Cedar
Cedar is a naturally decay-resistant softwood prized for its distinctive aroma, beautiful color variations, and exceptional durability in exterior applications, making it an ideal choice for siding, decking, outdoor structures, and other applications where resistance to moisture, insects, and decay is essential.
Composition
Cedar is a natural softwood primarily from the Cedrus and Thuja genera. The most commonly used species in construction are Western Red Cedar (Thuja plicata), Eastern Red Cedar (Juniperus virginiana), Northern White Cedar (Thuja occidentalis), and Spanish Cedar (Cedrela odorata). Cedar contains natural oils, primarily thujaplycins and other extractives, that give the wood its distinctive aroma and contribute to its natural decay and insect resistance. These oils can comprise 2-3% of the wood's weight in Western Red Cedar. Cedar typically has a moisture content of 12-15% when kiln-dried for construction applications.
Properties
Density
22-31 lbs/ft³ (350-500 kg/m³)
Relatively low density compared to many other woods, with Western Red Cedar being among the lightest commercial softwoods at 22-25 lbs/ft³. This low density contributes to cedar's excellent insulating properties and makes it easy to work with and transport.
Janka Hardness
320-900 lbf (varies by species)
Western Red Cedar is quite soft (320 lbf) while Spanish Cedar is harder (900 lbf). Cedar's relatively low hardness makes it easy to work with but more susceptible to dents and scratches than harder woods.
Decay Resistance
High to Very High
Exceptional natural resistance to decay and insects due to the presence of natural oils and extractives. Western Red Cedar heartwood is rated as highly durable, capable of lasting 25+ years in ground contact without treatment, though sapwood has less resistance.
Dimensional Stability
Excellent
Cedar has among the best dimensional stability of any wood species, with minimal movement in response to humidity changes. This makes it ideal for applications where warping, cupping, or twisting would be problematic.
Thermal Conductivity
0.7-0.8 BTU·in/h·ft²·°F (0.10-0.12 W/m·K)
Cedar's cellular structure and low density give it excellent insulating properties, with thermal conductivity approximately 80% better than most hardwoods and significantly better than concrete, brick, or steel.
Grain Pattern
Straight grain with subtle texture
Cedar typically has a straight, even grain pattern with a fine to medium texture. The wood features a subtle but distinctive grain pattern with visible annual rings. Color varies from light amber to deep reddish-brown, often with attractive streaking.
Applications
Exterior Siding and Shingles
One of the premier materials for exterior cladding due to its natural decay resistance, dimensional stability, and aesthetic appeal. Cedar siding is available in various profiles including bevel, tongue and groove, board and batten, and shingles/shakes. Western Red Cedar is particularly valued for this application, with its low density providing excellent insulation and its natural oils ensuring longevity. Cedar siding can be left unfinished to weather naturally to a silver-gray patina or finished with stains or oils to maintain its original color.
Decking and Outdoor Structures
Widely used for decks, pergolas, arbors, gazebos, and other outdoor structures where decay resistance is critical. Cedar decking remains cool underfoot in summer due to its low thermal conductivity and resists checking (splitting) better than many alternatives. It is naturally resistant to the fungi that cause wood rot and to many insects including termites. Cedar is also used for outdoor furniture, planters, and landscape elements where its natural durability and attractive appearance are valued.
Fence Posts and Rails
Ideal for fencing applications due to its natural decay resistance and dimensional stability. Western Red Cedar and Northern White Cedar are particularly valued for fence posts, rails, and pickets. Cedar fencing can be left natural to weather to a silver-gray or finished to maintain its original color. Its resistance to warping and twisting helps fences maintain their appearance and structural integrity over time.
Interior Paneling and Accent Walls
Used for interior wall paneling, ceiling treatments, and accent walls where its aromatic properties, warm appearance, and insulating qualities are desired. Cedar's natural oils provide a pleasant scent that can last for years. Common profiles include tongue and groove, beadboard, and shiplap. Cedar paneling is particularly popular in spaces where a natural, warm aesthetic is desired, such as cabins, lodges, and rustic-themed rooms.
Closet Lining and Storage Chests
Traditionally used to line closets, chests, and storage spaces due to its aromatic properties that naturally repel moths and other insects. Eastern Red Cedar (aromatic cedar) is particularly valued for this application due to its stronger scent. Cedar closet lining helps protect clothing and other stored items from insect damage while imparting a pleasant fragrance.
Saunas and Hot Tubs
The preferred material for sauna construction and hot tub surrounds due to its resistance to moisture, low thermal conductivity, and pleasant aroma when heated. Cedar's low density means it doesn't get as hot to the touch as denser woods, making it comfortable for seating. Its natural oils help it withstand the high humidity environment without decay, and it contains no pitch or resin that might be released by heat.
Advantages
- Exceptional natural resistance to decay, rot, and insects
- Excellent dimensional stability with minimal warping or checking
- Superior thermal insulation compared to most building materials
- Naturally resistant to moisture and humidity fluctuations
- Pleasant aromatic properties that can last for years
- Beautiful appearance with rich color variations
- Lightweight and easy to work with using standard tools
- Can be left unfinished for low maintenance applications
Limitations
- Softer than many woods, making it susceptible to dents and scratches
- Higher cost than pine and some other softwoods
- Natural oils can interfere with some paints and finishes
- Color fades to silver-gray if left untreated outdoors
- Limited structural applications due to lower strength compared to some alternatives
- Sustainability concerns with old-growth Western Red Cedar
- Can be difficult to glue due to natural oils
- Requires careful selection of fasteners to prevent staining
Sustainability Profile
Cedar has a mixed sustainability profile that varies by species and source. Western Red Cedar, the most commonly used cedar in construction, grows relatively slowly (50-75 years to harvest maturity) and old-growth forests have been significantly reduced. However, second-growth forests and sustainable forestry practices are increasingly common. Look for FSC or SFI certification to ensure responsible harvesting. Cedar's exceptional durability and longevity significantly improve its lifecycle assessment, as products can last decades without chemical treatment, reducing replacement frequency and associated environmental impacts. Cedar requires less energy to process than many manufactured alternatives and doesn't require chemical preservatives that might have environmental impacts. At end of life, cedar is biodegradable and can be recycled, repurposed, or used as biomass fuel. Cedar forests provide important ecosystem services including carbon sequestration, wildlife habitat, and watershed protection. The natural decay resistance of cedar eliminates the need for chemical preservatives that might leach into the environment, making it an environmentally friendly choice for many exterior applications.