Construction Systems
Cross-Laminated Timber (CLT) Construction
Taking the structural strength of timber to the maximum
The CLT system—Cross-Laminated Timber—is a construction system formed by cross-laminated layers of solid timber, typically pine, capable of supporting significant structural loads and spanning large distances through a prefabricated system with rapid on-site installation.
In recent years, the rise of prefabrication in architecture and growing environmental awareness have positioned this construction system as one of the leading options in our country, particularly for projects with high ecological and efficiency standards.
What is CLT timber construction?
The term CLT comes from the acronym Cross-Laminated Timber. Its numerous properties have made it a revolutionary construction system that, beyond being a trend, represents a paradigm shift in timber construction.
Cross-Laminated Timber (CLT) is a prefabricated construction system consisting of sawn timber boards glued together in layers at 90-degree angles.
The boards are glued under high pressure to form solid panels of variable sizes and thicknesses depending on the span or loads they must support. Between 3 and 7 layers are glued together, ensuring effective structural performance.
The fact that the layers are superimposed perpendicular to one another allows structural rigidity to be achieved in both directions. [1]
What are the uses of Cross-Laminated Timber (CLT) in construction?
Prefabricated timber buildings have become an increasingly widespread solution. Their numerous advantages over other construction systems—such as shorter construction times and greater control over details and costs—have popularized their use in both small- and large-scale architectural projects.
Currently, everything from single-family homes to high-rise residential buildings can be constructed.
Carbon12 Project
Currently, the tallest project built with the CLT system is Carbon12, an 18-story building located in the United States. Its construction process has been documented and published on a website to share the experience of what its developers proclaim will be the carbon-free construction of the future.
A Cross-Laminated Timber (CLT) structure or block can be used in most elements that constitute a building—walls, floors, roofs, and stairs, among others.
Furthermore, it is a construction method suitable for individual single-family homes as well as high-rise buildings for residential, commercial, or industrial use.
Let us examine each of the possible uses in detail.
Vertical Elements
1. Exterior Walls
Load-bearing walls up to 3 levels in height, reaching approximately 14 continuous meters, with the possibility of stacking additional elements if this height is exceeded.
2. Interior Walls
Load-bearing interior partition walls that can be protected or left exposed.
3. Party Walls
Load-bearing interior walls that separate adjacent dwellings or premises, thanks to their high acoustic insulation capacity and the possibility of increasing their section.
Horizontal Elements
1. Intermediate Floors
Continuous floors with versatile dimensions capable of spanning large distances, avoiding the use of columns that interrupt interior space.
2. Roof Floors
Solution for flat and pitched roofs; the corresponding insulation and waterproofing membranes are placed on top of it.
What are the advantages of using Cross-Laminated Timber (CLT)?
The fact that the use of CLT—Cross-Laminated Timber—has become popular in recent years is undoubtedly due to its numerous benefits over other construction systems, which have made it a highly competitive alternative in terms of technical performance, environmental impact, and costs.
The main advantages of using CLT are:
1. Structural Excellence
2. Prefabrication
3. Thermal and Acoustic Insulation
4. Hygroscopicity
5. Environmental Impact
1. Structural Excellence
Glued timber ensures excellent structural performance. It has a higher strength-to-weight ratio than other construction materials, such as steel or concrete, resisting tension and compression correctly and avoiding shear stresses.
Its high static efficiency—load-bearing capacity for low weight—allows for the construction of large cantilevers and open-plan spaces free of primary structures of columns and beams.
Furthermore, its lightness reduces foundation requirements in construction, lowering final costs.
Compared to conventional timber construction with studs and beams—light framing—CLT generates less movement, has greater bending resistance, and generally exhibits greater strength and durability.
Cross-Laminated Timber (CLT) also presents better fire resistance due to its high density. [2]
2. Prefabrication
As it is an industrialized system that can be assembled in the workshop in a few days and in parallel with the excavation and foundation phases, it is possible to carry out projects with very short execution times, simplifying and accelerating the assembly process. The reduction in construction times avoids disturbances to neighbors and lowers construction costs.
Pieces of various sizes can be formed, favoring modular construction since the material imposes no limitations. It is a versatile method that allows custom design for each project. [3]
3. Thermal and Acoustic Insulation
Glued timber acts as a natural insulator both thermally and acoustically.
Acoustically, the porous composition of timber and its density allow it to absorb sound waves, preventing them from passing through the material.
Furthermore, CLT panels have low thermal conductivity, behaving similarly to an insulating material, but with the advantage of having much greater density, which gives them greater thermal inertia. This effectively ensures indoor environmental comfort in a building, both in summer and winter.
4. Hygroscopicity
Timber is a naturally hygroscopic material that has the ability to regulate ambient humidity.
When the relative humidity of an environment increases, timber walls or floors absorb water vapor, which is released again when the air is dry.
This inherent quality of the material represents a natural humidity control system that stabilizes the indoor environment, promoting the creation of healthy spaces.
Furthermore, it has been proven that absorbing and fixing vapor eliminates harmful substances from the air, which remain fixed in the timber and are not released again with subsequent evaporation.
5. Environmental Responsibility
The use of CLT is one of the most sustainable construction alternatives on the market, capable of reducing the impact of architecture on the environment. It is a renewable resource with low energy consumption in its manufacture, which considerably reduces greenhouse gas emissions compared to high-impact construction systems such as concrete or steel.
The raw material must legally come from forestry operations with Chain of Custody (COC) certification, a seal that verifies that the timber panels come from forests that have been properly managed or are from responsibly recycled sources.