Western red cedar

Scientific name

Thuja plicata. Family: Cupressaceae.

Local names

British Columbia cedar, western cedar, red cedar.

Description and natural occurrence

A large tree attaining a height of 40 to 55 m and 1 to 3 m in stem diameter. Specimens have been recorded at over 65 m and 5 m in stem diameter.

Western red cedar occurs in British Columbia, Canada and in the United States of America in Washington, Oregon, Idaho and Montana. It has the typical long tapering form of a North American conifer.

The bark is relatively thin for such a large tree. It is fibrous and fissured.

The timber is readily available from imported timber sources.

Wood appearance

Colour. Heartwood varies from pale brown to dark brown. Sapwood is yellowish white and up to 25 mm wide.

Grain. Fine textured and straight grained with distinct growth rings.

Wood properties

Density. 380 kg/m3 at 12% moisture content; approximately 2.6 m3 of seasoned sawn timber per tonne.

Strength groups. S<7 unseasoned; SD8 seasoned.

Stress grades. F4, F5, F7, (unseasoned), F4, F5, F7, F8 (seasoned), when visually stress graded in accordance with AS 2858-2001, Timber - softwood - visually graded for structural purposes.

Joint groups. JD5 seasoned.

Shrinkage to 12% MC. 3.0% (tangential); 1.5% (radial).

Unit shrinkage. Not available.

Durability above ground. Class 2 - life expectancy 15 to 40 years.

Durability in-ground. Class 2 - life expectancy 15 to 25 years.

Lyctine susceptibility. Sapwood not susceptible to lyctine borer attack.

Termite resistance. Resistant.

Preservation. Sapwood is rarely present in sufficient quantities to warrant preservation. Penetration of heartwood by preservatives is negligible using currently available commercial processes.

Seasoning. Can be satisfactorily dried using conventional air and kiln seasoning methods.

Hardness. Very soft (rated 6 on a 6 class scale) in relation to indentation and ease of working with hand tools.

Machining. Machines and turns well to a smooth surface.

Fixing. Ferrous fastenings and fittings may be corroded by wood extractives when used in weather-exposed situations.

Gluing. Can be satisfactorily bonded using standard procedures.

Finishing. Readily accepts paint, stain and polish.

Uses

Construction. As sawn timber in cladding, linings, joinery and shingles.

Decorative. Indoor and outdoor furniture, turnery, joinery, carving.

Others. Beehives, venetian blinds, roller blinds, boat building (light).

Identification features

General characteristics

Sapwood. Yellowish-white, distinct from heartwood.

Heartwood. Pink brown to dull brown, often with darker brown streaks.

Texture. Fine with typical earlywood/latewood bands. Straight grained.

Wood structure

Growth rings. Distinct, visible without a lens. Latewood to earlywood transition abrupt. Latewood bands much narrower than earlywood bands.

Vessels. Absent.

Parenchyma. Not visible with a hand lens.

Rays. Fine, visible only with a hand lens.

Other features

Burning splinter test. A match size splinter burns completely to a grey-black fine filament.

Odour. The wood has a characteristic sweet and fragrant cedar odour.

Further reading

Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, 'Forest trees of Australia', 5th edn, CSIRO Publishing, Collingwood Australia.

Bootle, K 2005, 'Wood in Australia: types, properties and uses', 2nd edn, McGraw-Hill, Sydney.

Hopewell, G (ed.) 2006, 'Construction timbers in Queensland: properties and specifications for satisfactory performance of construction timbers in Queensland, Class 1 and Class 10 buildings', books 1 and 2, Department of Primary Industries and Fisheries, Brisbane.

Ilic, J 1991, 'CSIRO atlas of hardwoods', Crawford House Press, Bathurst, Australia.

Standards Australia, 2000, 'AS 2082-2000: Timber - hardwood - visually stress-graded for structural purposes', Standards Australia.

Last updated 17 August 2010