Western red cedar

Category: Softwood
Region: Coast, Interior
Title: Western red cedar (Thuja plicata)

Western red cedar is a resilient and versatile species that can be used in a wide variety of exterior and interior building applications. It is one of the most valuable conifers owing to the unique colour, texture and durability of its wood.

It grows at low to mid elevations along the BC coast and in wetter parts of the southern interior. It holds great spiritual significance for Indigenous peoples along the northwest Pacific Coast. BC is the only province that western red cedar grows. The beauty and dimensional stability of its wood make it an important commercial species.

Where it grows

Western red cedar is shade tolerant and grows in areas where the climate is cool, mild and moist, including low- to mid-level elevations along BC’s coast and in the interior wet belt near the Columbia and Rocky Mountains.

It is found in uneven-aged, mixed-species stands with Douglas-fir, Sitka spruce, western hemlock, black cottonwood and red alder, and it grows with Englemann spruce and western larch at higher elevations. Growing terrain is characterized by a lush layer of ferns, huckleberries and Devil’s club, with a thick carpet of mosses on the forest floor. Western red cedar has a shallow, wide-spreading and strong root system.

Did you know?

The western red cedar was adopted as BC’s official tree in 1988.

Identifiable characteristics

The western red cedar is a medium- to large-sized tree that grows up to 60 metres tall and 2.5 metres in diameter and often lives to 1,000 years. Its trunk tapers rapidly and it has a long, even crown that becomes irregular with age, often with a forked top. The bark is grey and stringy and tears off in long strips on mature trees. Leaves are scale-like, arranged on the twigs in flat, fan-like sprays that emit a distinctive aroma. Seed cones are egg-shaped with several pairs of scales that ripen in late summer and shed during winter. Pollen cones are small and reddish.

Did you know?

The wood of fallen western red cedar trees remains sound for more than 100 years because of its resistance to decay and insect damage. Even after 100 years, the wood can be salvaged and cut into shakes for roofs.

Common uses and applications

Western red cedar is naturally resistant to decay and insect damage, so no chemical treatment is required. Its superior durability, aesthetic beauty and dimensional stability make it an excellent choice for exterior applications in residential or commercial projects. It is used for roof shingles, exterior siding and cladding, decking, weather boarding, portable buildings, poles, posts and fences, and ship and boat building. It is a popular wood for outdoor uses such as greenways, public art, urban parks and landscape design, patio furniture, playground equipment, greenhouses, garden boxes, gazebos, sheds and pergolas.

Western red cedar is an attractive wood for interior applications including sashes, doors and windows, ceiling and wall panelling, and custom millwork. Its dimensional stability makes it perfectly suited for sauna panelling, mouldings and window blinds. It is a good choice for musical instruments due to its superb acoustic resonance properties.

Western red cedar holds important spiritual and cultural meaning for Indigenous peoples in BC, and they use it for medicines, essential oils, spiritual ceremonies and other cultural uses. Indigenous peoples use almost every part of a cedar tree. Roots are dried and braided to make hats and baskets. Withes are strong, lightweight and naturally grow in long strands so they are suitable for ropes and lashing. Bark is dyed and processed into thread for mats, clothing, blankets and hats. Bark is also used for ropes, baskets and fishing nets. Dried bark is an excellent tinder for matches and torches. Cedar wood is used for totem poles, carvings, masks and longhouses, as well as canoes, paddles, hooks, spears and fishing floats. Fish are preserved in cedar smokehouses or dried on cedar racks.

Western red cedar is also used by Indigenous people to make bentwood boxes to store food or other goods. The boxes are made from a single cedar plank which is steamed until pliable and then bent. The two sides are pegged together. The boxes are decorated with paint or carvings.

Four Host First Nations Pavilion, Vancouver
Photo credit: KK Law

Commercial properties

Western red cedar wood is fairly lightweight, moderately soft and low in strength. It is known for its excellent working properties and its ability to take a smooth, satiny finish with sharp tools. It is relatively easy to work, with good machining qualities. It planes and shapes well and can be sanded to a smooth finish. It glues easily, has moderate nail and screw holding ability, and takes a good finish.

Western red cedar produces thujaplicin, a defense mechanism against rot and fungus. This natural fungicide enables even a dead tree to be a valuable part of the forest. Properly finished, western red cedar products will last for decades, even in harsh environments.

Squamish Lil’Wat Cultural Centre
Photo credit: Michael Bednar

Commercial availability

While western red cedar can be graded structurally under National Lumber Grades Authority (NLGA) grade rules, it is more often graded for appearance and specialty applications such as clears, shop, fence, panelling and siding.

Western red cedar lumber is often sold green due to its unique properties and longer drying times. When dried, lumber is dried according to end-use and customer specifications. Kiln drying inhibits natural staining of the wood, improves its strength and stiffness, enhances its appearance, and increases its resistance to decay and attack by insects.

Western red cedar – physical properties

Density (kg/m3)Green330
Air dry339
Specific gravity (12% m.c.)Standard0.33
Hardness (N)Side1470
End3000
MOE (Mpa)Green7240
Air dry8270
MOR (Mpa)Green36.5
Air dry53.8
Compression parallel (Mpa)Air dry33.9
Compression perpendicular (Mpa)Air dry3.43
Shear (Mpa)Air dry5.58
Cleavage (N/mm width)Air dry25.4
ShrinkageRadial (OD)2.1%
OD = oven dryTangential (OD)4.5%
air = air dry 12%Volumetric (OD)7.8%
Volumetric (air)4.8%
Tang / rad ratio2.1

Western red cedar – visual properties

Colour
HeartwoodPinkish- or reddish-brown to dark chocolate-brown. On exposure to light, the colour becomes more uniform. Exposed to the weather, it assumes a pleasing silver-grey colour over time.
SapwoodStraw coloured.
Heartwood / sapwood contrastThe sapwood is narrow and distinct from heartwood.
Latewood / earlywood contrastThe annual growth rings are distinct, defined by narrow bands of latewood. Transition from earlywood to latewood is abrupt in narrow rings and gradual in fast-growing, wide-ringed wood.
Grain
The wood is generally straight-grained; has a uniform but medium coarse texture.
Figure
Plainsawn lumber or rotary-cut veneer: distinct, inconspicuous growth ring.
Quartersawn lumber or quarter-sliced veneer: faint growth ring stripe.
Other: Wood is non-resinous.
Knots
Medium to large knots.
Other
Wood of western red cedar is aromatic and is often described as sweet or chocolate-like.
Free from pitch and resin.

Western red cedar – working properties

ProcessPerformanceComments
Machining
PlaningModerate to goodRecommended planer settings: 20° hook and 20 kmpi (knife marks per inch). Wood is subject to compression during planing. Must use sharp cutting tools. Wood is somewhat brittle and splintering is common.
TurningMedium to low surface qualityCommon defects: torn out grain.
SawingEasy to work with toolsEasy to saw because of its low density. Corrosive properties can be damaging to cutting blades.
BoringGood to mediumGood boring quality with brad point bits and moderate quality with single twist bits.
MortisingModerateBetter mortising quality is found with a hollow chisel mortise.
ShapingGood shaping qualitySplintering on the end-grain may be an issue. Recommended: the use of a counter piece for end-grain shaping.
VeneeringN/A
SandingExcellent
Fastening
ScrewingLow to moderateAverage screw rentention: 308 lb.
Nail retention Low to moderateDue to the acidic properties of its extractives this wood tends to accelerate the corrosion of metals, particularly when in contact with unprotected ferrous metal. Hot-dipped galvanized nails are recommended. It is essential that stainless steel, brass, aluminium, copper or metals with a protective coating be used when applying fittings, fixtures or fasteners.
Lateral nail holdingN/A
GluingEasyBonds very easily with adhesives of a wide range of properties and under a wide range of bonding conditions.
Finishing
StainingEasyVery smooth texture achieved, but sometimes difficult to hide natural texture of wood. Very soft wood that loses some grain design as stain becomes darker. Some wild grain was present in Interior red cedar.
PaintingModerate to good paint holding ability
LacqueringGoodClear coats with little difficulty. A high build clear coat works best for the coastal wood while it was recommended for Interior red cedar to use a clear finish, nitrocellulose/ alkyd sealer and finish system. Performed well in the tape test (i.e. small flakes of the coating were detached along edges and at intersections of cuts) and in the pull-off test (i.e. average strength of 25 kg/cm2).
WaxingGoodGood results are obtained when using light-, medium- or dark-coloured waxes (e.g. mellow pine, chestnut or jacobean).
Drying
Ease of dryingModerately easy to moderately difficultThe drying of thin boards is generally easy with little degrade to occurring. As red cedar tends to hold its moisture at the centre, care is required when drying thicker stock as internal honey-combing and collapse are common defects. Longer drying times are required.
Durability
Natural decay resistanceDurableAppropriate for outdoor usage.
TreatabilityImpermeable to extremely impermeableCan be improved by incising.