The NLGA “Standard Grading Rules for Canadian Lumber” permit lumber to be dressed to sizes below the standard sizes (38 x 89 mm (2” x 4”), 38 x 140 mm (2” x 6”), 38 x 184 mm (2” x 8”), etc.) provided the grade stamp shows the reduced size.
This Sentence permits the use of the span tables for such lumber, provided the size indicated on the stamp is not less than 95% of the corresponding standard size. Allowable spans in the tables must be reduced a full 5% even if the undersize is less than the 5% permitted.