Plywood Sturd-I-Floor is designed for use in single-layer floor construction beneath carpet and pad. The span rating is stamped on each panel. Glue-nailing is recommended for Sturd-I-floor panels, though panels maybe nailed only. Install with smooth side up. Stagger panel end joists. Spacing of 1/8" is recommended at panel ends and edges. Sturd-I-Floor also features APA Quick-Fit™ Tongue & Groove design so panels fit together quickly and easily, for even faster installations.