Any way to get fractional financing on residential prop?

[Tiffany Shan]

Hi-

Let's say me and a friend want to buy a SFH to live in together instead of renting. I know the typical response is "NO GOD NO don't buy a property with a friend." :) Let's set aside the 'don't mix business with friendship' advice for now and focus on how we'd theoretically finance that purchase.

Does anyone know any way to fractionalize a mortgage? For instance, in the very ideal case, if the home is $300K, we each get a $150K mortgage? Or barring that possibility, a way to use financing while insulating our credit from each other so that if the worst happens, my friend disappears, and I can't cover her share, I'm not totally screwed? 

I realize this question must come off as IMPOSSIBLY naive...! But here in San Francisco buildings (especially 2-units, but again let's pretend it's a SFH) are held by tenancy-in-common and people are given fractional TIC loans (typically 5 or 7/1 ARMs, .5-1% higher).