If I'm getting this right, it's more on the assumption of a period or window of days rather than a specific amount of days rented.  

My husband is a doctor, which creates the assumption we have large amounts of wealth and can potentially put us at a higher risk for lawsuits.  

With a house in that price range, I will make an assumption on the square footage, but guess that a new roof will cost 10K. 

Aloha @Melissa UmedaJust a few thoughts on your original post (plus a few assumptions):-I think $92 a month for the vacancy rate is a little high.  

My assumption is that the rates go up if you use the improvement loan?

Now doing some basic math with a few assumptions, those assumptions to keep my example simple, each spot is rented only once in the morning, and only 250 times a year to reflect federal holidays...$5.00 x 25 cars x 250 federal holidays = 31250now I'm not sure of how much of a percentage to calculate for vacancy or expenses so I'm going to just guess at numbers and hopefully all of you can help me with the reality of these numbers.vacancy 10% = 3125, expenses 10% = 3125 so in my example31250-3125-3125 = 25000now in many areas there is a tax levied on parking lots, I do not see one in Tacoma where I am looking other then B&O taxand then there can be sale tax in Washington on parking based depending on the length of term and if you have assigned parking.So in my mock example there is a sales tax of 10% or 2500 for a total remaining profit of 225002A.

You'd then want to "lay eyes" on the property to confirm your assumptions about ARV and repairs.The process is similar for buy-and-hold deals, but you'll also need to know comparable rents (use Zillow and Rentometer.com), estimated taxes (get online from public records), and estimated insurance (talk to an insurance agent).

Or would you also make assumptions for vacancy and CapEx?

I'm sorry to say this, but what you did is definitely an overkill, even considering you guys are physicians (just making an assumption that you make good money and have some assets.) 

I chose NOT to do an assumption because I don't want the mortgage to affect my credit and debt to income ratio.