I’m trying to create a simple warehouse tower, with multiple floors, having some interior walls.
Since actually upper-floor single wall canno’t be build and use automatic wall will simply put it in the edge of the building, I placed only the floor I need for the wall to be build as I wanted:
But when using the automatic wall tool, that errors came out:
Hope it can help 
At this stage in the build tool development, I think your best bet is to build the building without interior walls, but then go in with the slab toll after the building is already built. Another thing to try is adding the full second floor with a stripe missing all the way across the floor plan for a full interior wall. I was able to get that to kind of work, and then I place a door after I had clicked raise wall. Sometime using that approach, though, the template will be broken and the hearthlings won’t finish.
It’s just what i’ve done 
