Exposure to rain or moisture causes plywood to warp, swell, or mildew, risking issues like squeaky floors or mold. Prevent problems by bagging units on-site, sweeping puddles, and using fans/dehumidifiers in wet conditions. While OSB is more durable in moisture, both plywood and OSB need spacing for expansion. The safest approach: keep plywood dry. In humid regions like the Pacific Northwest, store in dry areas or bag during wet weather.
The plywood grading process starts at the mill, separating logs by species (Group 1: Douglas fir, larch; Group 2: hemlock, spruce) and diameter. Group 1 species are used for marine-grade or Structural I panels, while Group 2 serves as cores/back veneers.
Logs are peeled, dried to 7-8% moisture, then graded to maximize recovery. Veneers are upgraded via patching/puttying (e.g., B to A grade, C to C-plugged). The goal: create the highest-grade plywood from raw materials, with recovery being key in wood production.
