Mass timber is prefabricated engineered wood products that include the lamination and compression of layers to create solid panels of wood. Similar to steel or concrete, mass timber can be used as the primary load-bearing structure for buildings typically higher than six stories, such as a mixed-use building, residential and multi-family facilities or an office complex. What makes these mass timber products even more impressive is the fact that they can be massive slabs of wood up to 10 feet wide and 60 feet long.
Types of mass timber
Material types vary in the market, but cross-laminated timber (CLT) has made the most headway in the United States as of late. With three to seven layers of lumber stacked in alternating directions to create structural panels, CLT brings the strength, stability and rigidity to serve as structural floors, walls and roofs for large projects. In addition to its function as a building material, CLT can also be left exposed as part of interior design to bring a high-end aesthetic.
While CLT has largely been the most popular choice in the United States, there are additional types of mass timber being used. These types include:
- Nail-Laminated Timber (NLT): created from regularly measured lumber (2×4, 2×6, etc.) that’s fastened together with nails or screws
- Glued-Laminated Timber (glulam): consists of regularly measured lumber that’s been bonded together with a moisture-resistant adhesive
- Dowel-Laminated Timber (DLT): is made from softwood boards held together with dowels
- Structural Composite Lumber (SCL): created by layering wood veneers, strands, and flakes that are glued together with moisture-resistant adhesive
Mass timber construction project types
Designs featuring mass timber structures are ideal for buildings taller than six stories, with the new 2021 International Building Code allowing for mass timber developments up to 18 stories. Mass timber has been most often used in the mixed-use, multi-family, hospitality and corporate office markets due their repetitive bay size. Additionally, the exposed wood feel has office developers adopting mass timber to appeal to the next generations of the workforce.
Mass timber benefits
Mass timber is a sustainable building material becoming increasingly popular in the North American market due to its unique characteristics in comparison to steel and concrete.
Mass timber sustainability
Manufacturing mass timber produces lower carbon emissions than its counterparts of steel and concrete, making it a smart choice for clients looking to build with a green mindset. In fact, replacing steel with mass timber could reduce carbon dioxide emissions by 15 to 20 percent! Additionally, wood has natural thermal qualities, which means that with the correct thickness and measures, mass timber can significantly reduce heating and cooling costs.
Better fire safety
Its fire-resistant capabilities also mean a safer building – mass timber chars and creates a protective insulation that burns at a slower rate than steel and concrete. During a fire endurance test, a 5-ply CLT panel was tested against temperatures of over 1,800 degrees (F). The panel lasted over 3 hours, compared to the 2 hour requirement building code requires.
Shorter construction time
Another impactful reason to consider mass timber is the reduced time savings during construction. CLT structures have a reduced weight compared to steel or concrete, leading to a smaller foundation size. This in turn means less time and associated cost savings. In addition, speed of construction is quicker and more efficient with prefabrication, planning sequencing before delivery, fast assembly and easy changes in the field. Minimal labor is needed for installing a mass timber frame, yielding both schedule and cost savings.
According to WoodWorks, a wood products council, 1,169 multi-family, commercial or institutional mass timber buildings have been constructed or were in design in all 50 states since 2013.
With the many benefits and savings from utilizing mass timber, the possibility of seeing it on one of your projects is ever increasing.
