If the foundation of a home needs work, how would I estimate my repair cost on a home that has 1800 square feet ?

If the ADU actually costs you $500K, it's barely worth it in terms of cashflow.

Up (2 bed/ 1 bath)  and down (1 bed/1 bath) duplex located in a B-/C+ neighborhood in CincinnatiPurchase price: 147,500Estimated cost of rehab: 38,050ARV 215,000Rent-income: 2,045/monthCOC ROI: 7.75%My hesitations:1. 

It ultimately cost us almost $100,000.

Just another cost that a lender has to consider on a PERFORMING asset.

After assessing the cost of remodeling, and either renting or selling the property weighed against the advantages of selling as is to a builder it seems to make more sense to sell it as is. 

If you focus too much on cash flow right now, from abroad, you are going to get more maintenance and more costs with it.

The seller is willing to finance 50% of the cost and defer payments for 5 years.

I would get out of that note as soon as possible to avoid any further charges, 10% in extension cost is the most I've seen recently.

Its just a cost of doing business .