I need to route some wires for wall mounting a flat screen TV, the problem is I have to cross 3 bays in the wall with no attic access because I am running these wires on the 1st floor of a 2 story house. I was thinking that I might be able to remove the subfloor on the second story to gain access to the lower story wall. Can you guys tell me if this will work? It is on an exterior wall, the floor joists are standard I beams. My fear was after I remove the subfloor The I beams may still block me from getting into the lower wall with a tape to pull the wires up and back down.