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Thermally Treated Pine Cladding


Thermopine® is a timber with enhanced stability and durability, produced by thermally modifying Scandinavian grown Scots Pine using only heat, steam and pressure. The principal benefit of Thermopine® is less substrate movement, meaning a paint coating can last up to three times longer than when applied to non-modified timbers, substantially reducing the maintenance requirement and in turn, the lifetime cost of the product. The advanced, highly controlled modification process results in a reduction of the wood’s tendency to shrink and swell whilst reducing its vulnerability to wood destroying organisms.


Russwood’s Thermopine® is suitable for use on a wide-range of projects, often utilised to create both modern and natural looking facades. In its uncoated state, Russwood’s Thermopine® has a uniform chocolate-brown colour tone which will quickly weather to grey, however due to the superior coating performance over species such as Larch, boards are most commonly supplied pre-treated using our factory coating system with black being the most popular colour choice.

The appearance after factory coating is largely determined by which surface finish is opted for. When coated in a translucent coating the knots and figuring become attractive features. In contrast, an opaque RAL coating will largely disguise the knots and figuring to create a more plain vernacular. When left uncoated, Thermopine’s golden brown colour will rapidly fade when exposed to UV light.

Sawn from slow grown, small diameter logs, Thermopine® boards display attractive, tight grain figuring with an abundance of live (structurally sound) round and splay knots, some of which may display cracks and chipped-off edges after machining, an occasional dead knot cannot be ruled out.


  • Enhanced paint performance due to outstanding dimensional stability.
  • Resinous substances removed during the heat treatment – resin exudation on the board face is eliminated.
  • Durability equal to that of Oak as per BS EN 350-2
  • Excellent price/performance ratio
  • No chemicals are used in the heat treatment process – no poisonous or hazardous waste at the end of life
  • Prominent figuring as a result of frequent knots
  • PEFC certified, meaning it is sourced from well-managed European forests
Modified Scots Pine
Northern Scandinavia
Density* Kg/m3 at 18% moisture content unless otherwise stated
450 (at 10%) - Low
Very Good
Durability Class* 1 is 'Very Durable' > 5 = 'Not Durable'
Suitability for Factory Coating
Very Good
Environmental Certifications
Modified Timber
Price From** per m² excluding VAT

Grades and Specification

  • Heartwood of Scandinavian grown Scots pine
  • Thermally modified to create dimensionally stable, Durability Class 2 (as per BS EN 350-2) material free from resin. Only heat, steam and pressure used in modification process; free from chemicals
  • Moisture content of approximately 6-8% (+/- 2%)
  • Centre-cut to include live knots. Unlimited number and size of knots, pith allowed
  • In maximum 15% of goods, chipped-off parts of knots permitted at no more than two chipped out knots per m
  • Lengths up to 5.7m
  • PEFC certified product, sourced from sustainable forests

NBS Specification

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


A major advantage of thermal treatment is its effect on the durability of the timber. Following the treatment process, Pine becomes a Durability Class 2 timber as per BS EN 350-2 – this is the same durability class as Oak. During the thermal process every cell of the timber is modified, the treatment penetrates throughout the entire board, ensuring consistently durable material.

The method with which the cladding is fixed and detailed can have a major effect on its lifespan. Our fixing systems will make cladding look and perform better for longer. We can advise upon the best option depending on the profile and cladding layout selected.


The heat treatment reduces the density by approximately 10% to 450kg/m3, making it relatively light in weight and easy to work.


For use as timber cladding, the main advantage of the thermal treatment is the resulting dimensional stability. Thermopine® is significantly more resistant to moisture absorption than unmodified timber, therefore shrinkage and swelling are decreased substantially. The reduction in dimensional movement can be up to 40-50%, which is of particular benefit to coatings. When Thermopine® is coated the resulting reduced movement levels mean the coating will last significantly longer, as it is not being forced to move with the normally experienced expansion and contraction of the timber.


Thermopine® is available in varying lengths up to 5.7m.

Surface Finishes

We can produce Thermopine® in three different surface finishes to suit your specific project requirements and vision. Each finish will look and perform slightly differently when used in combination with our Teknos® factory coating systems. Independent timber science research combined with our own intensive studies have shown that optimal coating performance can be achieved on a Microtex® finish.

  • 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.
  • Planed – Boards are run through our planing mill to create a smooth, dressed finish.


Due to it’s outstanding dimensional stability, Thermopine® is eminently suitable for factory coating in your choice of colour from Russwood’s paint range. However, it should be noted that when coating thermally modified timber using translucent paint or stain systems, some lightening of the colour tone is to be expected over time, particularly when lighter shades are selected. This is to do with the natural weathering of the timber rather than coating degradation. For further information on our factory coating system, click here.

Resin bleed is a common issue when coating unmodified resinous timber species, particularly in dark colours which are proven to absorb more heat. The thermal treatment process used in producing Thermopine® eliminates the issue by “burning off” resin so that it cannot exude in due course.

Thermopine® can be factory coated in SiOO:X, a breakthrough silicone 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.

Uncoated Thermopine® can also be fire-retardant treated by using an impregnation process.


How timber is fixed is fundamental to its long term performance in relation to both appearance and durability. We offer a range of fixings and systems designed by Austrian Timber Engineers to make cladding look better and last longer. There are a number of options when considering cladding fixings. Sihga’s FassadenClip® offers secret fixing giving a modern clean finish where no fixings are visible. Also available from Russwood is Sihga’s F-BohrFix® ZB screw for effective secret fixing of our RW119 secret fix profile. For face fixing applications, L-GoFix® screws combined with KompeFix® offer a superior look and performance to standard face fixing arrangements.

These systems can be written into the NBS H21 specification. For more information on our recommended fixings, click here.

Virtual Samples

Click on the 3D icon to view virtual cladding samples. Tilt and zoom in on the sample to view the texture, grain and colour of the boards and use the highlight feature to see how light and shade affect the aesthetic.

Profile Options

Thermopine® can be produced in the following profiles.

Sizes are subject to change in response to changes in moisture levels. Cladding will be kiln-dried to approx. 6-8% prior to machining, but may vary between production and installation on site. Cladding will be dispatched at given sizes, but a margin of error should be used when producing cladding layout drawings for expansion and contraction in the timber.


Standard widths: 92mm / 117mm
Standard thickness: 20mm

View profile


Standard widths: 92mm / 117mm
Standard thickness: 20mm

View profile


Standard widths: 92mm / 117mm
Standard thickness: 21mm

View profile

Surface Finish Options

We can produce Thermopine® in two different surface finishes to suit your specific project requirements and vision.


Planed boards are run through our planing mill to create a smooth, dressed finish.
Learn more

Wire Brushing

Wire brushing accentuates the grain and creates a beautifully textured surface.
Learn more

Coated Options

Thermopine® can be factory coated in your choice of colour from Russwood’s paint range, or with SiOO:X for a weather appearance at an accelerated rate. Thermopine® can also Fire Retardant treated but not in combination with another coating.


A consistently weathered appearance at an accelerated rate, available in orginal and pigmented versions.
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Factory Coated

A high quality pre-painted coloured finish with optimal long term product performance.
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Recommended Fixings

How timber is fixed is fundamental to its long-term performance in terms of both appearance and durability. These are the recommended fixings for use with Thermopine®.

L-GoFix® A2 Screws

Face Fix

Cladding screw for effective fixing and neat detailing.

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Face Fix

Compensation strip designed to prevent direct contact between timber elements.

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Russwood Battening System


Environmentally friendly, engineer-assessed, method of fixing timber cladding.

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Secret Fix

An innovative secret-fix solution for open rainscreen cladding.

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F-BohrFix® ZB Screws

Secret Fix

For optimal fastening of tongue and groove cladding.

Learn more