Cash flow vs ROI vs break even point

[Jon Moore]

Hi everyone. Just curious how you guys are analyzing your rental property investments, specifically with regard to investing in existing properties in the form of additions and other improvements that increase monthly cash flow.

Do you focus more on monthly cash flow? ROI? Or break even point?

For example, I finished some attic space at one of my rentals a few years ago and increased rent from 950 to 1600, which I thought was cool. It cost me about 25-30k with me doing most of the work.

Currently, I'm adding a full second story that im very confident will increase my monthly cash flow from $2250 to $3750 but will probably end up costing me close to 80k by the time I'm done. Do those numbers still work do you think? Additional info - this project was spurred on by a terrible roof and even more terrible structural support under said roof so that stuff needed to be done anyway.