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Western Red Cedar grows in coastal forests from British Columbia Canada, to California, along rugged mountains. It is a wood of exceptional beauty with warm mellow tones ranging from light amber to deep honey brown. It also has an aromatic fragrance unlike any other species.
Western Red Cedar contains natural oils that act as preservatives to help the wood resist insect attack and decay. It is not uncommon for Western Red Cedar furniture to last 30-40 years with minimal maintenance. Cedar is also a stable wood that lies flat and stays straight.
Cedar, a lightweight wood, makes it easy to handle, and can be cut, shaped, and accepts screws easily.
Without any sticky sap, Western Red Cedar is praised by mothers everywhere who know how hard it is to get out of clothing.
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Western Red Cedar Cross Section
Because of regional differences in soil and climate conditions, Western Red Cedar can have varying characteristics. This is important to know when choosing products made from Western Red Cedar. The large old-growth trees found in British Columbia yield clear heart-wood, which is used to make clear bevel siding - the most prized, (and the most costly), Cedar product. But, these trees also have a high amount of shake, rot, splits and large knots. Young-growth Cedar, found mostly in Washington State, has less clear heart-wood, but contains more material suitable for tight knot sidings. It has a lighter, more uniform color than old-growth Cedar and its knots are small and intergrown with the surrounding wood. Young-growth cedar has the added advantage of being renewable.
Western Red Cedar is one of North America's great renewable resources. Slow growing and naturally durable, Western Red Cedar has one of the longest lifespans of any North American softwood. It produces long lengths of timber with true, straight grain. It is free from pitch and its heartwood has natural decay resistance. Its low density gives it an insulation value superior to most other species. Light weight, easy to work, easy to finish, possessing outstanding dimensional stability, Western Red Cedar is a preferred wood for nearly all purposes where attractive appearance or resistance to weather is important.
Features of Western Red Cedar
Acoustic properties: Cedar tends to dampen sound transmission
Density (12% mc): 23 lb/ft3
Specific gravity (12% mc): 0.34
Durability: Durable species
Finishing: Paints, stains, varnishes, oils and waxes all work well
Flame spread rating: 69 (Class II)
Smoke developed classification: 98
k value (12% mc): 0.74 BTU in/ft2 hｰF
R value: Nominal lumber thickness/k value
Stability: Cedar is the most stable softwood species
Workability: Easy to cut, saw, nail and glue.
Physical Properties
Density
One of the lightest commercial softwoods, the density of Western Red Cedar at 12% moisture content is approximately 23 pounds per cubic foot with a relative density (specific gravity) of 0.34. The density of oven-dry material is 21 pounds per cubic foot.
Dimensional Stability
Like all woods, Western Red Cedar is hygroscopic and will absorb or discharge moisture to attain equilibrium with the surrounding atmosphere. However, it has a very low shrinkage factor and is superior to all other coniferous woods in its resistance to warping, twisting and checking.
Thermal Conductivity
Wood is an excellent thermal insulator. This is an important characteristic since good thermal insulators help keep buildings cool in the summer and reduce heating costs in winter.
The conduction of heat in wood is directly related to its density. Woods with low density have the highest thermal insulating value because such woods contain a high proportion of cell cavities. In dry wood, these cavities are filled with air which is one of the best known thermal insulators.
With its low density and high proportion of air spaces, Western Red Cedar is the best thermal insulator among the commonly available softwood species and is far superior to brick, concrete and steel. It has a coefficient of thermal conductivity (k value) at 12% mc of 0.74 BTU in./ft2h ｰF.
Acoustical Properties
An important acoustical property of wood is its ability to damp vibrations. Wood has a cellular network of minute interlocking pores which converts sound energy into heat by frictional and viscoelastic resistance.
Because of the high internal friction created by the cellular pore network, wood has more sound damping capacity than most structural materials. Floor, ceiling and wall assemblies of wood can provide effective economical sound insulation and absorption when properly utilized. Western Red Cedar is particularly effective in this regard and can be used to help reduce noise to confine it to certain areas.
Flame Spread Rating
Flame spread ratings describe the surface burning characteristic of interior finishes. They are used to regulate the use of interior finish materials to reduce the probability of rapid fire spread. Materials are burned in a test furnace for a relative assessment of flammability. The lower the flame spread rating, the more the material resists the spread of fire.
Building codes in North America generally define as interior finish any exposed material that forms part of the building interior. This usually includes interior wall and ceiling finishes, flooring, windows, doors and other wood products. U.S. codes set the maximum flame spread for interior wall and ceiling finishes in most buildings at 200. The flame spread rating for Western Red Cedar is 69 (Class II rating).
Smoke developed classifications reflect the amount of smoke released by a burning material. They are used in conjunction with flame spread ratings to regulate the use of interior finish materials where the potential to generate smoke or control smoke movement is of major fire safety importance.
U.S. codes set the maximum smoke developed classification for interior wall and ceiling finishes in most buildings at 450. The smoke developed classification for Western Red Cedar is 98.
Western Red Cedar's flame spread rating and smoke developed classification compare well with the ratings of many other species, both softwood and hardwood. Because of its favorable fire performance, Western Red Cedar can be used for interior finishes in some building applications where other species would not be permitted.
Durability
Historically, native peoples of the Pacific coast prized cedar for its long lasting qualities and used wood and bark from cedar trees for most of their building needs. Evidence of cedar's durability are the many cedar artifacts still in good condition today.
Properly finished and maintained, cedar will deliver decades of trouble-free service. If exposed for prolonged periods to conditions where decay could be a factor, such as where the wood is in contact with the ground, cedar should be treated with suitable wood preservatives.
Fastening
Western Red Cedar has good fastening properties. Nails and screws used to fasten Western Red Cedar should be about one-third longer than those used to fasten hardwood species.
Because it is free of pitch and resin, Western Red Cedar has excellent gluing properties, comparable to those, for example, of old growth Redwood and American Chestnut. It works well with a wide range of adhesives.
Finishing
Although cedar is a naturally durable species, leaving it untreated is not recommended because a finish or protective coating will greatly increase its service life. Cedar is free of pitch and with its high degree of dimensional stability, it is the best of the softwoods for accepting paints, stains, oils and other coatings. For further details, see General Information on Finishing Western Red Cedar.
Workability
With its straight grain and uniform texture, Western Red Cedar is among the easiest and most rewarding woods to work with. It takes a fine finish in all hand and machine operations, takes fasteners without splitting and is easily sawn and nailed. When working with Western Red Cedar, sharp cutters are recommended.
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