Last week I was in Slovenia for a tour of Riko’s timber factory in Ribnica, about an hour’s drive south of the capital Ljubljiana. I was invited there to look at their facilities as I am intending to make the Woodland Nursery out of timber, or — more specifically — out of cross-laminated timber panels (CLT).
Five layered CLT panel
Cross-laminated timber is large-format, innovative, engineered timber that is manufactured off-site. It was first developed in the sawmills of Austria and Germany in the early 1990s there are now CLT factories right across Europe, but not yet in the UK.
Although wood has been used in buildings for centuries, the development and production of large format CLT panels was the first time a wood product had been produced that matched the structural qualities of concrete, whilst being sustainable. It has one of the lowest energy consumptions of any building material across its lifecycle.
CLT panels are used for walls, floors and roofs of a building’s superstructure. It is produced from small softwood sections that would otherwise be of no great value, made up in layers at right angles and glued together under pressure using a polyurethane adhesive (with no formaldehyde or toxic emissions) – or laminated. These panels are light, stable and very strong.
Forests around Ribnica
Slovenia is one of the most densely forested countries in Europe, with forest and woodland covering 58 per cent of its surface area. Beech, spruce, fir and oak are the most common species. I was impressed by the seemingly endless mountains of unspoilt forest. Where are the scars associated with tree felling that we see so often in Scotland, I wondered? Slovenia has a principle of what the Ministry of Agriculture, Forestry and Food calls “close- to-nature forest management”, but it is no doubt helped both by the large number of small forest owners with small and fragmented tenure and that 50 per cent of forests are situated inside the EU Natura 2000 ecological network. The amount of felling lags behind the allowable cut determined in the forest management plans.
The barn at Škrabec Homestead were I stayed, used as a cultural venue, has a state-of-the-art CLT panel structure hidden behind a traditional exterior.
As far back as 1492, the Austro-Hungarian emperor granted an imperial patent to the people of Ribnica for their wooden products after which they sold them all over the world. Sadly now, Slovenia exports much of its unprocessed timber to be processed in Austria and then buys back CLT panels.
Riko Hiše, a subsidiary of Riko, was founded by Ribnica born, Janez Škrabec in the 1990s, and specialises in tailor-made prefabricated buildings. It manufactures a patented system incorporating structural panels, insulation (wood fibre), doors, windows, blinds, services, internal and external finishes. Riko’s team assembles the building on site, the panels being hoisted into position by crane and bolted together.
The advantages of prefabricated CLT panels include strength, speed and efficiency, as well as a light environmental footprint. They also produces less waste, improved thermal performance and design versatility.
Each CLT panel manufactured is cut and processed using state of the art CNC (Computer Numerical Control) technology. The precise tolerances achieved result in high levels of airtightness. This leads to benefits to health and well being, contributing to improved internal air quality. Studies in Norway indicate children who are taught in solid wood classrooms have heart beats that are 6 beats per minute slower than those taught in non-wooden classrooms.
It also has a surprisingly excellent performance in fire.
After the tour of the factory we went for a walk on some of the many paths through the forests around Ribnica. I was relieved not to encounter either a brown bear or a wolf, although at least I now know what to do if I do – play dead!
Traditional Slovenian timber barn