This is usually too technical to mention to borrowers so typically I tell borrowers that the gross rental income from all units must be .90% of the sales price or higher in order for FHA to finance the 3-4 unit property. 

Scenario A (typical) - $500k duplex-$125k down-$375k mortgage at 4.6%Scenario B (modular financing) - $500k duplex-$125k down-$260k mortgage at 4.6%-$75k HELOC on primary residence-$40k loan against 401(k) (technically this would be $165k down, but you get the point)In scenario A, paying off the mortgage quickly makes zero improvement on cashflow until you pay it off completely, or refinance, and there's no point in that if your rate is locked in lower than current(or future) market rates.Scenario B could involve higher interest rates on the HELOC and the 401k loan, but you have multiple, simple, easy options for increasing your cashflow, and then you don't end up playing as much in the overpriced, volatile stock market.

It is typically much easier for you to buy "turnkey", however in my experince you will buy better quality from an owner who occupied the property than a hous that has been professionally flipped and the remodelling has been done skin deep.Cash and quick closing is not always an advantage.

What is the typical inspection period?

The cabinets that we sell for house flips are typically white or gray painted shaker doors.

Either before or after the purchase there will typically be an ISO report completed with an inspection from a third party.

You will also want to know what typical vacancy rates are like in the area, the terms of the current leases, what capital expenditures he has done recently.

The only other way I can think of right now is to try to get to get owner financing and make them believe its typically makes them more money and spreads out their income to the  life of the loan. 

Typically each condo has a few units in the building sitting on the market.

I know typically a duplex is more expensive then single family homes.My question is, is it easier to get conventional financing for that types of properties because of it's potential to produce cash flow,or at last reduce what I'm paying for the expenses out of my own pocket.?