Understanding Mass Timber in Construction : A Revolution in Building Materials

In recent years, there has been a significant buzz around a groundbreaking construction material known as Mass Timber. Let’s delve into what exactly Mass Timber is, its role in tall wood building construction, and the numerous benefits it brings to the table.

Mass Timber : A Versatile Engineered Wood Marvel

At its core, Mass Timber is a form of engineered wood that achieves remarkable strength and stability by layering and bonding wood panels. This material is not confined to a singular purpose; it can be employed for structural panels, columns, beams, load-bearing structures, and even interior finishes. An outstanding example of Mass Timber in action is the Brock Commons Tallwood House in Vancouver, Canada, a towering 17-story structure showcasing the prowess of Mass Timber construction.

Exploring the Mass Timber Family

The Mass Timber family encompasses various products such as Cross-Laminated Timber (CLT), Glue-Laminated Timber, Structural Composite Lumber (SCL), Nail-Laminated Timber (NLT), and Dowel-Laminated Timber (DLT). These diverse options contribute to the adaptability of Mass Timber in construction applications.

Mass Timber’s Emergence in Tall Wood Building Construction

Responding to the surge in interest in tall wood buildings, the International Code Council (ICC) formulated proposals embedded in the International Building Code (IBC) 2021. This code introduces three distinct categories for tall wood building construction using Mass Timber or non-combustible materials.

• Type IV-A : Maximum 18 stories, with non-combustible protection on all Mass Timber elements.
• Type IV-B : Maximum 12 stories, limited area of exposed Mass Timber walls and ceilings allowed.
• Type IV-C : Maximum 9 stories, permitting all Mass Timber to be exposed (with exceptions) and designed for 2-hour fire resistance.

The IBC 2021 outlines the maximum height limits, Fire Resistance Ratings (FRR), and non-combustible protection requirements for Mass Timber building elements within these categories.

Defining Mass Timber in IBC 2021 Terms

According to the 2021 IBC, Mass Timber is defined as “Structural elements of Type IV construction primarily of solid, built-up, panelized, or engineered wood products that meet minimum cross-section dimensions of Type IV construction.” These categories, stemming from the existing Type IV-HT (heavy timber construction), necessitate additional Fire-Resistance Ratings (FRR) and heightened levels of noncombustible protection.

Advantages of Embracing Mass Timber in Construction

Now, let’s shift our focus to the compelling advantages that Mass Timber brings to the construction arena:

• Fire Resistance : Mass Timber exhibits fire-resistant properties, with its surface charring during fires, forming an insulating layer that protects the interior wood.
• Structural Strength : The combination of load-bearing wood panels in Mass Timber results in a highly strong and stable structure, offering versatility in structural integrity.
• Lightweight Construction : Mass Timber is notably lighter than concrete and steel, reducing foundation size, seismic forces, and embodied energy.
• Sustainability : Leveraging lumber as the primary raw material, Mass Timber promotes sustainable practices, reducing carbon dioxide emissions compared to traditional steel construction.
• Cost Efficiency : Despite not being the cheapest option, Mass Timber construction proves to be 25% faster and requires 90% less construction traffic than concrete, making it a cost-efficient choice.

In conclusion, Mass Timber construction is gaining momentum due to its impressive combination of strength, sustainability, and innovation. Reports indicate a surge in projects adopting Mass Timber, marking a positive trend toward a more sustainable and efficient future in construction practices.