Lumber grading rules are a set of criteria used to determine how various characteristics, such as wane or knots, affect the structural performance of dimension lumber or the aesthetic value of Appearance Grades. Lumber manufacturers are responsible for grading the lumber to these rules and WWPA, as part of the American Lumber Standards system, helps assure that Western lumber meet stated product quality standards.
WWPA - Western Wood Products Association a trade association representing softwood lumber manufacturers in the 12 Western states, from the Canadian border south to Mexico and from the West Coast to the Black Hills of South Dakota with services in Alaska, is the leader in the West in lumber grading, rules writing and quality control inspection.
BUYER BEWARE WARNING: The pattern measurements below are WWPA industry standards. HOWEVER individual mills often have their own pattern standards which vary from the norm (usually smaller). When you get ready to buy be sure to ASK for the exposed width to make sure you are buying enough SQFT of cedar siding to complete the job!