Western Red Cedar Timber Guide

At Modinex, we’re experts in Western Red Cedar. We wanted to impart some of that knowledge with our customers to help make your decision in choosing the right timber a little bit easier. Below you’ll find benefits, technical information and FAQs that cover just about everything you would need to know about Western Red Cedar; from tree, to lumber, to timber, to cladding and more.

Western Red Cedar Benefits

More than just good looks. Western Red Cedar is one of the world’s most unique softwood species, renowned for its natural beauty and durability. Our range of innovative profiles offers unbeatable style, streamlined simplicity and incredible functionality.

Western Red Cedar Group Rating

For commercial interiors, Western Red Cedar achieves a Product Group Number Classification of 3.

Western Red Cedar is suitable for commercial interiors, especially when coupled with added protection from sprinklers. Externally, other materials can be utilised to achieve Bushfire Attack Level of 12.5, enabling the use of WRC above the area of concern.

Fire Test Certificate
Fire Test Report

Western Red Cedar Acoustic Properties

Cedar Sales offers a range of ceiling and wall designs that are engineer-approved to meet various acoustic ratings. Western Red Cedar’s open cellular structure helps to absorb and dissipate sound energy, making it effective in confining noise.

In external applications, Western Red Cedar’s sound deflection capabilities can be improved by adding a metal resilient rail. The use of thicker cladding profiles is also recommended.

For specialist uses, such as music rooms and auditoriums, we offer innovative panelling systems with enhanced sound deflection properties.

Unrivalled Sustainability

Western Red Cedar has long been acknowledged as the ultimate sustainable building product. At Cedar Sales, we are committed to delivering on sustainability. This commitment is reflected in our approach to product sourcing. We only purchase legally-harvested timber, with PEFC™ Certification. We source timber from newly-planted forests that provide additional carbon sinks and new animal habitats, as well as drawing on old growth for its superior durability.

Thermal Protection

When it comes to thermal insulation, Western Red Cedar is both practical and eco-friendly. Its low density makes it the best insulator of any available softwood, also outperforming brick, concrete and steel. When used as exterior cladding, Western Red Cedar keeps buildings cooler in summer,
while cutting heating costs in winter. This results in reduced energy usage and contributes towards a higher Green Star building rating.

Western Red Cedar’s thermal properties include:

  • A thermal conductivity factor K of 0.74 BTU in / ft2 h F.
  • An R-value of 1.35 per 25mm of thickness.

Structure & Performance

Western Red Cedar offers outstanding dimensional stability. With an Australian Durability Rating of 2, Western Red Cedar offers twice the stability of most commonly available conifers. Western Red Cedar is resistant to cupping, warping and shrinking, even when milled into intricate profiles. This highly-practical species offers exceptional durability, even without the use of coating. The naturally-occurring preservatives present in Western Red Cedar provide in-built resistance to termites, moisture and decay.

Western Red Cedar Technical Information

Western Red Cedar (Thuja plicata)

Western Red Cedar is a large softwood that grows in British Columbia and some of the nearby western states of the USA. A versatile timber, it is commonly used for applications such as cladding, windows and joinery. Renowned for its natural beauty and durability. This exceptional wood has rich tones ranging from mellow ambers, to reddish cinnamons and sienna browns. Its texture is uniform and fine-grained, with a satin lustre. Western Red Cedar is an incredibly durable timber that’s perfect for the outdoors. The heartwood contains extractives (called Thujaplicans and Phenolics), that are toxic to decay-causing fungi. Its superior resistance to warping, cupping and twisting makes it ideal for use in cladding, panelling and screening.

Physical Properties

  • Dry Density: 350 kg/m³
  • Janka Dry Hardness: 1.5 kN

The Janka rating is the hardness level given to each species. The higher the number, the greater the hardness.

Colour Range pale brown/cream or honey colour to rich dark brown
Janka (Hardness) Rating – Dry 1.5
Natural Durability Class In-ground contact 3
Outside above ground contact 2
Density (kg/m3) Unseasoned (Green)
Seasoned (Dry) 350
Strength Group Unseasoned (Green) S7
Seasoned (Dry) SD8
Joint Group Unseasoned (Green)
Seasoned (Dry) JD6
Fire Indices Spread-of-Flame Index 10
Smoke-Developed Index 4
Critical Radiant Flux
Smoke Development Rate <250
Group Number 3
Naturally bushfire-resisting Timber Unknown
Tangential Shrinkage % 3.0
Toughness (Nm) Naturally Unseasoned (Green) 15
Seasoned (Dried) 15
Naturally Termite Resistant to AS3660R = Resistant

NR = Non resistant

Naturally Lyctus SusceptibleS = Susceptible

NS = Non susceptible


Western Red Cedar FAQS

What Is Western Red Cedar?

Western Red Cedar (Thuja plicata) is an evergreen coniferous tree from the Cupressaceae family. It is a softwood, commonly used in both structural and aesthetic building projects. Originally native to North America, it is now grown all over the world, and a popular timber for use in architectural projects.

What Is Western Red Cedar Used For?

There are a plethora of uses for this softwood. From timber cladding and screening, to construction and decking. The wood is know to be easy to work with, machine well and stand the test of time.

What Does Western Red Cedar Look Like?

As a tree, Western Red Cedar is a conical / pyramidal shape, often very tall (growing up to 65m) with a dark reddish-brown, deeply textured bark. The canopy is often very dense, and the leaves look somewhat fern-like. Once the tree is cut, the timber has a range of colours, from pale brown to deep, dark reddish tones.

Is Western Red Cedar Sustainable?

Western Red Cedar is widely recognised as the ultimate sustainable timber. It produces fewer greenhouse gases, generates less water and air pollution and requires less energy to produce than alternatives. The Timber used at Cedar Sales comes from a renewable and sustainable resource.

What Colour Is Western Red Cedar?

As a tree, Western Red Cedar has a dark reddish-brown bark. Once milled for lumber, the timber is between a pale brown and rich darker brown colour. Sapwood tends to be lighter in colour, more of a yellow-brown. By staining, painting or other methods of finishing the timber you can get many different colours and gradients.

Does Western Red Cedar Fade?

When left exposed and untreated, the timber will quickly fade to a silvery-grey colour. For many, this is a very desirable look, especially in cladding, and will leave it exposed purposely for an older-look finish.

Does Western Red Cedar Turn Grey?

When untreated and left in the sun and to the elements, Western Red Cedar will fade to a silver grey colour. Very desirable for some. Avoid the greying by finishing the timber immediately.

Is Western Red Cedar A Hardwood?

No. Western Red Cedar is a softwood. Despite commonly thought of as weaker, many softwoods are in fact as strong as, if not stronger than, some hardwoods. Western Red Cedar is a very durable example of a softwood, and excellent for use in various architectural projects.

Is Western Red Cedar Waterproof?

Although not completely waterproof, the timber does have natural moisture-resisting properties. Left out in the rain and exposed to the elements, WRC will stand the test of time. To extend the life of your Cedar even further, be sure to finish it with your chosen oil, stain or paint.

Does Western Red Cedar Rot?

As with all wood, Wester Red Cedar will eventually rot if not cared for properly, however if the timber is fairly fresh, it will last a long time, even untreated, before it will begin to rot beyond repair. It is rated highly in terms of rot-resistance.

How Long Will Western Red Cedar Last?

Western Red Cedar is a very hardy timber, and will last a long time, even untreated. There are many factors to the lifespan of the timber;

  • Where it has been installed
  • Which direction the timber is facing (with regards to the sun)
  • How much time it will spend wet
  • Quality of the installation
  • Various treatment methods
  • Exposure to weather and more

Why Is Western Red Cedar Good Outdoors?

Western Red Cedar has many desirable properties which make it great for outdoor use. It has a natural resistance to moisture, rot and insects, and has been known to last a very long time when maintained correctly.

What Does Western Red Cedar Weigh?

The average dried weight of Western Red Cedar is around 370kg/m3, one of the lighter species of timber. Compared with Red Oak, which weighs around 730kg/m3, WRC is around half the weight of this hardwood.

Weight is calculated on averages at between 8%-12% moisture content.

How Does Western Red Cedar Age?

Western Red Cedar will grey overtime if not treated and maintained. For some, this is a very desirable quality, and will leave it to naturally age and weather. In some instances, the timber can develop dark, non-uniform patches and look, to some, very unsightly. Treating and maintenance will prevent non-uniform weathering or discolouration.

How Dense Is Western Red Cedar?

The desity of Western Red Cedar is 22 lbs/ft3

Western Red cedar is one of the lightest softwoods available. In it’s early stages it has a very low density growth; these low density areas of the wood contain small pockets of air, which are very useful for insulation.

Still Have Questions About Western Red Cedar?

No problem. We’d be happy to answer any more questions you have – please feel free to send us an email or give us a call. Our friendly team are on hand to help you out and get all the knowledge you need to help complete your next Western Red Cedar project.

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