The National Lumber Grades Authority (NLGA) was incorporated under Letters Patent by the Minister of Corporate and Consumer Affairs on January 12, 1971, as the organization responsible for writing, interpreting and maintaining Canadian lumber grading rules and standards.

The NLGA rule is approved and enforced by the Canadian Lumber Standards Accreditation Board (CLSAB) and by the American Lumber Standard (ALS) Board of Review. The approval enables acceptance under Canadian and US building codes.