Stevens

LaRCH

The photographs of the wood species are solely illustrative and may differ from reality.

General
  • the hardest and most durable European specie
  • reddish-brown heartwood and yellowish-white sapwood
  • innumerable interior applications: staircases, wooden floors, cladding, furniture, decoration
  • also for supporting structures, wall cladding, poles, sleepers, wooden tiles, bridges and flat-cut veneer.
  • exterior joinery, such as windows and doors

Origin

The larch belongs to the Pinaceae family and has ten different varieties. They only grow in the northern hemisphere of Europe, Asia (including Eastern Russia and Siberia) and North America.

lariks

Varieties

European larch
The European larch (Larix decidua Mill.) is found for example in the Alps, Poland, the Czech Sudeten Mountains and the Slovakian Tatra Mountains.
In addition to the European larch, the Japanese larch (Larix kaempferi (Lambert) Carr.) is also found in Europe. It was introduced in the 19th century and proved more resistant to larch cancer than the young indigenous larches. It therefore gradually gained the upper hand on the European larch in lower-lying forests. Japanese larch wood is slightly less heavy and durable than European larch wood, but more stable.
The hybrid larch variety Larix eurolepis Henry is a natural cross between the European and the Japanese larch. It has a high growth potential and is highly resistant to larch cancer.

Asian larch
Larix kaempferi (Lambert) Carr. or Larix leptolepis from Japan
Larix potaninii Batal. from the West of China
Larix sibirica Ledeb. from Eastern Siberia and the east of Manchuria up to Kamchatka
Larix mastersiana
Larix griffithiana (Lindl. and Gord.) Carr. from Nepal.

North American larch
Larix occidentalis Nutt. from the American states of Oregon, Washington, Idaho, Montana and British Columbia
Larix laricina (Du Roi) K. Koch. from the east and north of Canada and the northeast of the United States
Larix lyallii.

Appearance

The larch tree grows rapidly and loses it needles quickly. This helps to enrich the spruce pine forests. It also contributes to tree diversification: bushes and herbaceous plants grow in the light that penetrates its crown, benefiting the fauna and flora. The larch also provides excellent protection to other, more slowly growing, tree species planted at a lower level.

Colour and figures

Larch wood changes abruptly from early wood to late wood. That can easily be seen from the growth rings. The late wood is also darker and denser than the early wood.
The heartwood is reddish-brown and darkens in the light and with age. It is clearly distinguishable from the sapwood. This is yellowish-white and extremely narrow in larch from mountainous areas.
Larch wood generally has a straight grain and a fine, to moderately coarse texture. Larch from planes with a temperate climate have a coarse texture.

Density

The late wood has a fairly constant width, regardless of the radial growth speed. Nevertheless, the global density of the wood decreases as the growth is accelerated. Larch wood has the highest density of all pine species and is generally grouped as a semi-heavy, semi-hard wood. Rapidly-growing wood from the planes nonetheless has a lower density and is therefore less strong.

Durability

The heartwood is moderately durable (natural durability class III) and is sensitive to termite damage. The sapwood is not durable (natural durability class V).

Drying and Moisture Content

Larch wood dries easily. It has to dry slowly at a relatively high temperature (75 °C) to remove as much resin as possible and limit the risk of splitting and loose knots.  After drying, the lumber has a distinctive, lasting resin scent.

Wood-working

Larch wood is easy to work, both mechanically and manually. Resin sometimes sticks to the sawing tools, which can lead to abnormal heating.
Larch wood is highly resistant to compression. It splits very evenly. The lumber is moderately stable.
The larch trunk is often bent near the bottom. The heart may therefore sometimes be extremely eccentric, forming reaction wood, which causes interior tensions and abnormal distortion.

Sanding, planing and gluing.

There are no problems with sanding, but it sometimes makes the fibres of the early wood stand up. Pay attention to the fairly hard knots. They are sometimes loose. You can only glue freshly planed larch wood, preferably with basic glues.

Finishing and treating

Finishing correctly dried larch wood poses no problems. The resin-rich parts should, however, be degreased before finishing the wood with paint, varnish, wax or stain.
Larch wood for exterior joinery requires treatment in accordance with procedure C1, followed by C2, CTOP or a finishing paint.
Thanks to its colour, texture and durability, larch wood can also be used unfinished. The wood becomes grey in time and retains its natural effect.
Larch wood for interior supporting structures requires treatment in accordance with procedure A2.1, unprotected structures in accordance with procedure A3 and poles in accordance with procedure A4.1

Attaching

If you wish to attach wood, then pre-drill it, as larch wood splits easily.

Applications
  • Interior joinery
  • Exterior joinery
  • Poles, wooden tiles
  • Chalets/Cottages
  • Structural elements
  • Veneer
  • Glued laminated timber
Professional information

Larch

Larch

Douglas  Fir

Whitewood

Average density*

600 kg/m³

550 kg/m³

450 kg/m³

Radial shrinkage

60 to 30% r.a.h.**

0,6%

0,8%

0,8%

 

90 to 60% r.a.h.**

0,7%

1,2%

0,9%

Tangential shrinkage

60 to 30% r.ah.*

0,9%

1,3%

1,5%

 

90 to 60% r.ah.**

1,3%

1,9%

2%

Wood-working

60 to 30% r.ah.**

1,5%

2,1%

2,3%

 

90 to 60% r.ah..**

2%

3,1%

2,9%

Flexural strength

94 N/mm²

85 N/mm²

71 N/mm²

Modulus of the elasticity

10.600 à 14.500 N/mm²

11.000 à 13.200 N/mm²

10.000 à 12.000 N/mm²

Compressive strength (parallel with the fiber)

54 N/mm²

55 N/mm²

45 N/mm²

Tensile strength (parallel with the fiber)

101 N/mm²

94 N/mm²

85 N/mm²

Shear strength

9,9 N/mm²

8,6 N/mm²

6,3 N/mm²

* at a wood moisture content of 15 percent / ** relative atmospheric humidity

 

Commercial information

Thickness x width

19 mm x 75/100/125/150/175/200/225 mm

25 mm x 100/125/150/175/200/225 mm

32 mm x 100/125/150/175 mm

38 mm x 100/125/150/175/200 mm

50 mm x 100/125/175/200/225 mm

63 mm x 125/150/175/200/225 mm

75 mm x 150/200/225 mm

95 mm x 95 mm

98 mm x 98 mm

 

 

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