You need to define your question better. You are asking about multifamily 3, 4, or 5 plex. 3 & 4 fall under residential financing, which means that you can actually buy them with 3.5% downpayment if you qualify for FHA owner occ financing, or you can buy them with 20% conventional financing as an investor, again if you have full-doc app.
5 and more units fall under commercial financing, and you will need at least 25-30% down depending on many factors that your lender will consider, unless you know how to be creative with seller participation, mez financing, bring in a money partner or equity share agreement, os something along those lines.
Feb 1, 2011