Clear Pine Thermowood®’s density is 350 - 480 kg/m3 when its moisture content is 6%. Natural variation will occur between individual boards. It is also both light and easy to work with but can be brittle and care should be taken during storage and installation to avoid any unnecessary exertion of stresses. International Timber Thermowood® Red Pine has a slightly higher density than International Timber Thermowood® Clear Pine.

Dimensional Stability

Clear Pine and Red Pine Thermowood® has on average 40% greater stability than untreated softwood, suffering less shrinkage, swelling, and distortion due to atmospheric changes.

Durability and Decay resistance

Clear Pine and Red Pine Thermowood® has improved durability when used in above ground applications as the treatment process destroys the rot-causing hemicelluloses which nourish fungi and bacteria. It also has high resistance to most decay fungi. Whilst it does not resist the biological growth of algae on its surface, this aesthetically unpleasant but non-damaging occurrence can be avoided by treatment.

Thermal Conductivity

When compared with normal kiln-dried softwoods its thermal conductivity is reduced by 20-25%, making it an ideal timber for external cladding application with a ?10 in the region of 0.107 W/(mK).


Whilst nail holding strength values for wire and improved nails are consistent with the values for European Redwood, screw holding strength is reduced by approximately 20% due to the altered state of the cell wall during the thermal modification process.

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