I would focus on improving your credit first.

@Michael NealHi MichaelRead your profile, nice job man!

The refinance is going to leave us with about $20k left over, after the improvements.

I'm a fan of buying equity and then forcing more equity through improvements. 

Feel free to join our NYC RE meetup, found under my profile. 

If truly all it needs is a new roof to be complete and ready to sell then a few ideas off the top of my head could be:1)  Borrow the money from friends or family to replace the roof2)  Put the cost of the roof on a no/low interest credit card and pay it off as soon as the house sells3)  Go through a home improvement store (like Home Depot) that offers financing for larger projects like roof replacement4)  Don't replace the roof and just lower your sales price or offer the buyers a credit to fix it themselves after closing

Being in the home improvement business as a contractor since 1992 I have helped many investors and homeowners in my area in all phases of home improvement.

Since you would have more units, you would have more scale on depreciation of appliances and improvements like a parking lot or security lighting that you may not have on a SFR.

Yuck, unless he just wants to help his son and doesn't care about his real return.Your profile doesn't indicate any experience, Kevin, which makes this a relatively high-risk real estate loan.

Also is area improving.