Understanding mass timber
There’s a growing revolution in the building industry, as mass timber continues to evolve from an emerging technology to the preferred norm for structural building components in British Columbia (B.C.). These innovative, sustainable building materials, created using B.C.’s renewable forest resources, are inspiring new perspectives for all building types, changing the way in which projects are designed, built, and experienced.
The family of engineered wood components known as mass timber can be used in place of steel or concrete to create a structure that provides durable, cost-effective performance with less embodied carbon. Mass timber is used to construct everything from tall timber towers and long-span sports arenas to office buildings, multi-family structures, educational facilities, and more, adding value in terms of warmth, wellness, and workability.
There are many reasons why architects, owners, developers, and other building professionals choose mass timber for their projects. These engineered products are manufactured using wood, one of B.C.’s renewable resources. They offer a structurally efficient yet low-carbon alternative to steel or concrete. Building codes continue to advance in favour of mass timber construction, giving designers more opportunities every day to innovate. And mass timber can be used to differentiate a development by creating a unique design aesthetic that allows the natural beauty of the wood to shine through.
wək̓ʷan̓əs tə syaqʷəm Elementary School Seismic Replacement | Photo credit: Bright Photography
What is mass timber?
Mass timber describes a family of engineered wood products known for their strength, durability, versatility and sustainability. Mass timber products are made by taking smaller wood elements such as dimension lumber, veneers, or strands and connecting them with adhesives, dowels, nails, or screws to create larger structural building components.
These load-bearing building materials can be used in a wide variety of structural applications: beams and columns; floor, roof and wall panels; tall wall framing studs or roof rafters; door and window headers; and more.
Cross-laminated timber (CLT)
CLT consists of layers of kiln-dried dimension lumber (usually three, five, seven or nine) oriented at right angles to one another and then glued to form structural panels. By gluing layers of wood at right angles, the panel delivers excellent structural rigidity in both directions. These panels can be used both horizontally and vertically for floors, roofs, and walls—even elevator shafts. Strength and dimensional stability make CLT a solid choice for many applications, especially tall wood structures.
Glue-laminated timber (Glulam)
Glulam can be used as beams, purlins, and columns. It is incredibly versatile; glulam can be arched, used to support long spans, paired with other building materials, or just left exposed to provide beautiful structure.
Nail-laminated timber (NLT)
Formed using dimension lumber stacked on edge, then fastened together with nails or screws. Panels are typically used for floors and roofs, although they can also be used for other applications. NLT is appreciated by many for its natural aesthetic.
Dowel-laminated timber (DLT)
Made without adhesives or metal fasteners, so it can be easily modified with a wide variety of surface profiles. DLT is a structurally efficient, cost effective mass timber panel option.
Laminated strand lumber (LSL)
Suitable for shorter headers and smaller beams, tall wall studs, and other areas where uniformity and consistency are important. It is usually used for structural framing that won’t be visible.
Parallel strand lumber (PSL)
Well-suited for applications where high bending or compression strength is required, such as long-span beams, heavily loaded columns, and large headers. It can be used in both interior and exterior applications.
Lower-carbon construction
Construction materials contribute significantly to the world’s overall CO2 emissions. Mass timber products are manufactured using wood, a renewable resource. They have a smaller carbon footprint than steel or concrete, making them the material of choice for design professionals who want to mitigate the negative environmental impacts of traditional construction. In addition, wood naturally sequesters carbon, which means that the stored carbon will remain in the material for as long as the product remains in service.
Glue-laminated timber fabrication | Photo credit: Nik West
Design versatility
Engineered for strength and durability, exceptionally strong yet lightweight, mass timber offers something for everyone. Wood’s light weight helps building designers reduce foundation requirements, which saves time, money, and carbon by using less concrete. Mass timber material specifications can be configured to meet specific requirements, such as long spans, heavy loads, or exterior exposure. Because of its natural beauty, most mass timber products can be left exposed in certain building types, eliminating the cost of adding additional interior finish materials. Mass timber can even be combined with other materials in hybrid configurations designed to meet special loading or lateral requirements.
Wii Gyemsiga Siwilaawksat Student Building, Coast Mountain College | Photo credit: Bright Photography
Speed of construction
Time is money in the construction industry, and mass timber use speeds construction. Materials can be prefabricated, which means that they arrive at the jobsite cut to exact length or with pre-cut openings. They can even be pre-fitted with connectors, so that components can be lifted directly from the truck and into place at the jobsite, saving time and reducing impact on the surrounding neighbourhood. Mass timber installation requires fewer workers onsite, which also helps mitigate safety risks. Prefabrication also reduces jobsite waste, and since B.C. is home to many suppliers of high quality mass timber products, logistics are simplified.
Alliance Française | Photo credit: Arkitek Creative
Biophilic and wellness
Wood has recognized advantages when it comes to creating an environment that fosters health and wellbeing. When building occupants are exposed to natural elements like wood, it creates a direct connection with nature that has been shown to help improve mood, health, productivity, and comfort. Many architects and developers are using mass timber to help entice workers back to the office, using wood’s natural warmth to create a unique, engaging occupant experience.
oN5 | Photo credit: KK Law
Community and societal benefits
Use of locally made products manufactured from renewable resources benefits everyone in B.C. Use of mass timber creates jobs—from timber harvesting and trucking to manufacturing, fabrication, and installation. Because these products are made by combining wood elements, manufacturers can use smaller diameter logs harvested during thinning operations, designed to protect forests from wildfire. Some mass timber components can even be made using fire- and insect-damaged timber, which helps support active forest management that will help B.C. continue to sustainably manage its forests.
Forest harvesting operation in B.C. coastal region | Photo credit: Nik West
Mass timber can be used in many applications and building types, so it’s important to understand the strengths and advantages of each product when designing a project. There is an ever-evolving number of options and systems when it comes to mass timber. Using various combinations and sizes, mass timber products can serve as beams, columns, floors, roofs and walls considering the directional strength of each wood product. In contrast to conventional concrete and steel systems that tend to follow standard templates, mass timber systems offer the potential for greater flexibility, albeit not without some challenges.
Hybrid mass timber systems
Mass timber can be combined with light-frame wood, concrete, steel, or almost any other type of material needed for the building’s structural needs. A hybrid approach capitalizes on the unique strengths that each material brings to the project, using the right material for the right application. Common examples include mass timber with steel braced frames or concrete shear walls, a steel framed building with CLT, DLT, or NLT panels, or even mass timber-concrete composite panels.
Trout Lake Community Centre | Photo: KK Law
Post-and-beam system
These systems, which echo the type of framing used in traditional heavy timber buildings, combine beams, posts, and decking, all connected using steel fasteners. Posts and beams are typically glulam, although some projects may use PSL. Decking can be CLT, NLT, DLT, or other types of timber frame decking.
Earth Sciences Building | Photo: KK Law
Mass timber floor and wall systems
In contrast to post-and-beam, designers can take advantage of mass timber panels’ two-way spanning capability. This can include mass timber panels constructed to form a honeycomb structure well-suited to handle both vertical and lateral loads. In these systems, mass timber panels—similar to reinforced concrete and steel—form both floor and wall, with the walls bearing the load of the structure. In some instances, mass timber may form the core of a building, in place of concrete.
KF Aerospace Centre for Excellence | Photo: Shawn Talbot
Tall wood
The sky’s (becoming) the limit when it comes to using mass timber, as building codes evolve to allow taller mass timber buildings —up to 18 storeys in B.C. Mass timber’s high strength and light weight are ideally suited to the task, and prefabrication enables safe, speedy installation. Mass timber products can be precisely manufactured, which allows the building to go together with the precision needed for tall buildings.
Construction of Brock Commons Tallwood House | Photo: KK Law
Designers can create high performing buildings using mass timber. Building codes and technology are constantly advancing which may help designers create and optimize the value added. Here are some of the most common design considerations.
Code compliance
Mass timber has been accepted by building codes for decades, but changes recently made to the British Columbia Building and Fire Codes (B.C. Codes 2024) enable development of mass timber buildings of up to 18 storeys for residential and office buildings. The changes pave the way for projects with more exposed mass timber or fewer layers of encapsulation, depending on a building’s height.
Further Reading
Mass Timber Navigator: Understanding energy and code considerations for mass timber buildings
Brock Commons Tallwood House: Code Compliance Case Study
Seismic performance
Because of wood’s high strength and low weight, mass timber structures are uniquely capable of withstanding lateral movement due to seismic or wind forces. Wood is naturally ductile, which means mass timber elements can flex and return to their original shape when forces are applied. In addition, mass timber elements weigh substantially less than comparable steel or concrete assemblies, giving wood an extra advantage when subjected to lateral forces. Read more about wood’s resilience and performance attributes.
Acoustics and Vibration
Occupant comfort is key to a successful building project, and mass timber can help building designers meet their acoustical and vibration requirements. Acoustical sound mats, lightweight concrete, or other materials are typically placed over the top of CLT, NLT, or DLT floor panels to increase the mass of the floor structure and limit sound transition and impact noise. In addition, there are many techniques available to control vibration of a mass timber floor panel. Learn more about designing for acoustics and vibration in mass timber buildings.
Insurance
Historically, insurance companies have been reluctant to insure mass timber buildings, primarily because they were unfamiliar with the material and because technology was advancing so rapidly. FII and others in the industry continue to work to educate insurers on the safety and performance of mass timber buildings.
Further Reading
A Guide for Insuring Mass Timber in Canada
Insuring your next mass timber project
MEP Integration
Because mass timber panels, beams and columns can be prefabricated to precise tolerances and delivered to the jobsite with pre-cut openings, designers can collaborate with builders to make upfront decisions that facilitate fast, efficient installation of mechanical, electrical, and plumbing systems within the structure.
Fire resistance
Mass timber possesses inherent fire resistance properties. When exposed to heat and flame, the material chars; this outer layer of char protects the member’s interior, which allows it to maintain its structural integrity. Mass timber elements are sized so that the building can be supported even if the wood members are charred. All mass timber building components are fire tested and rated to ensure compliance with building regulations for occupant safety. B.C. has also adopted provisions from the National Building Code that allows for encapsulated mass timber construction up to 12 storeys.
Mass timber decision tools
As mass timber offers a growing number of structural solutions, design professionals can leverage new industry tools and resources to assist with conceptual testing, analysis and trialling of different design options. From online calculators and software to the latest guides and research, explore this collection of mass timber tools to find the best design solution for your project.
New guidelines for designing tall mass timber buildings
Engineers and Geoscientists BC and the Architectural Institute of British Columbia (AIBC) have published new guidelines to clarify the expectations for professional practice for architects and engineers designing mass timber buildings up to 12 storeys.
Brock Commons Tallwood House | Photo credit: KK Law
B.C. leads the way with mass timber buildings
Looking for project ideas? Check out these innovative, inspiring mass timber projects. The list is searchable by market segment, material, and location. There are more than 370 buildings in B.C. using mass timber, from public structures to commercial and multi-family residential applications, explore buildings using mass timber in our project gallery.
Get free technical support for your next timber-built project
WIDC Construction | Photo credit: Paul Alberts (Ardor Media)
Find B.C. mass timber suppliers
B.C. is home to a growing number of mass timber suppliers located throughout the Province. The B.C. Wood Supplier Directory connects you with forest product suppliers—including mass timber and engineered wood products. These quality producers continue to innovate and explore the possibilities for new products, applications, services, and technology.
Photo credit: Wade Comer