Which structural element directly supports the floor sheathing?

• A. Rafters/Joists/Beams
• B. Columns
• C. Foundations
• D. Earth

Answer: (A)

The floor sheathing is directly supported by the horizontal floor framing members, the joists. The sheathing is nailed to the tops of the joists, and together they form the floor surface that carries loads from people, furniture, and equipment down to the supporting structure. While beams may carry the joists and foundations support the structure overall, the joists are the elements that directly bear the floor sheathing. Roof rafters handle the roof above, foundations transfer loads to the earth, columns carry vertical loads, and earth isn’t a structural member in the framing. So the option that includes floor joists as the direct support best describes how the floor sheathing is supported.