Grading

Dimension lumber grading rules limit natural characteristics and manufacturing imperfections that affect the strength and utility of the piece. The grades are based on a visual or digital scan evaluation of each lumber piece.

Dimensional Lumber Grades

WWPA grades for dimension lumber are established by the American Lumber Standard Committee, Inc., in accordance with DOC (U.S. Department of Commerce) Product Standard 20. The grading rules are published in the Western Lumber Grading Rules book. Dimension Lumber grades are divided into the following classifications:  

Structural Light Framing
(2x2 through 4x4, used where high-strength design values are required in light framing sizes, such as in engineered wood trusses.) Grades are:

SELECT STRUCTURAL
No. 1 & BTR (DF-L, DF & Hem-Fir species only)
No. 1
No. 2
No. 3

Light Framing
(2x2 through 4x4, basic framing lumber, as used in most light-frame construction, e.g. wall framing, sills, plates, cripples, blocking, etc.) Grades are:

CONSTRUCTION
STANDARD
UTILITY

Stud
(2x2 through 4x18, an optional grade intended for vertical use, as in load bearing walls.) The grade is:

STUD

Structural Joists & Planks
(2x5 through 4x18, intended for engineering applications for lumber 5" and wider, such as floor and ceiling joists, rafters, headers, small beams, trusses and general framing applications. Grades are:

SELECT STRUCTURAL
No.1 & BTR (in Douglas Fir, Douglas Fir-Larch, or Hem-Fir species only.)
No. 1
No. 2
No. 3