How do I determine 1st floor walls that are bearing loads from the 2nd floor in a post & beam foundation? Are they only the exteriors?
there are no bearing walls, including the perimeter walls in a post and beam construction. The posts and beams are the supporting structure. The walls are simply filler.
hey, ignore that. I read foundation and thought building for some reason.
so, after that embarrassing answer. I'll try again.
as Mike was alluding to, typically a load bearing wall is going to run perpendicular to the 2nd story floor joists. Head to the crawl space, look for support posts within the perimeter and a beam running perpendicular to the floor joists. It would be a safe bet that any wall directly above such a beam is going to be load bearing.
If there is no support under the first floor to support a wall above, it takes some review of the design to determine if any given wall is load bearing. Obviously if not directly supported by foundation, the load capacity would be diminished but that doesn't preclude it from being load bearing entirely.