What is Cross-Laminated Timber (CLT)?
Cross-Laminated Timber (CLT) is becoming an increasingly popular building material used in residential, commercial and public building projects. It offers many financial, environmental and performance benefits. In this post, we explain what CLT is, how it is produced and the many advantages it offers.
What is cross-laminated timber (CLT)?
Cross-laminated timber (CLT) is a type of engineered wood product that’s becoming increasingly popular in modern construction. CLT is made by stacking multiple layers of solid wood boards or planks at right angles to each other and then bonding them together with structural adhesives. The alternating layers create a crosswise configuration, which is what gives CLT its name.
How is CLT made?
The CLT construction process involves the following steps:
Wood selection
Typically, CLT is manufactured using softwood species such as spruce, pine or fir. This is because they are readily available, fast-growing and have good structural properties.
Drying
The wood boards are kiln-dried to achieve a specific moisture content. This ensures dimensional stability and prevents shrinkage or warping.
Layering
The dried wood boards are stacked on top of each other, with the grain direction alternating by 90 degrees between each layer.
Adhesive application
Structural adhesives, such as phenol formaldehyde resin or polyurethane, are applied between the wood layers.
Pressing and curing
The assembled layers are pressed together under high pressure and temperature. This allows the adhesive to cure and create a solid, strong panel.
The resulting CLT panel is a large, prefabricated building element with impressive structural characteristics. CLT can be produced in various dimensions ranging from smaller panels, suitable for walls or floors, to large panels that can span long distances. This makes it suitable for a wide range of construction applications.
What are the advantages of CLT?
There are many advantages to CLT, which make it a popular choice in a wide range of construction projects. These include:
Strength and stability
CLT panels have excellent load-bearing capacity and dimensional stability. This makes them suitable for both vertical and horizontal applications. They can be used for a variety of construction applications, including walls, floors, roofs and even tall buildings. They exhibit high strength-to-weight ratios, which allows them to provide structural stability and resilience.
Sustainability
CLT is made from renewable and sustainably sourced wood, which can be responsibly harvested. The production process requires less energy compared to other construction materials like concrete or steel. It is more eco-friendly than these carbon-intensive materials because the wood used in CLT retains carbon dioxide that was absorbed during tree growth, making it a carbon sink.
Rapid construction
CLT is prefabricated offsite which results in faster onsite construction. This can significantly reduce construction time, leading to cost savings and earlier building occupancy.
Lightweight
Despite its strength, CLT is relatively lightweight compared to traditional building materials. This makes it easier to transport and handle during construction.
Fire resistance
Due to its thick layers and the charring effect, CLT can offer good fire resistance, which allows it to maintain its structural integrity in the event of a fire.
Design flexibility
CLT can be used for a variety of architectural designs and can accommodate different shapes and configurations. Its strength and dimensional stability enable the construction of large, open spaces without the need for numerous internal supports.
Thermal performance
CLT provides good thermal insulation, which helps to maintain comfortable indoor temperatures and reduces energy consumption for heating and cooling.
Acoustic performance
CLT panels possess natural sound-dampening properties. This contributes to improved acoustic performance within buildings.
Seismic performance
CLT has shown promising seismic performance due to its dimensional stability and strength. It can withstand seismic forces and provide enhanced safety during earthquakes.
The combination of these advantages makes CLT an attractive choice for a wide range of construction projects, including residential buildings, commercial structures, educational facilities and public buildings. Its sustainability, versatility, and performance characteristics position CLT as a leading material in the move towards more eco-friendly and efficient construction practices.