@Nicholas Sambrick In addition to those mentioned, I'd add The Real Estate Rehab Investibing Bible by Paul Esajian, and Real Estate Wholesaling Bible by Than Merrill (even if you aren't planning to wholesale).Also, @brandonturner published  "The Best Real Estate Books for Your Investing Business " on BP which might be helpful.I find audio books work best for me on the way to and from work.

Remember that when you do a refi, you are usually taking on additional debt.

@Joe Splitrock, good info, I had not thought about additional income from other sources.

Additionally may will fail for a variety of different reasons.

You are missing the fact that it needs to be zoned for an additional unit. 

They could put an addition on doubling the size of the house, and if every other house in the neighborhood is at $500k, it still wouldnt raise the value $100k.

We are planning to hold the property and add it to our management portfolio. 

The property consists of 4 structures - 2 duplexes, an SFR and 2 car garage, and has 3/4 of acre.Here is the link to my analysis using the BP calc assuming a $455,000 purchase price and below is quick summary.https://www.biggerpockets.com/calculators/shared/260799/874435c9-b77f-4f96-a3de-90be11c4cbbaThe asking price is $475,000, Assumed purchase $455,000.I've assumed $30,000 in repairs as a place holder (TBD)Current Rents total - $4,700 + an additional $75 in income from laundry machines _ According to listing broker.Taxes are $5,868 (verified)Insurance $4,500When factoring in other expenses - landscape maintenance, water, elec, vacancy, repairs, cap ex and PM I end up with $610 in cash flow.

We also bought out own personal property in June of 2017 which we have updated and finished the basement on to add an additional bedroom, bathroom, and family room.

If your primary is 600 sqft, I am not certain an 864 sqft additional structure would qualify as an ADU.