We had a new house built approx. 1 year ago and the builder used manufactured trusses in the floor. We have a spot that runs parallel to a wall between our MBR and our Greatroom that had some excessive bounce. The builder came back in and added some additional support in attempt to help and it has, but still not to my satisfaction. My thought was to add a wall directly beneath it in our unfinished basement. We would really like to keep the floorplan open and I am looking for a way to accomplish both. I don't have much experience, so I want to use you more experienced builders as a sounding board. I am thinking that I could gain some additional support if I bonded 2 or 3 2x12's together (glue and nails/screws) to form a sturdy header board to run across the problem area, then build the wall normally beneath it. I would like to have a large walkthrough doorway to allow the area to stay "open" rather than a normal doorway. Would this work the way I need it to or am I going to have to give up my open floorplan?