These properties don't really have negative cash flow, except when evaluating based on the asking price.

@Stevie Nosekabel is your company based in Ohio or based here in Texas?   

Also using a percentage of revenue is inherently flawed, I assure you that whoever you have doing your maintenance or improvements will not base their pricing on what you receive in rent.That said I understand that some we need to have some convenient way of budgeting for these expenses.

The R20 zoning does have it's limitations but an ADU of less than 800 square feet with off street parking is allowed and the permitting process is generally quicker because of the nature of the building.

The real question is how much interest rate and how many points based on your specific profile, which will become clear when you provide all your information to a mortgage lender? 

@Zachery Hitchcox & @James Thomas:Although there's a small group of us here on BP who are based in Japan, I do not recall seeing this topic before. 

Making $25k over summer concerns me based on the estimated value of your home.

These loan don't let you close in your company name because they are based on you.Portfolio - I'll define these loans as loans that come from the bank's own "portfolio" of money.

You may want to see if you can claim real estate professional status now or sometime in the future based on your participation within real estate of being a landlord in addition to being an agent.You may want to have your past couple of returns looked at for review to see if they were done correctly.

The XIRR formula is much more flexible and is based on the dates of the cash flows for the project.