Double Top plate Question.

[Tinga]

I've looked around the net and scoured pictures here and I can't seem to find a good picture to answer my question.

While we are still >5 years from building, we've somewhat settled on a floor plan. Most of the interior walls are to scale, minus the stairs. I had to mock some things up to get the husband to visualize what I was seeing in my head.


We're (soft) planning on a 35x45 1 1/5 story, with an open Living room/dining room area:




One of the questions I keep running into is the double top sill plate and rim joist for the open living area section . Local codes really poo-poo on balloon framing, so the plan was to run with platform framing with a 3'-4' kneewall for the "2nd story' and go with a local truss company.
My confusion is at the transition from the living room area to the 2nd story floor joists on the OUTTER WALL. In the "open living room area" would you double up on the rim joists with a plywood spacer and just frame the knee wall on top of that? How would it attach? I'm guessing there is an easy answer that stems from my lack of "hands on".

[John Raabe]

If you are doing a truss roof you should be able to do a 10' tall 2x6 frame wall in the great room area. If the wall gets taller than that you may need to have ties across or other ways of bracing.