Vertical vs. Horizontal Plywood When Framing

Vertical Ease

• One advantage to putting the plywood on in a vertical orientation when sheathing the wall is that it minimizes the amount of cutting you have to do. Cutting boards to fit is time consuming and always leaves the possibility of making errors. Plywood is available in both 4X8 and 4X9 sizes -- which means it may be tall enough to completely sheath a 4-foot section of your wall.

Shear Strength

• Vertical sheathing has more inherent shear strength than horizontally oriented plywood. One reason for this is that none of the edges of vertically oriented plywood float. Instead, they are all fastened to studs, the top or sill plate of the wall. The other problem is that the joints in a horizontally framed wall are parallel to the shear force. This provides a weak point, where the force could cause the wall to fail.

Substrate

• Horizontal sheathing provides a better substrate for exterior wall coverings. For instance, if you plan on using stucco on the exterior of your home, it's recommended that the plywood be installed horizontally. However, you also need to install blocking behind the plywood. Blocking refers to small pieces of wood that you install horizontally between the studs along the joint lines, so you can fasten the edge of the horizontal plywood to a support beam.

Shared Downfalls

• Ultimately, vertical and horizontal plywood framing techniques both share the basic downfalls of the material. Compared to other sheathing options, plywood walls are still very subject to moisture damage and may warp if continually subjected to the damp. In addition, there is no fire-resistance benefit at all to be had when using plywood sheathing, which is one of the factors considered by many contractors when deciding on sheathing material.