Siding Grades

Figure: Wood Siding Grades
Product Grade Description Moisture Content
Standard Clear Grades - Western Red Cedar
Bevel Siding Clear VG (vertical grain) Free of knots and imperfections; for use where the highest quality appearance is desired. MC-15 (15% or less- most pieces 12% or less)
A Grade Includes some mixed grain and minor growth characteristics.
B Grade Includes mixed grain, limited characteristics and occasional cutouts in longer pieces.
Rustic Similar to A grade, but graded from sawn face.
C Grade Admits larger and more numerous characteristics than A or B grades
Boards (Finish, Trim) Clear Finest appearance with clear face, few minor characteristics.
A Grade Recommended for fine appearance. May include minor imperfections or growth characteristics.
B Grade Permits larger and more characteristics, but may have short lengths of fine appearance.
Standard Knotty Grades - Western Red Cedar
Bevel Siding, Boards, Channel, T&G, etc. Select Knotty For fine knotty appearance 19% or less
Quality Knotty Permits more pronounced characteristics and has occasional cutouts in longer pieces.
Select Merchantable Has fine appearance and includes knots and minor markings Unseasoned
Construction Limited characteristics allowed to assure high degree of serviceability.
Standard Allows more characteristics than construction
Standard Softwood Grades (all species except redwood)
All board patterns C Select Mixed grain, a few small knots allowed. For uses when a fine finished appearance is required. MC-15 (15% or less- most pieces 12% or less)
D Select Mixed grain, slightly larger knots than allowed in C Select.
#2 Common Has fine appearance and include knots and minor markings 19% or less
#3 Common Limited characteristics allowed to assure high degree of serviceability.
#4 Common Allows more characteristics than #3. Used chiefly for serviceability rather than appearance.
Product Grade & Description Moisture Content
Standard Clear Grades - Western Red Cedar
Bevel Siding Clear VG (vertical grain): Free of knots and imperfections; for use where the highest quality appearance is desired. MC-15 (15% or less- most pieces 12% or less)
A Grade: Includes some mixed grain and minor growth characteristics.
B Grade: Includes mixed grain, limited characteristics and occasional cutouts in longer pieces.
Rustic: Similar to A grade, but graded from sawn face.
C Grade: Admits larger and more numerous characteristics than A or B grades
Boards (Finish, Trim) Clear: Finest appearance with clear face, few minor characteristics.
A Grade: Recommended for fine appearance. May include minor imperfections or growth characteristics.
B Grade: Permits larger and more characteristics, but may have short lengths of fine appearance.
Standard Knotty Grades - Western Red Cedar
Bevel Siding, Boards, Channel, T&G, etc. Select Knotty: For fine knotty appearance 19% or less
Quality Knotty: Permits more pronounced characteristics and has occasional cutouts in longer pieces.
Select Merchantable: Has fine appearance and includes knots and minor markings Unseasoned
Construction: Limited characteristics allowed to assure high degree of serviceability.
Standard: Allows more characteristics than construction
Standard Softwood Grades (all species except redwood)
All board patterns C Select: Mixed grain, a few small knots allowed. For uses when a fine finished appearance is required. MC-15 (15% or less- most pieces 12% or less)
D Select: Mixed grain, slightly larger knots than allowed in C Select.
#2 Common: Has fine appearance and include knots and minor markings 19% or less
#3 Common: Limited characteristics allowed to assure high degree of serviceability.
#4 Common: Allows more characteristics than #3. Used chiefly for serviceability rather than appearance.

Note: Problems occur with siding grades that are unsuitable for the job. To avoid problems, use select grades. These grades apply to all lumber graded under the rules of Western Wood Products Assoc. (WWPA), West Coast Lumber Inspection Bureau (WCLIB), or National Lumber Grades Authority (NLGA) of Canada. The term “characteristics” refers to knots, wane, pitch pockets, irregular grain, etc. Lumberyards may use other terms for their siding grades, but there’s little chance of knowing what will be delivered or how it will perform. Ask for equivalents to the standard grades established by industry trade associations shown above.

Cheap or ungraded siding usually warps, shrinks, splits, and otherwise deteriorates far quicker than premium-grade material.


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