New Memos on Lumber Grade Stamps

The Canadian Lumber Standards Accreditation Board (CLSAB) recently released memos to building officials regarding lumber grade stamps. The content of those memos is below.

Imported Structural Lumber Enquiries about Plywood and OSB

The price and availability of lumber is introducing a lot of creativity around sourcing products.

Every piece of structural lumber needs to be stamped with a CLSAB approved grade mark. This requirement appears in CSA-O141 Softwood Lumber where it states that softwood lumber may be designated as Canadian Standard Lumber if the following conditions are met:

  • The lumber complies with the minimum requirements of CSA-O141.
  • The lumber is graded in accordance with grading rules approved by an accreditation board (CLSAB).
  • The lumber is inspected and identified in accordance with the regulations of that accreditation board (CLSAB).

Two exceptions are as follows:

  • D.Fir-L or Hem-Fir grown in the United States and stamped with an American Lumber Standards Committee Accredited Agency grade stamp as CSA-O86 provides this equivalency.
  • For all other imported lumber, the homeowner or builder must consult with a structural engineer to determine design values for the lumber and then each piece must be inspected by a CLSAB Accredited Agency to ensure the material meets the required NLGA grade.

If you have questions about plywood or OSB, the APA – The Engineered Wood Association ( is the organization to contact. The APA Help Desk can be contacted by email at or by phone at 253-620-7400 from Monday to Friday, 7 am – 4 pm PST.

Grade Stamp not recognized by the National Building Code of Canada

This grade stamp (below) was recently observed in Ontario. This grade stamp is not valid for structural use in Canada as:

  • the National Building Code of Canada has no recognized design values for Austria Spruce, and
  • WCLB is not an Accredited Agency of the CLSAB.

If you have questions about these memos, contact or 613-482-2480.