Canadian structural lumber is produced under a rigorous national grading and quality assurance system. The National Lumber Grades Authority, or NLGA, establishes the grading rules for Canadian lumber, while agencies accredited by the Canadian Lumber Standards Accreditation Board, or CLSAB, supervise grading, inspection and grade stamping at the mill level. Each piece of Canadian dimension lumber is assessed for structural use and marked with key information such as species group, grade, moisture condition, mill identification and grading agency, giving buyers and specifiers clear evidence of quality and performance.
For the UK market, Canadian lumber grading provides an important technical bridge to familiar strength classes such as C16 and C24. Canadian lumber is graded under NLGA rules and supported by recognised design values, certification and export documentation, helping UK merchants, engineers, builders and timber-frame manufacturers specify Canadian products with confidence. This connection is also reflected in the term CLS — Canadian Lumber Standard — a familiar name in the UK timber trade and a reminder of the long-standing relationship between Canadian lumber and UK construction practice.
Canadian timber may also be graded to GS and SS grades, either in Canada or in the UK, in accordance with BS 4978: ‘Visual strength grading of softwood. Specification’.