General Materials

Sizes of Western Red Cedar

Sizes of Western Red Cedar timbers and dimensional products are typically available in a wide selection of thicknesses from 1” to 12” and widths from 2” to 12”. Consult your supplier to determine which sizes are available before you begin your project. Standard lengths are in multiples of two feet, typically up to 16’. Longer lengths and sizes may be available on a special order basis.

Table 1. Sizes of Rough (sawn) Western Red Cedar

1 2 3 4 6 8 10 12 14
2 4 6 8 10 12 14

Table 2. Sizes of Dressed (smooth) Western Red Cedar

Item Thickness (inches) Width (inches)
  Nominal Actual Nominal Actual
Dry Green   Dry Green
Boards 1 11/16 3/4 2 1-9/16
7/8 3 2-9/16
1 1-1/32 4 3-9/16
6 5-9/16
8 7-3/8
10 9-3/8
12 11¼ 11-3/8
Garden Lumber 2 1-9/16 2 1-9/16
3 2-9/16
3 2-9/16 4 3-9/16
6 5-9/16
4 3-9/16 8 7-3/8
10 9-3/8
12 11¼ 11-3/8
Timbers 5 5
6 6
8 8


*Surfaced timbers 5″ and larger available only on special order. Confirm before specifying.

Spans for Western Red Cedar

Spans for Western Red Cedar dimension lumber used as joists and rafters in residential and commercial structures are available from the Western Red Cedar Lumber Association, the Canadian Wood Council and the National Association of Home Builders. Other references: The Cdn Span Book or U.S Span Book for Canadian Lumber.

Maximum Span Calculator for Wood Joists & Rafters performs calculations for ALL species and grades of commercially available softwood and hardwood lumber as found in the NDS 2005 supplement. Joists and rafter spans for common loading conditions can be determined. A “span options” calculator allows selection of multiple species and grades for comparison purposes.

Note: Confirm load requirements with local codes. Refer to Model Building Codes or the National Design Specification for high-temperature or fire-retardant treated adjustment factors.

Grades of Western Red Cedar

Clear grades of Western Red Cedar have a limited number of natural characteristics and is specified when appearance of the highest quality is desired. Clear grades are normally supplied green (unseasoned).  When required, seasoning is achieved by air-drying.  Kiln dried products are available on a custom order basis.

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. Kiln dried knotty Western Red Cedar products are also available upon request.  Assure yourself of quality Western Red Cedar, purchase products from suppliers associated with the Western Red Cedar Lumber Association.

Surface Textures of Western Red Cedar

Western Red Cedar products may be specified in different surface finishes.

  • Rough – band sawn – textured on all four sides
  • Rougher Headed – texture planed with textured planer knives on all four sides
  • S1S2E – smooth planed surface on 1 face and 2 edges; band sawn surface on other face
  • S4S – smooth planed surface on 4 sides

Fasteners for Western Red Cedar

Hot-dipped galvanized, aluminum and stainless steel fasteners are all corrosion-resistant and can be used to fasten Western Red Cedar. Other types of nails or screws are not recommended. They can rust and disintegrate and react adversely with the natural preservative oils present in cedar resulting in unsightly stains and streaks. Brown Ceramic coated zinc fasteners are a viable option in dry climates.  Stainless steel fasteners are the best choice, especially if the wood is to be finished.  Use No. 304 stainless steel for general applications and No. 316 for seacoast exposure.

Finishing of Western Red Cedar

The choice to finish your Western Red Cedar project is yours. You can allow your Western Red Cedar to weather naturally or, with the application of a protective coating that will ensure maximum performance; you can retain the natural beauty of the wood or, change it up by using coatings in a wide array of colors.

A simple treatment helps the wood achieve a uniform, naturally aged patina.   Alternately, Western Red Cedar accepts a wide range of stains and paints.  When selecting a finish coat, make sure it contains the following: water repellent; fungicide / mildewcide; protection against ultra violet (UV) light.  Penetrating oil-based products, particularly those containing pigments, are recommended for Western Red Cedar.  Pigments provide increased UV protection.  Semi-transparent stains can be used for decks, landscape structures, fences, siding and trim. Solid stains and paint can be used for siding, trim, landscape structures and fences but never decks. Use an Alkyd Oil base and Stain Blocking Primer, not shellac based. Top Coats should always be 100% Acrylic stain or paint.

Note that decks require products specifically formulated to withstand the abrasive effects of foot traffic. Use of varnishes, paints and other types of film forming coatings are not recommended for cedar decks.

Before You Start:

  • If you plan to finish your Western Red Cedar do so ASAP (within days).  To obtain a premium bond, do not allow the surface to weather before applying the finish coating.
  • Prime all surfaces before applying paint or solid stains with a ‘Stain Blocking’ primer designed for use with Western Red Cedar.
  • Finish Western Red Cedar on all surfaces.
  • Coat the cut ends during installation.

New Cedar performs best when ‘Machine Stained or Factory Primed’ on all 6 sides of every piece. Use a brush or a ‘pad painter with bristles rather than a roller; if you spray coat, brush it in.  For more detailed information on finishing, order the WRCLA’s “Guide to Finishing” or visit the website.