Moisture Exposure Recommendations for Wood Structural Panels

Wood structural panels like plywood and oriented strand board (OSB) are predominantly manufactured with Exposure 1 and Exterior bond classifications. This publication clarifies the difference between Exposure 1 and Exterior bond classifications and explains when each is required for different applications.

This publication is designed for: builders, contractors, engineered wood manufacturers

This publication explains how in-service moisture content affects panel performance, when strength reductions apply and the conditions where pressure preservative treatment is necessary. It includes a comprehensive reference table that matches specific moisture conditions with the correct bond classification, design considerations and treatment requirements.

Published by APA — The Engineered Wood Association.