CSLB General Building (B)Framing and CarpentryMedium
During a shear wall inspection, the building inspector rejects a wall panel because many of the 8d common nails along the panel edges were driven so deep that the nail heads broke through the sheathing surface. Why does this cause a code violation?
- AOverdriven nails reduce the effective shear transfer capacity of the sheathing-to-framing connection
- BOverdriven nails void the fire rating of the wall assembly
- COverdriven nails increase the shear capacity beyond code limits, requiring re-engineering
- DOverdriven nails are only a cosmetic issue and do not affect structural performance
Show answer & explanationAnswer & explanation
Correct answer: A. Overdriven nails reduce the effective shear transfer capacity of the sheathing-to-framing connection
When a nail head is driven through the panel face, it tears the wood fibers and reduces the panel's ability to resist lateral (shear) loads, lowering the wall's design shear capacity. Shear wall values in code tables assume nails are set flush, not overdriven or underdriven.
Why the other options are wrong
- B. Fire rating is unrelated to nail depth in a shear wall assembly.
- C. Overdriving weakens, not strengthens, the connection.
- D. This is a structural issue, not merely cosmetic, since it affects load capacity.
Shear Wall Nailing Quality
Shear wall capacity depends on nails being driven flush with the sheathing surface; overdriving damages wood fibers and reduces the connection's lateral load resistance.
- Nail heads should be flush, not countersunk into sheathing
- Overdriving reduces shear capacity and can fail inspection
- Underdriven (proud) nails also reduce performance and require correction
Memory trick: 'A buried nail head, a broken shear thread.'