I’m going to be building a house with 12″ double stud walls with the exterior wall being load bearing. The foundation wall is 8″ concrete, 3″ continuous polysio, 1×4 strapping, GWB.

I’m trying to figure out what the section will look like at the basement stairs. Specifically at the intersection of the basement wall and 1st floor wall. If there isn’t a floor system sitting on the foundation, how is the interior wall supported?

I’m currently playing with 3 ideas:
1- The interior wall hangs from the exterior wall using plywood gussets, similar to a larsen truss.
2- Include a floor header, 12″ thick that sits on the foundation. Properly braced to support the interior wall.
3- Switch my 1×4 basement wall to 2×4 on flat. Have them extend up from the basement to support the bottom plate of the interior wall.

Thanks for any ideas you may have.