Why does an inspector note the direction that floor joists run?

Load travels perpendicular to the members that carry it, so joist direction tells the inspector where the load lands. Joists bear on the walls or beams at their ends and deliver essentially nothing to the walls running parallel beneath them. That single observation lets an inspector standing in a basement predict which walls on the floor above are likely bearing and which are probably partitions — the walls running perpendicular to the joists above are the candidates. It is the fastest way to evaluate a removed wall, a proposed removal, or a new opening, and it explains why a post or beam appears where it does. The direction also identifies which walls need continuous support down through the structure to the foundation, which is what turns a question about a wall into a question about the whole load path.

Joists bear at their ends and deliver load to the walls beneath those ends, so their direction identifies which walls below are likely carrying load rather than acting as partitions.

Floor joists transfer load at their bearing ends to walls or beams below. Walls perpendicular to the joists above are potential bearing walls; walls parallel to them typically are not. Load must be continuous to the foundation.

Perpendicular Carries, parallel usually does not. Stand where the joists end and you are standing on the load path.

Perpendicular means potentially bearing, not certainly bearing. Confirm by looking for continuous support below and framing above.

• •Treating perpendicular walls as certainly bearing rather than likely
• •Not checking whether support continues below to the foundation
• •Overlooking joist direction before assessing an alteration