Yeah you're just on a standard net lease.

Find a JV partner, or if it's short term flip try to find a flat fee lender with a 90 day payback time frame where your fee will be less than standard interest

I understand that is apartment is not to standard and will be that way every time it rains hard until we fix the issue.

I am trying to find the standardization for what a lender should be properly using to calculate net income and thus freeing up DTI.

I don't know if there's really a standard, but you might think of it as a balance.

@Deborah Repaskey Buying a house that is 70 years old is getting better every year, one of the biggest issues with older homes tends to be knob and tube wiring or plumbing that isn't copper, both of these really started to be changed to modern standards starting in the 50s so that decade can sometimes be a mixed bag but those are going to be your primary concern unless someone hasn't replaced a major system like a roof in 70 years. 

@Darren James  Either do a standard rental or sell on owner financing (Note/DoT). 

Looking to do owner finance, is there a standard for down payment 10% 20% 0%?

I am willing to make the investment to minimize future water damage issues whether coming from laundry room or overflow bath or internal pipe leak. 

ALSO" (i) Multiple accessory dwelling units within the portions of existing multifamily dwelling structures that are not used as livable space, including, but not limited to, storage rooms, boiler rooms, passageways, attics, basements, or garages, if each unit complies with state building standards for dwellings.