(Excluding insurance and taxes)+10% property management +10% management costs+10% capital expenditures So that in general, I need to add an additional 30% to the note + insurance + taxes in order to be very safe in a cash flow cushion...Is this too conservative, 30% extra on top sounds like a lot.

Hi BP,I have a situation and wanted to know if my thinking is right and if this is a good deal:Purchase price 105KARV - 150KRehab Cost - 32.5KClosing Cost / Fees / Buffer - 2.5KMonthly rental - $1200Monthly expenditures - $900 Cash Flow $300This is only a 2.5% return if I was calculating on the 140K I put in, but if I refinance and pull out 70% of the ARV, I will get back 105K resulting in me putting in only putting in 35K for this house.

And you may have more capital expenditure items and furnishing costs.

Sure, duplexes come with a higher price tag, but your remaining mortgage payment after you apply the other unit's rent should be less than your mortgage payment on your single family; thereby leaving more, not less, cash for capital expenditures (i.e. major issues).

We are putting into a savings account a portion of the rents each month for capital expenditures.  

That's one way to immediately increase your return if it fits in your market.Also, have you thought about capital expenditures?

I did not see a budget for Capital Expenditures and Property Management.

Plug in your own numbers for cash-flow and cap-ex expenditures to see if you think it can self-support.

Multiple rent income helps cover the bills even if one is vacant, capital expenditures like a roof are covering more than 1 unit (rather than replacing 4 roofs, you have only 1), POTENTIALLY more cash flow per month.  

@ChristopherPhillips and @JeffB. are correct in that these capital expenditures are adjustments to your basis for depreciation if done before placed in service date.