Heartwood for windows  

There is more to timber than meets the eye. Obviously, there are difference between the characteristics of the various types of timber, but two pieces of timber of the same type can also have very different characteristics.      

Timber can be characterised as follows:
  • Heartwood/sapwood
  • Density – tree rings and resin content
  • Growth area
  • Cutting-out
  • Storage, drying and transportation                          

Timber that has grown slowly is strongest and best suited as timber for windows. The heartwood is from the core of the trunk, and its primary function is to give the tree strength. The outer layer is sapwood, which transports water from the roots to the crown of the tree. The heart is “dead”, so it no longer transports any water. The cells become filled with “waste materials” to protect themselves against rot and mould. This particular characteristic makes heartwood especially suitable for the manufacture of windows.


Advantages of using heartwood
  • No need to buy impregnation fluid
  • No man-hours spent impregnating the wood  
  • Shorter lead time and optimised production flow
  • A more eco-friendly solution  
  • Optional guarantee for the finish
Guarantee for heartwood portion

 VTI gives you a guarantee for the proportion of heartwood we agree with you. Selecting each individual log begins with high-tech X-ray sorting at the Nordic sawmills. When raw materials arrive at VTI, we carry out quality control of the timber to ensure the right quality for the finished goods. Before comb-jointing and lamination, we scan the profiles to facilitate cutting out of visible defects and knots.    


 The finished timber profiles are also sprayed with a heartwood reagent to verify the correct proportion of heartwood.

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The photos above show a piece of pine found in a bog in south-western Norway.

The piece of timber was examined at the Radiological Dating Laboratory, Norway, and estimated as being approximately 4,500 years old.

As the photograph shows, the timber is entirely fresh, and also smelt of freshly planed timber when sawn up.


Contact person

Jacob Wernberg


Jacob Wernberg


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

Lars Henrik Olsen

Quality and Development Manager

Lars Henrik Olsen


+45 96 95 03 27+45 96 95 03 27