Solid blocking is required for floor joist that exceed what nominal size?

Solid blocking is required for floor joist that exceed what nominal size?

• A. 2 x 8
• B. 2 x 10
• C. 2 x 6
• D. 2 x 12

Answer: (D)

Blocking between floor joists provides lateral support and helps distribute loads, preventing joists from twisting or spreading under load. When joists become deeper and stronger (exceeding a 2-by-12 nominal size), they are more prone to deflection and rotation without mid-span bracing. Solid blocking at proper intervals stabilizes the joists, keeps the floor system stiff, and gives a solid nailing base for the subfloor. So, the rule in this context is that blocking is required once floor joists exceed the 2-by-12 nominal size, because the increased depth makes mid-span support more critical to maintain integrity. The smaller sizes listed don’t automatically trigger blocking by this standard; the need there is governed by other factors like span and load, rather than size alone.

Blocking between floor joists provides lateral support and helps distribute loads, preventing joists from twisting or spreading under load. When joists become deeper and stronger (exceeding a 2-by-12 nominal size), they are more prone to deflection and rotation without mid-span bracing. Solid blocking at proper intervals stabilizes the joists, keeps the floor system stiff, and gives a solid nailing base for the subfloor.

So, the rule in this context is that blocking is required once floor joists exceed the 2-by-12 nominal size, because the increased depth makes mid-span support more critical to maintain integrity. The smaller sizes listed don’t automatically trigger blocking by this standard; the need there is governed by other factors like span and load, rather than size alone.