Siberian Larch has long been used for cladding in North Europe. SILA A/B® is Russwood's registered trademark for heartwood of Siberian Larch. Russwood introduced Sila A/B® into the naturally-durable timber cladding market, previously dominated by Western Red Cedar.

It is a very strong and robust, relatively knot-free and visually consistent species suitable for all types of cladding application. Russwood can supply a selected quality SILA A/B® grade of Siberian larch, (The GOST sorting grades which are used in Russia and sold by most UK merchants do not meet our standards for natural durability or appearance.)

Data sheet

• Wood type – Softwood.
• Environmental - Available from well-managed sources some with FSC certification. Russwood's FSC no. SGS CoC 1272.
• Source – Siberia, Russia.
• Tree - Attains a height of 25m to 40m and a diameter of 60cm or slightly more, with a long, clean, cylindrical bole for two-thirds of its length. It is a natural mountain tree, requiring long, extremely cold winters for its best development.
• Deciduous - and depends upon a long winter rest for the ripening of its wood.
  Timber - Heartwood: Pale honey to reddish-brown colour. It has clearly marked annual rings, a straight grain, and a fine, uniform texture. It is heavy, weighing 725 kg/m3 when dried to 18%.
• Drying - Dries rapidly.
• Strength - A hard, tough timber, it is about 70% harder than Scots pine and slightly stronger in bending and toughness; in other strength categories it is about the same as for Scots pine.
• Working Qualities - Medium. (Refers to ease of working and is classed as good, medium or difficult.)
• Durability - Naturally durable
• Treatability - Extremely difficult for vacuum pressure processes. (BS EN 350-2)
• Moisture Movement - Small. (Refers to the dimensional changes that occur when dried timber is subjected to changes in atmospheric conditions.)
• Density (mean, Kg/m³) - 725 (Averages at 18% moisture content are quoted)
• Texture - Fine
• Use(s) - Cladding, flooring, decking.
• Colour(s) - Light reddish-brown. Relates to the heartwood of the species. Most timbers vary in colour and will change with use, the application of finishes and exposure to light.

Sila A/B® Sawn Boards

Specification of Sila A/B® of Siberian Larch: Practically centre free, one face sap free, tight live knot structure of max 25mm in diameter; resin pockets maximum of one per 2.5m; kiln dried to 16-18% moisture content which is the optimum moisture content for external timber cladding. Lengths 6.0m - 2.4m with max 5% 1.8 - 2.1m. Please note Sila A/B® does not include low quality GOST Grade 3/4 material, common in the UK market.

Sawn boards - sizes available:

• 25 x 100/150/200
• 38 x 150
• 50 x 100/150/200