Using APA Structural I Rated Sheathing: Building With LP Structural Solutions for Added Strength

When the build requires greater strength, look for an OSB roof and wall sheathing that is APA Structural I Rated Sheathing-also known as Struc I-for increased structural reliability. What is APA rated sheathing? This valuable designation is a "stamp of approval" that verifies the panels have passed APA's manufacturing and performance standards.

LP WeatherLogic® Air & Water Barrier has endured rigorous performance testing and has earned the Structural I rating from the APA. “Products with the Struc I designation are manufactured for greater cross-panel strength and stiffness,” says Jeff Yelle, Director, OSB/EWP Technology, LP Building Solutions. 

Understanding Structural I Performance Requirements

Some builds require enhanced wall racking and floor and roof diaphragm capacity. Building in areas of high wind speeds or prone to earthquakes may require the added performance of Structural I sheathing.

"Imagine you're building a wall; you have a giant rectangle and your goal is to make it into a parallelogram," explains Yelle. "Push the wall near the upper-right hand corner-the resistance you're feeling is called racking. Its influence-such as how and where the wall is fastened-determines racking performance." Yelle further explains that shear walls keep the house from falling in during a hard wind.

When to Use APA Rated Sheathing

LP WeatherLogic wall and roof sheathing is manufactured for use when extra capacity and greater strength is needed. In addition to Structural I wall and roof sheathing, LP Legacy® Premium Sub-Flooring in 23/32 Performance Category is APA Structural I Rated Sheathing, which makes it a great sub-floor option for builds that require exceptional load bearing or stiffness.

“Typically, our Struc I LP WeatherLogic and LP Legacy products are used in specialized engineering builds, like engineered shear walls and engineered horizontal diaphragms,” says Yelle. “Architects can design such elements that take advantage of the superior strength.” For example, the last thing you want to hear in a custom home is a squeaky floor. Learn how you can prevent such nuisances by using stronger materials.

Yelle recommends using Structural I LP WeatherLogic and LP Legacy panels in areas prone to hurricane-category winds and seismic activity. "Lateral forces from storms and earthquakes can twist and compromise the integrity of the structure, making shear and racking performance more important," says Yelle. "There is a lot of designing to meet seismic building requirements, and our Struc I products are very popular in California."

Reading the Label for APA Sheathing and APA Span Ratings

 We asked construction expert Kyle Stumpenhorst of Rural Renovators for advice on reading the product label for sub-floors to ensure the proper build.

"There are two numbers separated by a slash," explains Stumpenhorst. "The number on the left is used for roof sheathing. The number on the right is for sub-flooring. Both numbers indicate the APA span rating, which is the maximum recommended spacing allowed between the supports. The further the supports are spaced, the thicker your panels need to be."

Stumpenhorst always keeps a product’s ability in mind when weighing options. “The quality of the products makes my job easier,” he says. “For example, LP WeatherLogic panels, with their built-in WRB, install like regular sheathing for potential savings while keeping my jobsites cleaner and more professional.” Stumpenhorst found great success using LP WeatherLogic panels for both roofing and wall sheathing in the Oregon Music Garage product. Read more about the build here.

Why Use Structural I Rated Sheathing Products From the LP Structural Solutions Portfolio?

Not all new builds require greater cross-panel strength and stiffness; however, as Yelle says, "Why not use the product that goes beyond the minimum expectations and provides more confidence and care? It's harder to manufacture a Struc I panel because it goes through a higher level of scrutiny."

Using LP Structural Solutions products, such as LP WeatherLogic panels and 23/32 thickness LP Legacy sheathing, can help your build stand up to whatever comes its way with increased structural reliability. See how the LP Structural Solutions portfolio can help you Defend Your Build®.