What Provides Shear Wall Strength?

• Lumber

• Sheathing

• Fasteners

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How Shear Walls Provide Strength

• What provides the strength of a shear wall?
  • The strength of the shear wall depends on the combined strengths of its three components:
    • lumber,
    • sheathing and
    • fasteners.
  • This section will discuss lumber and sheathing. The following section will discuss fasteners.
  • You will learn how each component affects the strength of the shear wall and how strength is lost by improper installations.

• It is critical to install the correct length of shear wall for the particular strength of the material used
  • For shear wall sheathing, the 1994 Uniform Building Code (UBC) permits the use of
    • gypsum wallboard,
    • cement plaster,
    • fiberboard,
    • wood particleboard,
    • plywood and oriented strand board.
    • Previous editions of the UBC also allowed wood lath and plaster, horizontal and diagonal sheathing for shear walls.
  • All of these sheathing materials provide different strengths. The UBC shows these strengths in pounds per foot of wall length.
  • In order to correctly install a shear wall, the wall must be the correct length for the sheathing material selected

• Fasteners
  • Fasteners for shear wall construction may be staples, screws or nails. This will be discussed in a later section
  • There are two important things to remember about fasteners:
    • Denser lumber species provide stronger fastener strengths.
    • Values for shear wall strengths assume a dense lumber species like Douglas fir-larch or southern pine.
  • Thicker framing members also increase wood structural panel sheathing strengths.