The Danish company Lacuna makes use of this old method and manufactures the majority of their doors with heat treated wood. Being concealed in large 198 degree hot ovens for 24 hours, the structure of the wood changes permanently and gains a number of advantages, which ordinary soft or hard woods do not have.

 

Natural durability, dimensional stability and low maintenance requirements

Not only does the heat treatment increase the natural durability (and becomes equal to teak -Class 1) it also makes the timber very stable, and accordingly it is unable to absorb moisture and expand in humid weather. This is obviously an essential attribute for folding doors, where many panels in succession need to keep their dimensional stability in order to function properly all year around. It furthermore means that the paintwork does not crack and maintenance therefore is at a minimum.

 

Insulation properties

Another advantageous effect of the heat treatment is the air-filled structure that the timber adopts. It basically gains the characteristics of fibreglass and consists of many small air pockets neatly packed together. It is these that give the wood the excellent insulation properties and thereby the low u-value.

 

Lacuna bi-fold doors: The materials have been tested at the German testing centre IFT- Rosenheim and subsequently the doors have been certified by the approved testing centre at Danish Technological Institute.
They have total u-values typically down to 0.9 W/m², air permeability has been tested to EN 12207 – Class 4 at +/-600 Pa, water tightness to EN 12208 Class E1200 and security to EN1627-30 / PAS24.