Questions and answers
Here you can find answers to frequently asked questions about CLT. Questions concerning the origin, production, structural and physical properties of CTL, and the product itself, are briefly discussed here.
Who is Stora Enso?
Stora Enso is a leading provider of renewable solutions in packaging, biomaterials, wooden constructions and paper on global markets. Our aim is to replace fossil based materials by innovating and developing new products and services based on wood and other renewable materials. We employ some 26 000 employees in more than 35 countries, and our sales in 2015 were EUR 10.0 billion. Stora Enso shares are listed on the Helsinki and Stockholm stock exchanges.
Wood Products Division provides versatile wood-based solutions for building and housing. Our product range covers all areas of urban construction including massive wood elements and housing modules, wood components and pellets. We also offer a variety of sawn timber goods. Our customers are mainly construction and joinery companies, merchandisers and retailers. Wood Products operates globally and has more than 20 production units in Europe.
What is CLT?
CLT stands for Cross Laminated Timber and is a solid wood construction product consisting of at least three bonded single-layer panels arranged at right angles to each other. From five layers, CLT can also include middle layers (transverse layers) without narrow side bonding. It currently measures up to 2.95 × 16 m. CLT solid wood panels are made up of several layers and are available in different panel thicknesses depending on structural requirements. CLT is made of spruce or pinewood derived from sustainable forests.
Where is CLT produced?
CLT is produced in Austria in our two plants at Ybbs on the Danube and Bad Sankt Leonhard.
Where does the wood come from which is used to make CLT?
We always endeavour to use domestic roundwood. However, due to the domestic roundwood situation, we often have to fall back on roundwood imports (e.g. from Slovenia or the Czech Republic). However, at the same time, a PEFC certificate is also required in the same way as for domestic wood.
Does CLT have PEFC certification?
Yes, CLT comes from sustainable forests and has PEFC certification.
What does PEFC stand for?
PEFC means “Program for the Endorsement of Forest Certification Schemes” and is the label for wood and paper products derived from environmentally, economically and socially sustainable forestry operations along the entire processing chain. For customers, the PEFC label gives confirmation that the purchase of a labelled product guarantees and supports environmentally sound forestry management. It guarantees that the product has been subject to monitoring in accordance with rigorous criteria from the forest to the end product. Evidence of compliance is provided by Stora Enso and is regularly checked by independent bodies.
What can be built with CLT?
CLT has universal applications ranging from carports, added floors and extensions, through to detached and terraced houses and even including nine-storey timber residential buildings. The product is also exceptionally well-suited to the construction of industrial buildings, supermarkets, nurseries and schools. Special buildings such as watchtowers and wind turbines have already been built and are proving successful in practice.
What is the lifetime of a house built with CLT?
With the right building physics construction methods, there is no limit to lifetime. Taking old wooden construction farmhouses as an example, it is clear that a lifetime of several hundred years is not an uncommon occurrence.
Which adhesive is used for CLT?
The surface and finger joints are bonded with a polyurethane adhesive (PUR). The narrow side is bonded with an EPI adhesive. The formaldehyde-free adhesives that we use do not pose a health hazard and the quantities are reduced as far as possible in compliance with the necessary requirements resulting in a very low proportion of glue of 1%.
Where can I purchase CLT?
CLT is used by many construction companies. Please contact your architect or local carpentry company for more information.