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Thermowood Cladding

Thermowood Cladding Suppliers

Heat treated Redwood Cladding  

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Thermowood the environmentally friendly alternative to tropical hardwoods.

Thermowood was developed to offer similar durability and stability properties to Western Red Cedar at a lower cost. We mill Thermowood decking and Thermowood cladding.

Thermowood is more knotty and harder than cedar. We mill with care ensuring the heart side of the timber is on the correct side into secret fix decking and cladding.

We import sawn Thermowood D Redwood which we mill to order.  We have selected Redwood because it is superior to whitewood which is often used.

Please also visit our profiles page for and our timber cladding page for more general information.

Thermowood garden room

Heat treated Redwood pine.

No Chemicals are used to make the timber resistant to rot.

Surface treatment is not essential.

30 year UK service life

Thermowood introduction

It has been known for centuries that burning the surface of wood in open fire will make it more durable in exterior use.

Even the Vikings used this method in outdoor structures such as fences.

Thermowood is manufactured using a method developed by VTT in finland. The timber is heated to a temperature of at least 180 degrees Celsius while it is protected with steam. Besides providing protection, the steam also affects the chemical changes taking place in the timber. As a result of the treatment, environmentally friendly Thermowood is created. Its colour darkens, it is more stable than normal timber in conditions of changing humidity, and its thermal insulation properties are improved. If carried out at a sufficiently high temperature, treatment also makes the wood resistant to decay. On the other hand, this has a decrease in the bending strength.

thermowood cladding

Changes to the timber structure.

Heating wood permanently changes several of its chemical and physical properties.

The change in properties is mainly caused by thermic degrading of hemicelluloses.

Changes start to appear already at about 150 ºC, and the changes continue as the temperature is increased in stages.

As a result, swelling and shrinkage due to moisture is decreased, biological durability is improved, colour darkens, several extractives flow from the timber, it becomes lighter, equilibrium moisture content decreases, pH decreases, and thermal insulation properties are improved.

However, Thermowood’s rigidity and strength properties are also changed.

Thermowood decking

Thermowood Decking

If you are uneasy using tropical timbers, Thermowood decking is an ideal alternative.

No chemicals are used to make the redwood pine durable. Treat only if you would like to retain the rich colour of Thermwood.

We mill the sides of our Thermowood decking to accept the Profix2 hidden fixing system.

Please visit our Thermowood decking page for further information.

Thermowood timber cladding

Detail Drawings

Factory Staining


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