Energy-efficient timber as a new glulam product  

Heat treatment – or, more correctly, thermal modification – is a drying process that changes the chemical composition of the timber. The process is variable and depends on which dimension is being treated.


Finished window made from heat-treated timber

 The process is basically divided into three phase
  • Heating
  • Treatment
  • Cooling  
 What actually happens, technically speaking
  • A change occurs in the chemical composition of the timber
  • The usual nutrients for mould and wood destroying fungi are purged
  • The pH value of the timber is reduced  
  • The equilibrium moisture content of the timber is halved
 This offers a great many advantages and new possibilities
  • The dimensional stability of the timber improves by up to 50%
  • The insulating capacity of the timber improves by more than 30%
  • The biological durability of the timber improves from Class 3–4 to 2–3, in accordance with the EN350-2 standard
  • The density of the timber is reduced by approximately 8%

Heat treatment does not significantly alter the screw resistance of the timber and surface treatment with paint using the same paint systems used for ordinary pine heartwood is possible. Thus, there is little or no limitation in terms of technical production changes if you switch to heat-treated glulam – and you do not need to invest in any new production equipment.  

You should bear in mind that heat-treated timber is slightly more brittle, so the strength of the timber is slightly reduced. However, this will not be an issue with correct use of the timber, and the Technological Institute of Denmark has tested the timber for tensile strength, load-bearing capacity, deformation and deflections. Of course, all tests comply with the requirements for the production of windows and doors, cf. DVV (Danish Window Verification).

Contact person

Jacob Wernberg


Jacob Wernberg

+45 96 95 03 14+45 96 95 03 14