06/19/2026
APA Rated Sturd-I-Floor® Framing System
This technical illustration demonstrates the structural layout and assembly of a residential or commercial flooring system using APA Rated Sturd-I-Floor® panels. It showcases how subfloor panels integrate with the underlying support structure (including rim boards, joists, and trusses) and the overlying wall frames and floor finishes, emphasizing proper alignment, panel orientation, and edge support.
Key Components
APA Rated Sturd-I-Floor® Panels: Combined subfloor-underlayment panels designed for durability and strength, indicated with their recommended on-center (o.c.) spacing options of 16, 20, or 24 inches.
Strength Axis Orientation: A directional indicator showing that the long dimension of the panels must run perpendicular to the underlying floor supports for maximum structural integrity.
Tongue-and-Groove Edges: Formed edges along the panel joints that interlock to distribute loads smoothly between panels, reducing the need for 2-inch lumber blocking between supports.
Floor Supports: The illustration depicts various compatible framing options, including traditional 2x joists, engineered I-joists, and floor trusses spaced at 16, 19.2, or 24 inches o.c.
2x Rim Joist / APA Rim Board: The structural perimeter member that provides lateral support, closes off the ends of the floor joists, and transfers vertical loads to the foundation.
Wall Framing & Finishes: Represents the final layers of the assembly, showing vertical wall studs secured above the subfloor, alongside a cutaway of the carpet and pad installation.
Concept Summary
Overall, the diagram serves as a comprehensive guide for proper floor construction techniques. It highlights how selecting engineered wood products like tongue-and-groove Sturd-I-Floor® panels helps create a continuous, rigid diaphragm. By showing the relationship between the concrete foundation, the engineered framing components, and the finish materials, the illustration emphasizes efficiency, structural continuity, and code-compliant span ratings in modern building design.