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Russwood’s Scottish Larch (Scotlarch®) is locally sourced timber which provides a durable, natural and cost-effective cladding solution.

As the construction sector becomes increasingly focused on combining energy efficiency and sustainability with the need to cut costs, Scotlarch® is the timber of choice for many project types.


Russwood only supply cladding using selected heartwood of Scotlarch®, with boards encompassing a warm mix of colours; from pale orange / brown through to reddish brown shades. In ideal conditions, this species weathers to a muted shade of silver / grey which is desirable in many cladding projects. 

There are frequent knots in Scotlarch® boards, which demonstrate the natural origins of the product and give it a characterful look.

Grades and specification

At Russwood we sort and re-grade every Scottish Larch board that we produce, in order to ensure that our in-house grading criteria are met.

Heartwood of Scottish Larch: Russwood Scotlarch®

  • Graded to BS1186-3 Part 4 Class 3; boards contain tight live knots with a maximum diameter of 50mm
  • Sapwood free on all exposed faces
  • Some resin pockets may be present
  • Air-dried to moisture content of approximately 16-18% (+/- 2%)
  • Lengths up to 4.8m
  • FSC-certified product sourced from sustainable forests in Scotland

NBS Specification

For advice on completing the NBS H21 for Scotlarch® please get in touch with our project team.


Scotlarch® is a naturally durable timber and, for external cladding purposes, is classed as “moderately durable” (class 3 according to BS EN 350-2). This is due to the tannins in the wood which create a resistance to decay.

With correct detailing (i.e. no sapwood on exposed faces) and appropriate fixings, Scotlarch® cladding should have a lifespan potential of at least 50-100 years. 

The way a façade is fixed and detailed can have a major effect on its lifespan. Our range of fixings and systems are designed by Austrian Timber Engineers to make cladding look better and last longer. 


Russwood’s Scotlarch® is carefully air-dried to approximately 16 – 18% (+/- 2%), the optimal moisture content for external larch cladding. The benefit of air drying this product, as opposed to kiln drying Scotlarch®, is that the timber is not subjected to the stresses of kiln drying, and therefore achieves optimum stability.

Once the Scotlarch® is air-dried, this enables machining of the product to achieve a superior finish. It is then ensured 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 and minimum of sapwood (all exposed faces will be sapwood free) Scotlarch® is a medium density timber, classified by BS EN 350-2 as approximately 556 Kg/m3 at a moisture content of approximately 18%. As such, it boasts excellent impact strength 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, supermarkets, visitor centres). 

Coating suitability

Scotlarch® is suitable for factory coating in SiOO:X, a breakthrough silicon technology, to provide a genuine silver lustre. In effect, SiOO:X 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:X click here


How timber is fixed is fundamental to it’s long term performance in terms of both appearance and durability. We offer a range of fixings and systems to make cladding look better and last longer. These systems can be written into the NBS H21 specification. 

Surface Finishes

We can produce Scotlarch® in three different surface finishes to suit your specific project requirements and vision;

  • Wire Brushing - To create this effect, wire brushes are used to pull out the softer spring wood, exposing the harder summer wood, thus accentuating the grain and creating a beautifully textured surface.
  • Skimming - To avoid an unsightly surface finish, we skim the face of each board to provide a clean, unblemished fine-sawn finish. 
  • Planed - Boards are run through our planing mill to create a smooth, dressed finish.


Most of our Scotlarch® originates within 100 miles of our Highland sawmill. In addition to the sustainability benefits this affords, Russwood’s Scotlarch® is FSC®-certified, meaning that it is sourced from well-managed forests.


Scotlarch® is available in varying lengths up to 4.2m, sawn widths from 47mm to 150mm, and sawn thicknesses of 22, 30, 35 and 50mm. Please note that cladding is supplied as a linear meterage based on random stock lengths at time of picking order. Other sizes may be available on request. 


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.


Please see our cladding comparison table for price range.


  • Locally sourced product
  • Innate durability
  • Natural look
  • Weathers to a muted grey tone
  • Sustainable
It is important to us to source sustainable and affordable timber from within the UK. At Bents Green School, Russwood provided us with friendly, detailed, and extremely helpful technical guidance, and in Scotlarch® a timber cladding which is attractive, flexible in design terms, and met our budget requirements.

Matthew Bradshaw, BDP