Imagine walking across a beautiful floor in a well-built home. You marvel at the character of the wood grain and the perfection of the finish. The floor feels sturdy and smooth under your feet. Though the solid wood flooring that you’re seeing and feeling gets all the glory, the secret of the system lies beneath the surface.

It starts with right-size floor joists, that deflect little and don’t bounce beneath your feet. Equally important is pairing the joist system with the right subflooring. Subfloor sheathing provides structural stability and a stiff surface to support a long-lasting finished floor. And subfloor installation matters a lot. Regular nails are hardly adequate. Most builders turn to a combination of ring-shank nails or screws and glue. In this article, however, we’re going to look at the material choices. There’s been a bit of innovation in subflooring, and it all points toward one material: oriented strand board, or OSB.

Subfloor sheathing panels

When buying a commodity sheathing panel suitable for both floors and roofs, you will notice an ink-stamp marking on the panel that looks like a fraction, likely 24/16. This pair of numbers tells you the maximum joist spacing for which the sheathing was designed, in inches. The first number (24) applies only to using the material on a roof, and the second (16) applies to using it on a floor. Suppose you purchase conventional, commodity-grade 3/4-in. sheathing stamped 24/16 to use as a subfloor. That means you should install it on joists spaced no more than 16 in. apart and install blocking at the seams to prevent deflection along the panel edges. However, blocking is unnecessary when using tongue-and-groove panels, and all panels manufactured explicitly for use as subflooring—what we’re going to look at here—come with tongue-and-groove edges.

Although most floors…