1994 UBC:

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Slide 63 of 67

Notes:

The 1994 UBC stated that the nail should “not fracture the surface of the sheathing”.

The 1997 UBC has clarified the language to state that the “head or crown of the nail is flush with the surface of the sheathing.”
- Nails installed with their heads resting on but not into the sheathing can cause problems for roofing and other finishes.
- Nails should be driven so that the top of the nail is flush and not above the surface of the sheathing.

What happens during an earthquake?
- Nails will try to pull through the thickness of wood structural panel sheathing during an earthquake
- For this reason, it is important that nails should be driven flush with the surface of the sheathing and not overdriven and that they be placed correctly
- Overdriven nails:
  - Reduce the shear wall strength by effectively reducing the thickness of the sheathing.
  - At panel edges, overdriven nails allow easier nail punch-through.
  - At intermediate studs, overdriven nails allow easier panel buckling.
- Why are nails overdriven?
  - Excessive air pressure in the nail gun
  - Too long of a driving pin on the nail gun.
  - When the spacing and framing member thickness allow, nails should be added to replace any overdriven nails.