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Western red cedar

Scientific name

Thuja plicata. Family: Cupressaceae

Other names

British Columbia cedar; western cedar; red cedar

Description

  • Large tree grows to 40–55m high and 1–3m in stem diameter.
  • Specimens have been recorded at more than 65m high and 5m in stem diameter.
  • Typical long tapering form of a North American conifer.
  • Bark is relatively thin for such a large tree.
  • Fibrous and fissured.

Occurrence

  • Natural distribution:
    • British Columbia
    • Canada
    • United States—Washington, Oregon, Idaho and Montana.
  • Readily available as imported timber.

Appearance

Colour

  • Heartwood is pale brown to dark brown.
  • Sapwood is yellowish white and up to 25mm wide.

Grain

  • Fine texture and straight grain with distinct growth rings.

Uses

  • Construction: sawn timber in cladding, linings, joinery and shingles.
  • Decorative: indoor and outdoor furniture, turnery, joinery, carving.
  • Others: beehives, venetian blinds, roller blinds, light boat building.

Properties

  • Density: 380kg/m3 at 12% moisture content; about 2.6m3 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 according to AS 2858—2008 : 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 15–40 years).
  • Durability in-ground: Class 2 (life expectancy 15–25 years).
  • Lyctine susceptibility: sapwood not susceptible to lyctine borer attack.
  • Termite resistance: resistant.
  • Preservation: rarely enough sapwood to warrant preservation; penetration of heartwood by preservatives is negligible using available commercial processes.
  • Seasoning: satisfactorily dries using conventional air and kiln seasoning.
  • Hardness: very soft (rated 6 on a 6-class scale) to indent and work with hand tools.
  • Machining: machines, and turns well, to a smooth surface.
  • Fixing: ferrous fastenings and fittings may be corroded by wood extractives if exposed to the weather.
  • Gluing: satisfactorily bonds using standard procedures.
  • Finishing: readily accepts paint, stain and polish.

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 grain.

Wood structure

  • Growth rings: distinct, visible without a lens; abrupt latewood to earlywood transition; latewood bands are much narrower than earlywood bands.
  • Vessels: absent.
  • Parenchyma (soft tissue): not visible with a hand lens.
  • Rays: fine, visible only with a hand lens.

Other features

  • Burning splinter test: match-size splinter burns completely to a grey-black, fine filament.
  • Odour: characteristic sweet and fragrant cedar.

Research and resources

  • Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, Forest trees of Australia, 5th ed., CSIRO Publishing, Collingwood, Australia.
  • Bootle, K 2005, Wood in Australia: Types, properties and uses, 2nd ed., McGraw-Hill, Sydney.
  • Ilic, J 1991, CSIRO atlas of hardwoods, Crawford House Press, Bathurst, Australia.
  • Queensland Government, DAF 2018, Construction timbers in Queensland: Properties and specifications for satisfactory performance of construction timbers in Queensland. Class 1 and Class 10 buildings, Books 1 & 2, Department of Agriculture and Fisheries, Brisbane.
  • Standards Australia, 2008, AS 2082—2008: Timber—Softwood—Visually stress-graded for structural purposes, Standards Australia International, Strathfield, NSW.