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Teak

Scientific name

Tectona grandis. Family: Verbenaceae

Other names

Djati; jati (Indonesia); kyun (Myanmar); sagwan (India); teck; mai sak (Thailand); giati (Vietnam); teca (Brazil)

Description

  • Medium to tall hardwood, growing 45m on favourable sites.
  • Usually bole (trunk) is 15m.
  • Stem is irregularly shaped and grooved, and typically the leaves are very large.
  • Stem diameter averages 1m but can grow up to 2.4m according to locality and conditions.

Occurrence

  • Among the most well-known world timbers.
  • Occurs naturally in the monsoon forests of:
    • India
    • Myanmar
    • Thailand
    • Vietnam.
  • Plantations:
    • Indonesia
    • Papua New Guinea
    • Africa
    • Solomon Islands
    • Fiji
    • West Indies.

Appearance

Colour

  • Heartwood is generally golden brown but can be grey-brown to red-brown.
  • Longitudinal streaks are often present due to the ring-porous structure of teak.
  • Sapwood is pale yellow, therefore well demarcated.

Grain

  • Grain is straight or occasionally interlocked.
  • Texture is uneven varying from smooth to coarse due to its ring porosity.

Uses

  • Construction: flooring, decking, framing, boards, cladding, fascias and barge boards.
  • Decorative: lining, panelling, turnery, carving, furniture (both indoor and garden), parquetry.
  • Others: best known for its long established use in the boat building industry; extensively used for decking, deckhouses, rails, bulwarks, hatches, weather doors, and planking; also used for cooperage, pipes and chemical vats.

Properties

  • Density: 670kg/m3 at 12% moisture content; about 1.5m3 of seasoned sawn timber per tonne.
  • Strength groups: (S6) unseasoned, (SD6) seasoned.
  • Stress grades: F4, F5, F7, F8 (unseasoned); F7, F8, F11, F14 (seasoned) when visually stress-graded according to AS 2082—2000: Timber—Hardwood—Visually stress-graded hardwood for structural purposes.
  • Joint groups: JD3 seasoned.
  • Shrinkage to 12% MC: 2.2% (tangential), 1.2% (radial).
  • Unit shrinkage: not available.
  • Durability above-ground: Class 1 (life expectancy more than 40 years).
  • Durability in-ground. Class 2 (life expectancy 15–25 years).
  • Lyctine susceptibility: untreated sapwood susceptible to lyctid borer attack.
  • Termite resistance: resistant.
  • Preservation: sapwood will impregnate with preservatives.
  • Seasoning: slow drying; drying rates vary between pieces; little degrade; some collapse may occur if you use high temperatures.
  • Hardness: firm (rated 4 on a 6-class scale) to indent and work with hand tools.
  • Machining: varies, but generally works with moderate ease. Silica present in the timber causes severe blunting of cutting edges—reduce your planing angle to 20° and use saws with tungsten carbide tips.
  • Fixing: pre-bore when nailing; holds nails and screws well.
  • Gluing: as with most timbers of an oily nature, machine and prepare surface immediately before gluing.
  • Finishing: varnishes, polishes and waxes well; readily accepts paint and stains.

Identification features

General characteristics

  • Sapwood: pale yellow, readily distinguished from heartwood.
  • Heartwood: brown to golden brown; sometimes streaky.
  • Texture: non-uniform, moderately coarse, straight grain and greasy feel.

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, 2000, AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes, Standards Australia.