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SiberianLarch cladding

Russwood’s Siberian Larch (SILA) is the cladding of choice for many architects, contractors and self-builders, due to the fact that it is extremely versatile - being suitable for most external timber cladding applications - has excellent durability properties and displays attractive figuring. 


Russwood’s SILA boards come in a warm mix of colours, from light reddish brown through to golden browns. When weathered the colour changes to a muted grey tone, which is desirable in many cladding projects. 

With clearly marked annual growth rings, straight grain and relatively few knots the overall look displays attractive figuring with a contemporary look.

Grades and specification

In order to ensure that our stringent in-house grading criteria are met, we offer three grades; A/B, A+ and B/C, with the specifications being as stated below.

Russwood SILA A/B®

Russwood offers SILA A/B®, the highest grade of Siberian Larch cladding commercially available in the UK, which provides a clean and relatively knot-free look combined with excellent durability. The specification for SILA A/B® is as follows:

  • Graded to BS1186-3 Part 4 Class 1; each board is practically centre free, one face will be sap free and resin pockets are restricted to a maximum of one per 2.5m length
  • Tight live knots with a maximum 25mm diameter and a maximum of two knots per metre length
  • Kiln-dried to moisture content of 16-18% (+/- 2%)
  • Lengths of 1.8 – 6.0m with 95% of your boards being over 2.4m
  • We select from the best available grades in the UK and Holland to guarantee that your order will not contain any commonly available, lower quality - Sawfalling and GOST grades

Russwood SILA A+

Russwood also hand-selects boards from the A/B grade to meet stringent internal criteria for the supply of SILA A+. This is a clear grade timber, providing a clean, consistent, virtually knot-free look. The specification for SILA A+ is as follows;

  • Graded to BS1186-3 Part 4 Class 1; each board is centre free, one face will be sap free and resin pockets are restricted to a maximum of one per 3.0m length
  • Tight live knots with a maximum of 12mm diameter and a maximum of two knots per metre length
  • Kiln-dried to moisture content of 16-18% (+/- 2%)
  • Lengths of 1.8 – 6.0m with 95% of your boards being over 2.4m

Russwood SILA B/C®

Additionally, Russwood offers SILA B/C®, a more rustic grade of Siberian Larch than our A/B and A+ grades. It gives a more knotty, less uniform look, without compromising its excellent durability properties. The specification for SILA B/C is as follows;

  • Graded to BS1186-3 Part 4 Class 2; tight live knots have a maximum 35mm diameter and the majority of boards will have at least one sap-free face
  • Kiln-dried to moisture content of 16-18% (+/- 2%)
  • Fixed lengths of 3 & 4 metres
  • Some boards may feature canter/circular saw marks. We therefore recommend re-sawing when using as a board-on-board finish, to create a consistent bandsaw appearance

NBS Specification

For advice on completing the NBS H21 for Siberian Larch cladding please get in touch with our technical team.


For external cladding purposes, Siberian Larch is a naturally durable timber (Class 3 according to BS EN 350-2) due to a combination of factors;

  • Resin and extracts in the wood create a high resistance to decay and rot, making Siberian Larch one of the toughest and most durable softwoods
  • High density means that it is more difficult for decaying organisms to penetrate the wood

With a lifespan of 50 -100 years when subject to general outdoor exposure, this is similar to Russwood’s Architect Select Western Red Cedar. Better durability properties can only be being achieved with Russwood’s modified timber products; Accoya® wood and Natural Cladding ® Thermally Modified Hardwood. 

The way a façade is fixed and detailed can have a major effect on it’s lifespan. Our Russfix system is designed by Austrian Timber Engineers to make cladding look better and last longer. 


Extreme continental climates in Siberia (short, hot summers and long, cold winters) produce a high proportion of late wood, which enables a smoother machine finish and enhances dimensional stability.

Additionally, Russwood’s SILA is kiln-dried to 16 – 18% (+/- 2%), the optimal moisture content for external cladding. The benefit of kiln drying Siberian Larch, as opposed to air drying it, is that the timber dries uniformly and therefore achieves optimum stability.

Once the kiln-dried Siberian Larch is received at Russwood, this enables the product to be consistently machined to a superior level of finish. It is then ensured, through the use of stringent quality control processes, that the optimal moisture level is retained until delivery to site. The cladding can then be installed immediately upon delivery.


Due to its high percentage of heartwood (75-90%) and a minimum of sapwood (we guarantee that at least one face will be sap free) SILA is an extremely a dense timber, classified by BS EN 350-2 as approximately 628 Kg/m3 at a moisture content of 18%. As such, it is not easily damaged and therefore is ideal for highly exposed elevations, or applications where there is the likelihood of physical damage such as knocks or scrapes (e.g. schools, shopping centres, public walkways).

Coating suitability

SILA can be vacuum coated in Sioo, a breakthrough silicone technology, to provide a genuine silver lustre. In effect, Sioo creates a weathered appearance at an accelerated rate. Following application, all areas, regardless of protection and exposure, take on a consistent tone which provides a solution to differential weathering. For further information about Sioo click here.

SILA can also be vaccum coated in your choice of colour from Russwood’s Teknos paint range. Due to the infrequent knots and tight grain, optimal paint adhesion can be achieved, particularly when used on sawn surfaces.

SILA can also be fire-retardant treated, using either the NON COM® process, or using HR Prof as an on-site applicant. 


The way a cladding board is fixed and detailed can have a major effect on it’s lifespan. We have teamed up with Austrian fixings specialists, Sihga, to provide a system that makes cladding look better and last longer. These systems can be written into the NBS H21 specification. For more information, click here.


We can advise you on the most suitable species and profile for your project. Visit our profiles section to view some of our most popular profiles, or speak to us to discuss further options.


Russwood’s SILA is FSC®-certified, meaning that it is sourced from well-managed forests.


SILA is available in standard lengths of 1.8m up to 6m, widths of 75, 100, 150, 200 or 225mm and thicknesses of 22, 25, 38 and 50mm. Please note that these are standard sizes, but other sizes may be available on request.

We also have the ability to finger-joint and edge-glue SILA. This process allows the customisation of lengths, which could be particularly desirable in large-scale projects such as schools, retail units and other public buildings. Seamlessly joining shorter boards together can create a clearer, more dimensionally stable grade at longer lengths, which is often desired by architects and specifiers.


SILA is one of our mid-range products, with prices starting at £26 per m2 for sawn boards.


  • Clean and contemporary look
  • Suitable for most types of cladding application
  • Excellent density and durability
  • Stringent in-house grading of every board
  • Sustainable

For a printable summary of the above information, click here to download our Siberian Larch Cladding Factsheet