Thermowood 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 see our claddings type page for our profiles

Heat treated timber (Thermowood)

Surface treatment is not essential.

30 year UK service life

Please visit http://www.thermowood.fi  for information about Thermowood

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.

Heat treatment of wood was scientifically studied by Stamm and Hansen in the

1930s in Germany and by White in the 1940s in the United States. In the1950s,

Germans Bavendam, Runkel, and Buro continued research into the subject.

Kollman and Schneider published their findings in the 1960s, and Rusche and

Burmester in the 1970’s. More recently, research work was carried out in

Finland, France, and the Netherlands in the 1990s. The most intensive and

comprehensive research work was conducted by VTT in Finland. Significant

practical research is also being done by YTI (the Institute of Environmental

Technology).

Thermowood is manufactured using a method developed by VTT. The wood

material 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 wood. As a result of the treatment,

environmentally friendly Thermowood is created. Its colour darkens, it is more

stable than normal wood 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.

Changes to wood structure

Heating wood permanently changes several of its chemical and physical

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

hemicelluloses. Desired 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 wood, the wood

becomes lighter, equilibrium moisture content decreases, pH decreases, and

thermal insulation properties are improved. However, thermowood’s rigidity and

strength properties are also changed.

Extacts taken from the finish thermowood association handbook

Please visit http://www.thermowood.fi  

Phone Sales : 07800662931

Accounts : 01494 435144

Fax: 08712369322

Click here to e mail: sales@benchmarkdesigns.co.uk