroom side of the house and vice-versa. 

I'm primarily interested in 2-4 unit multi-families.  

I'm an investor who typically is very logical, and my opening question is completely illogical. 

We all want to be completely prepared before going in.