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USA & Canada

Timber Grades and Specifications


Clear Grades

Clear cedar has a limited number of natural characteristics and is specified when appearance of the highest quality is desired. Clear grades of timbers are normally supplied green (unseasoned). When required, seasoning is achieved by air-drying.

Knotty Grades

Knotty cedar presents a more rustic appearance and is typically supplied green (unseasoned) in the appearance and structural grades. When required, seasoning is achieved by air-drying except for grades of Light Framing and Structural Joists and Planks which are available kiln-dried.

Surface Textures

Saw Textured The saw textured surface, obtained during the milling process which uses either circular or band saws, is present on all four sides.

Rougher Headed The lumber receives its texture from a milling process which uses roughened planer knives. The rough texture is clearly visible on all four sides.

Surfaced Four Sides (S4S) The smooth surface on all four sides presents a uniformly sized product with a high quality appearance. Sizes from 2 x 4 (51 mm x 102 mm) up to 6 x 6 in. (152 mm x 152 mm) are generally available. Larger sizes are produced on special orders.

No. 2 and Better Clear

This grade should be specified when the finest quality rough lumber is desired. The lumber is sound and well manufactured. Its natural characteristics do not detract from the woods fine appearance.

Grading Rule Paragraph
PLIB – Export R List 401

D and Better Clear

This grade consists of D Clear, C Clear, and B Clear.

The C and Better Clear grade offers good appearance in high quality, well manufactured lumber. Suitable for high quality landscape structures and as exposed posts and beams in heavy timber construction. In most cases, this grade is sold with a specified allowance of D grade.

D Clear grade permits larger and more numerous natural characteristics which are widely accepted in the construction of outdoor structures. Some pieces of D Clear may require trimming to yield clear lengths for the intended use. Available surfaced or rough textured.

Grading Rule Paragraph
NLGA 203 b,c,d
WCLIB 150 b,c,d
WWPA 10.11, 10.12, 10.13

Appearance Knotty

A non structural product manufactured to meet the appearance requirements of quality projects. This material has highly restricted wane allowances to give well defined corners. Contains no holes or other characteristics. Represents good value for appearance end uses. Available rough sawn or rougher headed in nominal 2″ (51mm) and thicker sizes.

Note: Upon request, Appearance Knotty timbers are available with structural grading. Be certain to specify Appearance Knotty structural lumber when strength characteristics are required.

Grading Rule Paragraph

No. 2 and Better Structural

Material of this grade is evaluated for structural strength characteristics. The classification includes pieces meeting the grades of Select Structural, No. 1 Structural, and No. 2 Structural. Lumber of this grade is intended for engineered applications where strength is more important than appearance. Available surfaced or rough textured.

Grading Rule Paragraph
5″ and thicker, with more than 2″ greater than thickness
NLGA 130 a,b,c
WCLIB 130 a,b,cc
WWPA 70.10, 70.11, 70.12

Width less than 2″ greater than thickness
NLGA 131 a,b,c
WCLIB 131 a,b,cc
WWPA 80.10, 80.11,80.12

Note: Graded as Light Framing

Graded as Structural Joists and Planks

Standard Beams, Posts and Timbers

Timbers of this grade are intended for general construction purposes where serviceability is more important than appearance. No structural values are assigned. Available surfaced or rough textured.

Grading Rule Paragraph
5″ (127mm) and thicker
NLGA 131 d
WCLIB 131 c
WWPA 81.11

NLGA – National Lumber Grades Authority
WCLIB – West Coast Lumber Inspection Bureau
WWPA – Western Wood Products Association
PLIB – Pacific Lumber Inspection Bureau


Thickness and Width
Nominal (in.)Nominal (mm)Rough (in)Rough (mm)Dressed (in.)Dressed (mm)
Over 12Over 3051/4 off6 mm off1/2 off13 mm off

Note: Full sawn timbers have the same dimension as nominal.

Grade Classifications

Depending upon size, Western Red Cedar is classified as Light Framing, Structural Joists and Planks, Beams and Stringers, or Posts and Timbers. In general, the grades referred to herein are rough sawn.

Light Framing is lumber 2″ to 4″ (51 mm to 102 mm) thick and 2″ to 4″ (51 mm to 102 mm) wide either rough sawn or surfaced four sides (S4S).

Structural Joists and Planks are rectangular members 2″ to 4″ (51 mm to 102 mm) thick, 5″ (127 mm) and wider, either rough sawn or surfaced four sides (S4S).

Beams and Stringers are rectangular members, either rough sawn or surfaced, 5″ (127 mm) and thicker with width 2″ (51 mm) greater than thickness.

Posts and Timbers are square members, either rough sawn or surfaced, 5″ (127 mm) by 5″ (127 mm) and larger with width not more than 2″ (51 mm) greater than thickness.

Please contact a WRCLA Retailer for more information on purchasing timbers.


Timber Specifications

Cedar of all the foregoing grades and surface textures is manufactured by members of the Western Red Cedar Lumber Association (WRCLA). To ensure that the cedar you specify meets the appropriate grade, be certain to specify WRCLA member production. This brochure will help you to select the right grade for the job. A typical sample specification is given below.

Specifying Wester Red Cedar for Timber Construction and Landscape Structures

The following information is required when ordering:

Specification Information RequiredSample Specification
Western Red Cedar
WRCLA Western Red Cedar
Product Pattern and Intended Use:
Timbers are used in many structures such as commercial, industrial and residential buildings; and in engineered and landscape structures. Specify the surface finish by choosing Surfaced Four Sides (S4S) rough sawn, or rougher headed
Rough Sawn
Specify the size of the product.
6 x 8 Full Sawn
The grade of the product Knotty governs its overall quality. Refer to WRCLA specification literature or grading rule books for available grades.
Appearance Knotty Structural timbers
Grading Agency Paragraph:
To ensure that the product meets a written standard, an agency grading rule paragraph or equivalent grade should be referenced.
NLGA 130c
WCLIB 130cc
upgraded for appearance qualities
Moisture Content:
Specify whether the product is to be green (unseasoned) or dried.
Surface to be Exposed:
Specify the application orientation to assist the supplier in shipping the right product for the job.
Sawn Face
Expressed in linear feet.
2,000 linear feet

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