Calculating Cash Flow - Am I doing this right?

[Katie McDonald]

Hello Everyone!  This is my first post to the BiggerPockets forum.

My boyfriend and I have been looking into investing is a real estate property. We've read many books, done our own research, listened to podcasts, etc. in order to prepare for this next adventure. I have been practicing using the four corners worksheet to calculate income, expenses, cash flow, and ROI for different houses to get a feel for what is going to be cash flow positive.

So, the real reason I'm here is because one of our coworkers is selling his townhome and came to us first to see if we would like to use it as a rental property.  It's a 4 bed, 1.5 bath, 1400 square foot townhome.  It needs a new roof, new HVAC, new appliances, and new flooring on the second floor.  He is willing to offer us the home for $135,000.  I have entered the numbers into the worksheet, but I wanted to get another opinion of whether I'm doing it right.

Total rent per month: $1300

Purchase price: $135,000

For expenses I have:

Mortgage payment: $648

Taxes: $146/mo

Insurance: $84/mo

Vacancy (5%): $65

Repairs: $100

CapEx (10%): $130

Property Management: $100

Adding all this up, I've calculated a monthly cash flow of $27.

I'm stuck on calculating the rehab cost.  Since we need big stuff like a new roof and HVAC I'm sure it's close to $30,000.  Any additional help would be much appreciated!  

Thanks in advance.