Northern white-cedar and Atlantic white-cedar: Decay & insect resistant
July 21, 2022 | 1:25 pm CDT
Wood explorer

Pictured is northern white-cedar.

There are two separate tree species that are called white-cedar. Northern white-cedar (Thuja occidentalis), also called arborvitae or just cedar (there are over 40 local names), grows in Quebec to Maine to New York and westward to Minnesota as well as down the Appalachian Mountains from Pennsylvania to Tennessee. Atlantic white-cedar (Chamaecyparis thyoides), also called southern white-cedar and boat cedar, grows in swamps in the coastal regions from Maine to Florida. Northern white-cedar lumber is manufactured primarily in the Lake States; Atlantic white-cedar in the Carolinas and Gulf States.

The two separate species are not closely related, but sometimes are grouped together, as the properties are almost identical. The lumber is highly resistant to decay and insects. The surface is fairly soft, and the strength, overall, is fairly low, compared to other North American species.

In the past, these two species were used for tight cooperage, boat building, fences and tableware. Northern white-cedar is often used for log cabin logs today; Atlantic white cedar is used for furniture. White cedar is one of the primordial trees the Ojibway honored with the name Nokomis Giizhig, Grandmother Cedar. Native Americans used the leaves and twigs to treat malaria, coughs, gout, and rheumatism. This purported medical benefit is most likely the origin of the term arborvitae (tree of life).

Processing suggestions and characteristics

Density. The density at 9% MC is approximately 20 pounds per cubic foot. A board foot of 4/4 dried (9% MC) and planed lumber (3/4” thick) will weigh only about 1-1/4 pounds.  This is the lightest weight native American species.

Drying. The wood is very easy to dry without many defects. However, if dried under 9% MC or dried at over 180 F, the wood will become quite brittle. In practice, this wood is often, inadvertently, over-dried. Shrinkage in drying is 3% maximum-a very low shrinkage value.

Machining and gluing. This is one of the easiest woods to glue and is quite forgiving if gluing parameters are not perfect.  Machining is very good, although the softness of the wood means that machine pressures must not be excessive. When these cedars will be used for fine woodworking, it is critical to avoid over-drying.

Strength. The ultimate strength (MOR) is 6500 psi, the elasticity (MOE) is 800,000 psi, and the hardness is 320 pounds. Screw, staple and nail holding are quite low.

Stability. The wood is extremely stable. It takes over 6% MC change to result in a 1% size change in the tangential direction (the width of a flatsawn piece of lumber) and a 12% MC change in the radial direction.

Grain and color. The wood color is light brown, perhaps with a little reddish color. There is a distinctive spicy odor and a bitter taste. The grain is very even and fine, with a little oily feel at times. This is a good utility wood and would be a top choice for outdoor furniture, as well as many indoor uses.

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About the author
Gene Wengert

Gene Wengert, “The Wood Doctor” has been training people in efficient use of wood for 35 years. He is extension specialist emeritus at the University of Wisconsin-Madison.