You had provided some useful info regarding my question about putting in a tile floor on a concrete slab. I think I will take your advice and build up the floor flush with the adjoining floor. My question is this: I am assuming I will need to put 2x dimensional lumber on edge (not on flat) to start. How do I nail the lumber to the concrete on it's edge? I will probably borrow/rent a power nailer to penetrate the concrete, but I wasn't sure about nailing through the 2x edge.