The climate emergency has forced the architecture sector to reconsider its traditional formulas and adopt new models intended to down the rate of damage inflicted on our planet. Measures that include choosing more sustainable building materials over others whose use has a greater impact on the environment during production processes, thereby increasing CO2 emissions, one of the major causes for rising global temperatures and climate change.
In this context, and thanks to technological advances, wood has re-emerged as a natural and renewable material in a new building era defined by sustainability. Indeed, wooden buildings are making their presence felt in some of the world’s major cities. And the CLT system is making a decisive contribution to this expansion.
So, what exactly is CLT?
CLT (Cross Laminated Timber) is a system that uses solid wood panels made up of layers of lumber boards stacked crosswise and glued into place. The cross laminated panels feature a symmetrical transversal structure comprising at least three layers, guaranteeing their rigidity as a structural material. Its applications include walls, floors or roofing.
The CLT system first appeared during the 1990s in Austria and Germany, and since then its use has extended around the world. It is suitable for use in all types of mainly mid-rise buildings (homes, offices, schools and hospitals, etc.). However, it has also been used in conjunction with other mass systems such as GLT (Glued Laminated Timber) in order to build wooden skyscrapers</strong>.
What’s more, new urban developments promoted by companies such as Google, renowned around the world for their innovation capacity, have opted for CLT.
The benefits of CLT
More eco-friendly: CLT offers the building sector a renewable, recyclable and reusable material. The trees planted to produce CLT store up carbon during their lifetime, removing it from the atmosphere.
Compared with the ton of CO2 emitted into the atmosphere for every cubic metre of concrete produced, wood from certified forests is estimated to absorb a total of 887 kg of CO2 per m3 during its growth phase. The environmental footprint of a wooden structure is between 60% and 75% lower than an equivalent made of steel and/or cement.
Lightweight: As a structural material, CLT offers a good resistance/weight relation. It is lighter than reinforced concrete, but has at least the same degree of resistance. However, whilst a cubic metre of concrete weights approximately 2.7 tons, the equivalent in CLT weighs just 400 kg.
Fast building: It takes less time to construct a wooden building using the CLT system. The high degree of prefabrication cuts on-site work time and there is less likelihood of unforeseen events. It is also a cleaner, dry system that generates less waste.
More space: CLT allows for the creation of open spaces, making it easier to eliminate pillars and main beams, obtaining up to 10% more habitable space.
Heat insulation and sound proofing: CLT provides excellent thermal insulation, whilst its rigid, porous composition also absorbs sound and guarantees excellent acoustics in any space.
Aesthetics: In addition to thermal and acoustic comfort, CLT can be left as it is in interiors (saving on the need for coverings), taking full advantage of woods’ aesthetic qualities and warmth.
Passivhaus: The insulation and precision offered by the CLT system have a positive impact on a building’s hermetic level and thermal characteristics, a definite advantage for compliance with Passivhaus energy efficiency standards.
Performance in the event of fire: A number of treatments bolster CLT’s resistance to fire. North American researchers have conducted real trials that have revealed good performance levels in the event of fire.