Lacuna Passivhaus suitable bi-fold doors
Heat treated timber…and why it is such a good idea…
Heat treatment is not a new invention – whenever a Viking ship has been found at the bottom of Roskilde Fjord in Denmark, it has nearly always only been the keel that has been intact. To bend the bow and stern keel, the Vikings heat-treated the wood in hot embers, using water cooling to ensure that it did not catch fire. Once the wood was warm and smooth, the keel was bent into the desired shape. In this way, the sugars (Lactose and Glucose etc.), which the decomposition bacteria would otherwise live off, were burnt away and the wood achieved the unintended effect of a lifespan of many centuries.
The Danish company Lacuna makes use of this old method and manufactures the majority of their doors with heat treated wood. Being placed in large 198° C 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.
Lacuna bi-fold doors - Thermal Performance
Whole window U-value (Uw) - as low as 0.85W/m²K
Frame U-value (Uf) - average 1.02W/m²K (centre leaves) - 0.92W/m²K (outer frame)
Spacer psi-value - as low as 0.029W/mK
Glazing U-value (Ug) - 0.775W/m²K or 0.725W/m²K
g-value - 0.5 (with the 0.775 glazing) or 0.38 (with the 0.725 glazing)
Lacuna bi-fold doors - Security
With internally beaded glazing (fixed with butylene sealant), toughened glazing as standard (laminated can be supplied), double rebate in frame, locks by Ruko/Assa on main door with 3-point locking system, 6-lever locks used as standard (and available in different configurations), 5.5mm marine-grade stainless-steel (316) hinges with security pins, hinges kept together by a bolt (which cannot be dismounted at the top) and all secondary door-blades being locked individually into both the top frame and the threshold – the Lacuna bifold doors are burglar-proof to the highest degree.
Individual .dwg and .pdf files can be downloaded from Lacuna (opens in a new window): http://lakuna.dk/index.php/technical-drawings.html
Please see our terms and conditions for more information.
5 Years on material and manufacturing defects. Please read our Lacuna Terms and Conditions and download Lacuna's Guarantee, Operation and Maintenance guide - Feb 2015
PLEASE WATCH THIS INSTALLATION VIDEO SEVERAL TIMES TO FAMILIARISE YOURSELF WITH ALL THE NECESSARY STEPS PRIOR TO FITTING.
IN PARTICULAR ONLY LIFT THE DOORS WITH GOOD QUALITY GLASS VACUUM LIFTERS OR YOU MAY DAMAGE THE SURFACE FINISH