WHAT!? If its outside it will disappear?! ARE YOU SERIOUS??
I'm pretty sure that objects you drop in the wild do not disappear. You can even drop junk in dungeons, its just containers which will recycle your items.
As for making a house out of junk, this is a fine tradition in Bethesda games. I remember some guy made a house out of cigarette cartons in Fallout 3. And there was one guy who used some kind of duplicated items in Oblivion, books was it? cant remember.
In Skyrim, all objects tend to get bashed around a lot no matter how heavy they are, dragon bones and gold bars can be kicked around like footballs, they just make a heavy clunking noise. You could probably create a house out of bars with shields for a roof, but it wouldnt be very practical to use it.