Best Plywood for Subfloor: Thickness & Ratings

Structural Subflooring

Your subfloor is the structural foundation for your finished flooring (hardwood, tile, carpet). Squeaky floors, bouncy spots, and tile grout cracks are usually caused by an inadequate subfloor.

Here is how to select the right plywood panel for a sturdy, squeak-free floor.

OSB vs. Plywood Subflooring

• OSB (Oriented Strand Board): The most common subfloor material used by tract-home builders today. It is cheap and uniform. However, if OSB gets wet during construction, the edges swell and flake, requiring extensive sanding before finished flooring can be laid.
• CDX Plywood: CDX stands for C-grade face, D-grade back, and X-grade glue (designed for temporary moisture exposure). CDX plywood dries out quickly if it gets wet, retaining its structural integrity much better than OSB.

Standard Subfloor Spacing and Sizing

• 16" On-Center Joists: Use 23/32" (3/4") Tongue and Groove (T&G) plywood. T&G sheets lock together along their long edges, preventing the panels from flexing independently.
• 24" On-Center Joists: Use 7/8" or 1-1/8" plywood. Spacing joists further apart requires thicker panels to eliminate vertical deflection.