When framing wall studs 24" on center and the joists are running north and south you layout the wall studs to sit directly above the 24" joists. What do you do for the outside walls running above the east/west rim joist? Is only having the rim joist available to set the 24" on center studs acceptable or do you need to install additional structural support?
Your east west wall as the floor is concerned is a non bearing wall. For the situation, you want to address, I usually double the rim joist to add a little width under the subfloor to support the wall above. If the wall above is a bearing wall, the doubling of the rim joist should handle the load as well as long as the load is transferred to the foundation.