It is hard to understand some common details on residential construction. Here is one. Most roofs are built with roof trusses, which can have long span like over 20 or even 30 feet. The bearing wall take quite a big load. But when the floor joist underneath is parallel to the bearing wall...
I have a very long span floor (29')for a residential house. The floor joists are supported by existing 2x4 stud wall. The studs are spaced at 16" oc (HF #2). By using DL=15psf, LL=40psf, my analysis shows the single 2x4 top plate can not carry the load. I do not think it is right to consider...