The CLT results from the juxtaposition of wooden boards to form plates that overlap and produce a panel. Massivity is guaranteed by bonding, and the boards of each of the layers of the panel are orthogonal to the adjacent ones.
The panels can reach large dimensions and are produced to measure specifically for each project. Thanks to the use of high-precision numerical control (CNC) machines, the panels are supplied with all the cuts and openings required for the project, ready for assembly.
The mass of the panels, associated with the physical and mechanical properties of the raw material, wood, guarantees very interesting performance levels at the structural, acoustic, or thermal levels. The CLT is suitable for pre-fabrication, allows for a clean and dry construction, and ensures remarkable levels of fire safety, as well as under the action of an earthquake.
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The mass of the panels, associated with the physical and mechanical properties of the raw material, wood, guarantees very interesting performance levels at the structural, acoustic, or thermal levels.
The growing popularity that CLT has gained is precisely based on its performance and versatility which has made it possible and competitive to consider wood as the main building material so far reserved only for reinforced concrete or steel (KLH).
There are 3 levels of visual quality for the exterior faces of the panels: Not visible, visible industrial, or visible domestic, each chosen according to the nature of the use of the construction. Visual quality levels do not influence the structural performance of CLT. Visual quality levels do not influence the structural performance of CLT.
KLH can produce panels with a maximum length of 16.5m, a width of up to 3.5m, and thicknesses ranging from 60mm to 360mm.
KLH CLT panels are manufactured using adhesives classified as Type 1 according to EN 15425, making them suitable for the production of timber elements with structural functions.
During production, KLH automatically applies the adhesive to the entire surface of the layers and then subjects them to a pressure of 0.6 MPa (N/mm2). This technology enables high-quality lamination, compared to vacuum manufacturing processes where the induced pressure is around 6 times lower, and results in superior structural performance.
TISEM started its activity in 2009, specializing in the design of wood structures with CLT panels, and is supported by one of the oldest manufacturers worldwide, KLH, with more than 30,000 projects carried out worldwide.
The CLT panels allow a contemporary and innovative design of the construction, are a credible alternative to traditional constructive solutions, offer high comfort and well-being, and are economically competitive and durable.
Construction with CLT panels favors compliance with carbon neutrality in construction through the long-term sequestration of CO2 that wood naturally stores. The KLH CLT Environmental Product Declaration highlights a negative balance on the global warming potential (GWP) that can be capitalised to compensate for the greenhouse gas (GHG) production that other materials applied in the building have, in particular, steel, aluminium, or concrete, the extraction, and processing of which require much higher amounts of energy.
For example, a house with a construction area of 100m2 can guarantee the sequestration of around 50 tons of CO2 equivalent.
The use of biomaterials to replace so-called traditional materials raises, at first glance, an essential question – Is cutting down trees to produce CLT compromising environmental sustainability? KLH sources its raw materials from sustainably managed forests (PEFC and FSC certifications), where replanting is carried out and it is ensured that the biomass existing in these forests is maintained or increased. In fact, because the value chain involved benefits from the consumption of these materials, naturally, the increase in demand results in the promotion of afforestation.
The planting of forests with the aim of producing wood for the construction industry, despite being ordered and based on monocultures, allows the sequestration of CO2 from the first day of planting, protects the soil against erosion and, despite everything, favors biodiversity.
In their process of growth and biomass gain, trees remove CO2 from the atmosphere and conserve it for as long as the wood lasts. For every cubic meter of wood used as an alternative to another construction material, we remove between 0.7 and 1.1 tons of CO2 from the atmosphere. This procedure also generates a multitude of activities linked to the exploration and transformation of its by-products, for example, in terms of heating homes or the production of organic matter to supply agriculture, which increases the resilience of rural economies. The greater the impetus for wood consumption, the greater the interest of populations in investing in their forests: looking after, enjoying and promoting their expansion.
Wood improves the health of the dwellings and promotes the quality of the indoor air. Its hygroscopic characteristics enable the absorption, retention, and release of water, regulating naturally the moisture content in the air. Prevents condensation and the appearance of fungi.
Visual contact with wood induces a feeling of relaxation and comfort. The wood in the construction is perceived as the extension of nature to the interior of the buildings, awakening in people the innate feeling of biophilia – sympathy for life. At the touch, it transmits heat.
Studies carried out in wooden buildings show that they play a relevant role in the prevention of cardiovascular diseases and the nervous system. The monitoring of its users recorded a significant reduction in the heart rate and an increase in the activity of the parasympathetic nervous system, that is, there is a better response of the brain to calm situations with a consequent protective effect for the cardiovascular system.
The CLT panels from KLH are produced with polyurethane-based adhesives, formaldehyde-free and volatile organic compounds (VOC) free.
Wood is a combustible material, but the evolution of combustion is predictable. On the other hand, when we talk about massive wood components, including CLT panels, the combustion advance only affects the mechanical properties of the wood section that has already burned, remaining in the non-burned wood portion. Together, these facts allow, at the design stage, to establish appropriate measures to delay or prevent the collapse of buildings, according to the requirements of construction and the safeguarding of people and goods. Steel, in turn, when exposed to high temperatures, yields and quickly loses its supporting capacity. As for reinforced concrete, it benefits from the protection that the reinforcement coating gives to the steel, but, reaching the limit of this protection, the risk of a fragile rupture of the elements with the collapse of the structure without warning.
A well-designed CLT building, under the action of an earthquake, achieves a unique performance in comparison with other structural solutions. Taking advantage of three factors – high plane stiffness, low weight, and ductility of the connections – the building has the potential to dissipate seismic energy without collapse and with low residual deformation. It thus allows to meet the damage limitation requirement imposed by Eurocode 8, even under a recurrence time action equivalent to the Ultimate Limit States.
For example, a typical façade built with a masonry solution reaches about 35cm thick, while its equivalent in terms of thermal performance with a CLT construction system reduces to about 20cm.
In the construction of passive houses (Passivhaus), where it is required to comply with a set of rules to achieve energy consumption needs close to zero with maximum indoor air quality and comfort, the CLT is an essential gain because it allows to eliminate flat thermal bridges and also greatly reduces linear thermal bridges while allowing to create an air-tight environment.
> Passive House
In a CLT construction, provided that false ceilings and/or false walls are avoided or limited, it is possible to achieve a thermal inertia of medium class.
The CLT panels from KLH are air-tight (conferred on ETA), and special attention should be paid to the joints between panels and the holes that break the watertight barrier (bonding line). In these areas, seals must be performed to ensure the continuity of the air barrier.
Some factors contribute to this fact:
