Man has used wood as a building material since prehistoric times. However, with the emergence of reinforced concrete, its relevance has progressively declined. This change has caused a sharp reduction in the use of wood in construction. In this sense, society began to associate wooden structures with fragility, temporary nature and limited durability.

Current environmental policies are primarily focused on urgently reducing carbon dioxide emissions. In this context, the use of wood as a construction material acquires a new perspective of viability. Wood, being a renewable natural resource, easy to recycle and with the capacity to retain carbon dioxide, emitting it only during combustion or decomposition, stands out as an environmentally sustainable option and in line with current environmental preservation requirements.

CLT panels in construction

Currently, new construction methods have emerged that use wood as a structural material, introducing an innovative product intended to revolutionize the Construction of High-Rise Buildings. This new wood derivative, called CLT (Cross Laminated Timber), has a remarkable load capacity combined with a reduced weight, allowing the creation of highly slender elements, even in large spans dimensions. Compared to other structural systems commonly used in construction, this method presents new possibilities for distributing loads.

CLT, as a relatively recent wood derivative (developed around 1990), highlights the advantages and minimizes the disadvantages of using wood, becoming an increasingly popular construction solution in the construction industry. Still lacking specific and uniform standards, as it is not included in Eurocode 5 (Eurocode used for the design of wooden structures), this material is being subject to continuous studies and research, aiming at its comprehensive regulation, something expected in a near future. Part of its positive reputation is associated with a growing global concern for environmental sustainability. Essentially, as it is a renewable material, CLT presents itself as a deeply sustainable solution.

CLT is a material derived from improved wood, combining favorable characteristics and mitigating disadvantages, thus becoming a material of great relevance in the construction industry. However, it is important to highlight that this material has inherent advantages and disadvantages.

Wood House – project with prefabricated wooden structure.

Advantages of CLT

With regard to the positive aspects of CLT panels in construction as a structural element, their resistance, durability, ability to provide thermal and acoustic comfort, hygroscopic regulation capacity, as well as their performance in fire situations and in the face of seismic action. The resistance that a CLT panel offers in conventional “reduced” buildings is equivalent, at least, to the structural compression resistance of reinforced concrete. This last one, being flexible, needs to undergo considerable deformation before collapsing.

In addition to presenting at least the same support capacity as reinforced concrete for this type of construction, CLT stands out for the reduction in density per m³, compared to concrete and steel, representing approximately 20% of the density of reinforced concrete. The durability of CLT panels varies according to the tree species and the biological degradation process, as they come from a natural and biological material, wood.

A Passive House is a type of building that ensures thermal comfort and air quality without depending on mechanical ventilation systems, based on the concept of low energy consumption, following five principles:

• Adequate levels of insulation of the building envelope;
• Passive House windows and doors that comply with the standard;
• Ventilation system with heat recovery;
• Air tightness of the building envelope;
• Avoid thermal bridges in the building envelope.

A building built in CLT can easily be qualified as a Passive House, as it meets the previously listed requirements that are directly associated, that is, all except those that do not depend on the structural material, CLT.

Disadvantages of the CLT

Despite the various advantages that CLT offers, there are some disadvantages to consider that may discourage its application in construction projects. Construction with CLT tends to be more expensive when compared to traditional methods. This is due to the need for highly specific procedures in the production of panels, which require specialized equipment. Furthermore, these materials are available on a small scale and geographically limited, which implies additional transportation costs to the works.

As it is a recent material, there is still little history, study and knowledge about CLT, both on the part of architects and designers and on the part of owners. Associated with these factors, there is also the issue of availability, since the small number of companies specializing in CLT limits the supply to the capacity of these companies. On the other hand, another major disadvantage of using CLT is its fragility when in direct contact with the soil, due to humidity. Therefore, the use of CLT on the ground floor is not recommended, unless specific clearance solutions such as “basements” are adopted, together with additional waterproofing and ventilation measures. CLT panels are produced with precise cuts, following specialty projects, requiring them to be developed with high precision and geometric rigor.

Final considerations

The UT (Urban Timber) system seeks to make CLT a more versatile and attractive material for the construction market. It aims to adequately respond to the quantitative and qualitative demands of the buildings that will shape the cities of the future. In addition to the advantages, this method offers better use of space and uses its flexibility to respond effectively to current needs.

In short, it is crucial to highlight that the search for new construction systems in CLT must continue, making the most of the multiple qualities of the panels, generating new approaches to thinking, designing and building with wood.

Are you interested in exploring the potential of CLT panels in construction? You can count on MJARC’s services. From architecture to engineering, we have professionals and partners who will help you achieve your goals. Contact us for more information!