IDK standard construction cost in Mass. but if this were is Milwaukee just based on #units and sqft my napkin math would say about $2.6 to $3.1MM for the standard interior of the units.

The goal is to pay out my silent partner via sale or cash out refinance in 5 to years.I'm a bit at a loss in terms of how to calculate the math so that the split is properly accounted for upon exit of the silent partner but that we also accurately take into consideration the ongoing payments of income.

Its all math.

You should not be using someone else's prices (or Kukun's algorithm), you should be using your own prices from your local contractors and using the specific material selections you picked for your project.Here's an example of how bad some of the data is in Kukun and why it's not practical for investors that are wanting to create accurate estimates for their projects:I just added "Exterior Doors" to my project, and I was told that 4 single doors and 1 double door is $59,352 in Kansas City, MO which is 20x what I would actually pay as an investor.I believe the above was a bug, but nonetheless there was no way for me to fix this issue or understand why or how it was calculating this value.In summary, you don't need a fancy algorithm to tell you what something costs, you just need to know basic math and have a general understanding of how much materials cost and what contractors charge for specific repairs.For example, if I have 5 exterior doors I need replaced (4 single entry doors, 1 french patio door) this is how I would estimate the costs:- Single exterior doors labor 4 x $250/each = $1,000- Single door material 4 x $300/each = $1,200- French patio door labor 1 x $400/each = $400- French patio door material 1 x $750/each = $750Total = $3,350Add 25% profit for your contractor and the quote should be around $5k for 5 doors.The hard part is finding out what your contractors charge, after that it's just basic math that you can do in a spreadsheet.

Which I think is not bad for someone starting off, y the time the house is on the market I will have done the homework on the next investment.

For the math gurus, how would you calculate the ROI on this deal?

I'll do more homework on the numbers, especially considering the potential high cost for utilities set up which was not in my original calculations. 

As an accountant it throws my math out, but I am guessing there are deals out there that will fit it.

Even if someone recommends an area for you to select, you still have to go and do your homework.

Tons of threads on it and if I remember right once the math actually comes out it's not really this different good or bad.Even if we were to say it works...