Trim Boards

Trim Board Characteristics

Cedar Trim Board Around DoorWestern Red Cedar trim boards are available in a variety of grades and textures to complement the style you have envisioned. Clear boards have a limited number of natural characteristics and are specified when “clean”, fine appearance of the highest quality is desired. They are available kiln dried or unseasoned. Knotty boards present a more rustic appearance and may be specified seasoned or unseasoned. Texture options of rough, surfaced one side, two edges and surfaced on four sides further enhance your design flexibility.

Trim Board Grades

Kiln dried clear grades of western red cedar trim boards graded as finish lumber. Typically available as S4S or S1S2E products.

Clear Heart

Clear Heart Cedar Siding

The highest grade. Includes only pieces with heartwood on the exposed face. Many pieces completely clear, others have minor imperfections that do not detract from their fine appearance.

Grading Rule Paragraph

NLGA 200a
WCLIB 102-b
WWPA 20.11

A Clear

A Clear Cedar Siding

Permits somewhat more imperfections than Clear Heart but the grade is still restricted to pieces with excellent appearance.

Common specifications are A and Better and A and Better with a percentage of B Clear allowed (NLGA 200c/WCLIB 102-d/WWPA 20.13).

Grading Rule Paragraph

NLGA 200b
WCLIB 102-c
WWPA 20.12

C and Better Clear

C Clear or Better Cedar Siding

High quality lumber for use where appearance is important.In addition to interior and exterior trim, lumber of this grade is used for cabinetry, doors, windows and similar applications.

* Common specifications are C and Better and C and Better with a percentage of D Clear allowed.

Grading Rule Paragraph

NLGA 202b, 202c
WCLIB 149-b, 149-c
WWPA 10.11, 10.12

Select Knotty

Select Knotty Cedar Siding

Knots are sound and tight. Other characteristics are limited so they do not detract from the end use intended.

* Common specification is Select Knotty with a percentage of Quality Knotty allowed.

Grading Rule Paragraph

NLGA 204a
WCLIB 111-e


Proprietary Grade Cedar Siding

Graded to the manufacturer’s specifications to meet the intended end use. Boards often represent good value in the no-hole product range. Consult manufacturer’s for grade descriptions and nomenclature.

Grading Rule Paragraph

NLGA n/a

Standard and Better

Standard or Better Cedar Siding

Suitable for exterior construction. Occasional pieces may require trimming to yield suitable quality for the intended end use. Typically supplied as S1S2E products. S4S products may require special ordering.

Grading Rule Paragraph

NLGA 114a,b,c
WCLIB 118-a,b,c
WWPA 30,50 (118a, b, c)

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

Trim Board Sizes

Thickness (in.) Width (in.)
Nominal Actual Nominal Actual
Dry Green Dry Green
1 3/4 3/4 2 1-3/4 2
13/16 13/16 3 2-3/4 3
7/8 7/8 4 3-3/4 4
5/4 1-1/8 1-1/8 6 5-3/4 6
8 7-3/4 8
10 9-3/4 10
12 11-3/4 12
Surfaced One Side Two Edges (S1S2E)
1 11/16 11-16 2 1-1/2 1-9/16
7/8 3/4 3 2-1/2 2-9/16
13/16 4 3-1/2 3-9/16
7/8 6 5-1/2 5-9/16
5/4 1 1-1/32 8 7-1/4 7-3/8
2 1-1/2 1-1/2 10 9-1/4 9-3/8
12 11-1/4 11-3/8
Surfaced Four Sides (S4S)
1 11/16 3/4 2 1-1/2 1-9/16
7/8 3/4 3 2-1/2 2-9/16
13/16 4 3-1/2 3-9/16
7/8 6 5-1/2 5-9/16
5/4 1 1-1/32 8 7-1/4 7-3/8
2 1-1/2 1-9/16 10 9-1/4 9-3/8
12 11-1/4 11-3/8

Trim Board Textures

Western Red Cedar boards may be specified in one of three surface finishes: rough; surfaced one side, two edges (S1S2E); or surfaced four sides (S4S).

Rough Boards

The rough sawn texture from either circular or band saws is present on all four sides.

Surfaced One Side, Two Edges (S1S2E)

This versatile product is the most popular choice for trim boards. The surfacing process resulting in a rough sawn face and a smooth back provides uniform width and thickness tolerances. Typically graded from the rough face, it may in some instances be reversible to the smooth back.

Surfaced Four Sides (S4S or PAR, D4S)

The smooth surface on all four sides presents a uniformly sized product with a quality appearance. This surface finish is most commonly found on Clear grades.

Trim Board Specifications

Specification Information Required Sample Specification
Western Red Cedar
WRCLA Western Red Cedar
Product Pattern and Intended Use:
Trim boards are generally used in applications such as corner boards, fascia, skirting, and detail around windows and doors. Specify the surface finish by choosing surfaced four sides (S4S) surfaced one side and two edges (S1S2E), or rough sawn all round (rough).
S1S2E Boards
Specify the nominal size of the product.
1 x 6 in.
The grade of the product governs its overall quality. Refer to WRCLA specification literature or grading agency rule books for available grades.
Select Knotty
Grading Agency Paragraph:
To ensure that the product meets a written standard, an agency grade paragraph should be referenced.
NLGA para. 200a, b
Moisture Content:
Specify whether the product is to be green (unseasoned) or kiln-dried.
Surface to be exposed:
Specify the application orientation to assist the supplier in shipping the right product for the job.
Resawan face
Express in linear feet
2,000 linear feet
Please note that the measurements displayed on this webpage are displayed in Imperial units. If metric is required, please perform the proper conversion as necessary.
Please note that the standards, grades and other information mentioned on this webpage are based on North American data. Please refer to your local resources or authorities for country-specific data relating to a particular country if required.