Lightweight yet strong, with superior acoustic, fire, seismic, and thermal performance, cross-laminated timber is currently being used in place of concrete, masonry and steel in the construction of commercial, industrial and residential buildings.
Excellent structural properties and load transferring capabilities combined with a low self-weight allow CLT to be used as load bearing structural elements in mass timber structures with highest freedom of architectural implementation.
egardless of building material, fires start in the contents and furnishings brought into homes and offices, and occur in concrete, steel, masonry, and wood buildings alike. What’s most important is building to code to ensure safe buildings for occupants and first responders.
Building codes require all building systems to perform to the same level of safety, regardless of the material used.
CLT construction has a proven safety and performance record for fire protection, and the addition of sprinkler systems, fire-resistance-rated wall and floor assemblies can be used to safely increase the allowable size of solid wood structures.
CLT Fire safety research here
Wood has natural advantages. For instance, through its low λ value and its ability to adjust to the diffusion processes CLT has the ability to regulate room humidity and climate.
CLT has relatively good thermal insulating characteristics. Heat conductivity or so-called lambda value, expressed in W/mK, comparable with, for example lightweight concrete and there is substantially lower than for concrete and steel.
CLT has a comparatively high specific heat capacity (thermal inertia). Usually it is around 1300 J/kg°C and compared to concrete which has around 880J/kg°C.
As a natural renewable product performance can vary slightly, although commercial CLT generally achieve:
• thermal conductivity: λ = 0.13 W/mK
• density: 480–500 kg/m3
Combining CLT with proper insulation materials allows to reach highest thermal performance of Passive building standards.
CLT is both aesthetically pleasing and provides advanced acoustic properties. Often used in theatres and cinemas, timber and plywood contain sound absorbing and echoing reducing properties. The prefabrication of CLT panels makes onsite construction almost soundless, providing adequate protection from noise disturbance as an important factor for ensuring a sense of well-being in buildings.
Acoustic properties of buildings constructed of mass timber meet the highest standards of modern living environment.
Parametric studies were carried out on the direct impact airborne sound insulation of CLT floor assemblies (with/ without various floor topping and gypsum board ceiling variants), on the direct airborne sound insulation of CLT walls (with/without gypsum board linings), as well as on the structure-borne sound transmission on a series of CLT building junctions. The results were then used as input data for predictions of the apparent impact and airborne sound insulation in real CLT buildings using the ISO 15712 (EN12354) framework that was originally developed for concrete and masonry buildings.
Wood has been used as a building material for millennia, but the health benefits of wood are only recently being studied and understood. While many people agree wood is visually pleasing, researchers are discovering that wood can contribute to the health and well-being of building occupants. With 90% of time spent indoors due to nowadays restrictions, studies have shown that indoor environment plays a significant role of person`s mental condition. As stated by Multiple researches, use of natural materials such as wood seems to reduce stress levels and improve productivity and creativity.
A common goal of environmental responsibility pushes construction industry to more sustainable solutions. As a renewable resource material with Carbon negative traits CLT has serious environmental benefits and allows to reach highest sustainability standards of modern Green building requirements. Maximizing wood use in both residential and commercial construction could remove an estimated 21 million tons of C02 from the atmosphere annually – equal to taking 4.4 million cars off the road.
Wood also performs better than concrete and steel when it comes to air and water pollution. Wood’s advantages are recognized by green building rating systems— including certified wood, recycled/reused materials, local sourcing of materials, waste minimization, indoor air quality and life cycle impacts.
Due to high degree of prefabrication, the mounting of CLT panels take much less time, has better logistics because of minimal panel weight and modular dimensions. There is a need of much less human resources on site and the installation process is much quieter and cleaner than with traditional building methods.
High winds, hurricanes and earthquakes are a harsh reality for some of global regions. These unpredictable climates require special consideration of wind- and seismic-resistive engineering. Solid wood buildings can be designed to stand up to high winds and earthquakes given these characteristics:
Inherent Flexibility: Wood’s ability to withstand high loads for short periods of time and retain its elasticity and ultimate strength can be an asset in seismic and high-wind zones.
Lightweight: Solid wood buildings typically weigh less than those made of concrete and steel, reducing inertial seismic forces.
Redundant Load Paths: The fasteners and connection systems used in CLT construction offer multiple, redundant load paths for extreme forces, reducing the chance of structure collapsing.
Strength and Stiffness: The thickness of mass timber panels and the number and size of fasteners connecting the assemblies determine each component’s stiffness. Heavy bracing for shear walls can resist lateral distortion common in earthquakes.
More on CLT seismic resistance research here.