Cross-Laminated Timber Reaches new Heights: Why use CLT in Construction?
The growth of the world’s population has led to an increase in housing and building construction around the globe. Considering that today the construction industry is responsible for 40% of the planet’s CO2 emissions, and according to the Chilean Chamber of Construction, by 2035, Chile will need housing for 2.6 million people, it is necessary to guide this sector toward an environmentally friendly alternative. The answer to this challenge can be found in nature itself, where there are various efficient and sustainable construction solutions. Such is the case with wood: a noble and renewable material capable of capturing CO2 and contributing to a better environmental future.
Today, thanks to technological advances, engineered wood or laminated wood, composed of layers of structural wood oriented perpendicularly to each other, has positioned itself as a trending construction material worldwide, and Chile should not be the exception.
Wood Architecture Projects Worldwide
Internationally, the versatility of laminated wood is already gaining prominence in a number of renowned projects. For example, in the case of the double-curved roof of the ‘Idaho Central Credit Union Arena’ in the United States, laminated wood is used as a structure to create a large public space using local resources.
In another similar case, following a parametric planning process and precise production of components, the construction of the 5 floors of ‘Swatch Headquarters’ employs a wooden framework in combination with laminated wood elements.
In combination with various materials, the ‘Cathedral of Christ the Light’ is built using a hybrid system composed of a primary framework of prefabricated laminated wood and reinforced concrete, covered by a glass enclosure.
The importance of wood as a construction material is also highlighted in tall buildings, as shown by the 53-meter height of the ‘Vancouver Brock Commons’ student residence. Its construction was carried out using a wooden structure where the prefabrication of modular components—previously designed in BIM—played a crucial role in managing costs, time, and waste in the construction process.
The growth of this global trend is clear: according to Fernando Marcone, Wood Construction Deputy Manager at Arauco, since 2008, 66 wooden buildings with over 7 floors have been completed, 18 are currently under construction, and as of February 2022, there were already 55 proposed projects ready to begin.
Wood Projects with a Chilean Stamp
The endless structural and design possibilities offered by laminated wood have also left their mark on pioneering architects’ projects in Chile, who, through Arauco’s Hilam brand, have chosen it as a construction solution for various buildings. Among them, the ‘Casa 165’ by PAR Arquitectos stands out. By bringing wood into saline environments, the team of architects managed to replace steel as the primary resource, preventing its degradation over time and harnessing its structural strength.
In their pursuit to explore new material combinations, Benjamin Oportot and Maurizio Angelini use wood as a structural material for the development of the ‘E2E Offices.’ Starting with a square measuring 12 x 12 meters and a grid of 1.2 x 1.5 meters, a structure is created based on a system of braced frames on all four facades and coffered beams, meaning in both directions. For the architects, the choice of radiata pine for the structural wood stands out due to its excellent workability, allowing for intricate cutouts and recesses with high precision.
Regarding high-rise buildings, as a pioneering project in Chile and the region, the “Tamango Project” by Tallwood ventures into the construction of the first 12-story building using a CLT structure. Setting itself apart from traditional construction in the area, Tamango establishes a new paradigm based on an integrated and sustainable design process. For this initiative, the team had to import CLT, but for future projects, Arauco will soon offer CLT domestically to promote the widespread use of this construction technique in the country.
CLT by Arauco in Construction: A New Solution for Chile
Manufactured using Radiata Pine, CLT is a structural product formed from three, five, or seven layers of sawn wood arranged perpendicularly to each other. Its structural rigidity in both directions allows the panel to have good resistance to both tension and compression.
In 2022, Arauco announced the modernization of its Hilam Laminated Wood plant located in the town of Cholguán, VIII Region of Chile. This revamped plant, which is now in its final stage, will enable the production of CLT panels with state-of-the-art technology. These panels can have widths of up to 3.5 meters, lengths of up to 13.5 meters, and thicknesses ranging from 60mm to 300mm.
Another significant innovation of the Hilam plant is its ability to machine elements according to a 3D model. “Now, we will not only produce basic inputs for the construction industry,” says Fernando Marcone, Deputy Manager of Arauco’s Wood Construction Business, “but we will also be able to deliver ready-to-install CLT panels with pre-cut openings for doors and windows, aligning with the concept of industrialized construction.”
Promoting a high level of coordination among the client, architect, engineer, technical-commercial team, and construction team, the new Hilam plant offers complete organization in the production process, giving architects the opportunity to confidently design buildings of various uses, dimensions, and heights using wood as the foundational construction material.
Driving Paradigm Shift from the Project’s Inception
The creation of a structural wood project begins with design consultancy, followed by 3D modeling in BIM of the building, where dimensions, wood type, structural grade, thickness, width, and geometry of each element are adjusted. Through the mechanization of wood pieces using CNC machines, a project can be manufactured with millimetric precision. Laminated beams – curved, straight, and of various shapes up to 40 meters in length – are joined using finger joints and presses. The formation of modular panels provides greater speed and automation in transportation and assembly. Wood as a construction material allows the project to continue capturing CO2 during its lifespan. Moreover, its assembly offers the possibility of being disassembled for recycling or used as energy in new processes.
The versatility of this solution enables its application in various structural elements, including load-bearing walls (both exterior and interior), shear walls, slabs, and ceilings. It can be used in residential homes, residential buildings, as well as educational, commercial, and industrial projects.
Why Use CLT in Construction?
In addition to being a renewable resource, CLT serves as an excellent bracing product with a high capacity to withstand both vertical and horizontal loads. Unlike concrete and masonry, it is a lightweight product that minimizes air infiltrations, enhancing the thermal efficiency of buildings. Its mechanization enables modular construction based on the assembly of large wood panels.
However, despite its advantages, in Chile, only 13% of building permits are submitted for wood projects. According to Fernando Marcone, it’s not enough to be a forestry powerhouse and have the technology that facilitates the use of wood in buildings; “a paradigm shift in the way we design and construct a project must be promoted.” “Chile has a long tradition of using reinforced concrete in construction, and that’s why the entire industry is set up to operate under the logic and business model inherent to that material – the so-called traditional construction. If we want to promote sustainable construction with wood, the country needs to change the current way projects are developed, starting from the conception and design stage,” he concludes.
In addition to manufacturing high-tech Hilam wood, Arauco is also working on other fronts alongside other relevant stakeholders such as Madera21 from Corma, the Center for Wood Innovation at Catholic University of Chile, the National Wood Center, and the National Institute of Standardization. Their objective is to advance in the regulatory development for the use of wood at all levels, thereby increasing the competitiveness of this material.