The Association's Grading Rules for Western Lumber establishes standards of size and levels of quality in conformance with the American Softwood Lumber Standard PS 20. WWPA is certified as a rules writing and inspection agency by the Board of Review, American Lumber Standard Committee and is approved to provide mill supervisory services under its rules and the rules of the West Coast Lumber Inspection Bureau, the Redwood Inspection Service, the National Lumber Grades Authority for Canadian Lumber and the NGR portion of the Southern Pine Inspection Bureau Rules. In addition, WWPA is approved to supervise finger-jointed and machine stress-rated (MSR) lumber.
Interpreting Grade Marks
WWPA uses a set of marks to identify lumber graded under its supervision. The grade marks are stamped on the lumber and appear near the ends of the product:
15% maximum moisture content
19% maximum moisture content
over 19% moisture content (unseasoned)