Slide 11 of 67
Notes:
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.
