From exterior wall sheathing to cabinetry, plywood serves countless uses and is one of the most ubiquitous building materials, especially here in the Pacific Northwest. With so many uses and different types of plywood available, it’s important to know your options, understand the material, and pick the right product for your project.  

For our Plywood Series, we’re joined by T.R. Cauthorn, Panel Sales Manager at Hampton Lumber, a leading sustainable lumber producer based in Washington and Oregon and one of Dunn Lumber’s long-standing suppliers. With nearly 30 years spent with Hampton Lumber, plus experience working in mills and forests with Georgia Pacific, T.R. is a plywood expert.

Proper plywood installation can be make-or-break when it comes to the effectiveness and longevity of your materials. In today’s episode, T.R. gives us some do’s and don’ts when it comes to nailing patterns, and he goes in-depth on panel orientation.

Nailing patterns 

Whether you’re installing plywood as wall sheathing, roof sheathing, or underlayment, proper fastening and spacing between panels are keys to a successful installation.

T.R. recommends applying the nailing pattern recommended by the APA (The Engineered Wood Association) or any other approved grading agency. Not only does following APA standards take any guesswork out of the installation process, but it allows you to feel confident knowing the information came from one of the most respected resources in the industry.   

The fastening requirements typically contain the following elements:

  • Fastener specifics; length, diameter, type, corrosion resistance, etc.
  • Fastener spacing requirements at the perimeter of the panel
  • Fastener spacing requirements in the “field”

It’s a common misconception in plywood installation that you don’t need space between the panels. Lack of spacing, especially when plywood is exposed to the outdoors, can lead to your material buckling. It’s best to leave a gap when installing plywood as wall sheathing, roof sheathing, or underlayment, so the plywood has room to expand and contract as it naturally absorbs moisture in the elements. 

Panel orientation: scant face versus full face 

When installing plywood panels on roof trusses or floor joists, ensure they’re positioned correctly; panels are typically installed perpendicular to the roof trusses or floor joists. As with nailing patterns, follow grading agency guidelines for panel orientation.

When installing tongue and groove underlayment, you may run into the choice of scant-face plywood versus full-face plywood. Scant-face T&G underlayment has a 47 ½-inch face, which means that it was milled out of a 48-inch panel. Full-face T&G underlayment has a full 48-inch face and is machined from a 49-inch panel.  

As T.R. notes, it’s a strange anomaly that the industry hasn’t figured out more standardized plywood sizing (considering no one is designing rooms around 47 ½ or 48 inches!) In the end, whether you should use scant-face plywood or full-face plywood depends on a number of factors, including your region. In Seattle, both scant- and full-face underlayment is available, whereas in Southern California, only scant-face plywood is used. 

Want to learn more about plywood? Browse through our plywood series archive for more guidance and information.