Mass timber has emerged as a compelling alternative to traditional, carbon-intensive construction materials in recent years. This article will discuss the rise of mass timber and its benefits for the future of the construction industry.
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What is Mass Timber?
Mass timber structures are, as the name suggests, made out of wood. A key sustainable natural resource, if managed well, wood has been used to construct buildings since prehistory. However, mass timber structures differ from traditional wooden construction.
The key difference lies in the material itself. Mass timber is made from compressed layers of wood either glued, nailed, or dowelled together. The highly compressed wooden material is then formed into planks, panels, beams, and other types of structural elements for use in new buildings.
Mass timber can be used to complement light wooden elements, providing new and innovative design possibilities for architects and engineers. Indeed, many structural engineers and building designers are increasingly considering the use of mass timber in new commercial and domestic buildings.
Types of Mass Timber
Mass timber comes in various forms for commercial use. These include:
- Glulam (Glued laminated timber.) Often used as structural components, formed from layers of timber with the same directional orientation. Usually made from oak, spruce, larch, or fir.
- CLT (Cross-laminated timber.) Also known as “super plywood.” Different pieces of wood are glued together at right angles to create a panel. This type of mass timber has two-directional structural rigidity and is used to produce structural walls and floors. Usually constructed using spruce, pine, or larch.
- DLT (Dowel laminated timber.) Similar to CLT, DLT is used for roof decks and floors. Cheaper and faster to produce than CLT as there is no need for gluing. Constructed using friction-fit hardwood dowels to join together layers of softwood.
Does Mass Timber Perform as Well as Conventional Construction Materials?
In order for a material to be considered for use in construction, it must meet stringent performance and safety standards. Traditionally, buildings have been constructed out of materials such as concrete, brick, and steel due to their favorable material characteristics.
Mass timber has comparable properties to conventional materials. It is incredibly strong but more lightweight than steel and has superior flameproofing properties, making buildings made from mass timber safe to use. Traditional wooden structures require treatments to reduce fire risks, whereas mass timber does not.
Another favorable characteristic of mass timber is its low carbon footprint. This is highly attractive to a construction sector that is increasingly more concerned with sustainability and meeting net-zero targets. Responsibly sourced wood used in mass timber reduced the embodied carbon of new builds considerably.
Construction times can be reduced through the use of mass timber as well. Quicker, cleaner assembly is facilitated by this somewhat revolutionary material. Additionally, as it is lighter than other more widely used materials, mass timber saves resources such as fuel for transporting building components to the site.
However, whilst the use of mass timber has grown significantly over the past few decades, there are still some potential limitations. Wood is a biodegradable material; therefore, protecting structures is vital. Furthermore, there is still limited data on risks and durability in these structures. Anisotropy in different wood types is also an issue.
Testing the Earthquake Safety of Mass Timber Structures
Mass timber has gained interest as a low-carbon structural alternative for high-rise buildings of the future. Whilst the favorable strength, low carbon footprint, and fireproofing abilities of this material are well documented, one critical concern is whether these buildings can withstand seismic activity in earthquake-prone regions.
To test the potential for mass timber as a material in earthquake-prone regions, Lever Architecture, a US-based studio, alongside several industry experts, tested the ability of a 112-foot, ten-story mass timber structure to withstand seismic activity. This test was the largest to date on such a structure.
Conducted as part of the NHERI TallWood project, the test used the world’s largest shake table to simulate earthquakes with a magnitude of 6.7 – 7.7. Data gathered during testing confirmed the sufficient resilience of mass timber high-rise buildings during seismic activity.
Earthquakes can cause immense upheaval in affected areas, with the damage to buildings being so extensive that usually, they would have to be torn down and rebuilt. This displaces populations as the time taken to reconstruct neighborhoods can be extensive and resource-intensive.
Replacing conventional concrete, brick, and steel buildings in these areas with mass timber constructions speeds up recovery from seismic events as they can be repaired quicker and immediately reoccupied by residents. Furthermore, buildings can self-center.
In Summary
The construction industry has to find new and innovative solutions to current sustainability issues. Mass timber, where layers of wood are tightly layered using various techniques, offers advantages in terms of a low carbon footprint, less embodied carbon, comparable mechanical properties, and fireproofing.
Recognizing the benefits of constructing tall structures and domestic dwellings out of this environmentally friendly material, many architects and engineers have extensively tested mass timber and incorporated this structural material in the design of new building projects since the technology’s inception in the 1980s.
However, more testing on critical factors such as durability and biodegradability is required in this emerging area of construction if mass timber buildings are to become commonplace. The sustainability benefits of phasing out carbon-intensive materials in favor of innovative green materials such as mass timber are clear, however.
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Further Reading and More Information
Ayanleye, S et al. (2022) Durability and protection of mass timber structures: A review Journal of Building Engineering 46: 103731 [online] sciencedirect.com. Available at:
https://doi.org/10.1016/j.jobe.2021.103731
Ravenscroft, T (2023) The Dezeen guide to mass timber in architecture [online] Dezeen.com. Available at:
https://www.dezeen.com/2023/03/01/dezeen-guide-mass-timber-revolution/
Dreith, B (2023) Largest earthquake test for mass-timber tower successful in California [online] Dezeen.com. Available at:
https://www.dezeen.com/2023/07/25/largest-earthquake-test-for-mass-timber-tower/
Naturally:Wood (2023) Mass timber and taller wood construction [online] Naturallywood.com. Available at:
https://www.naturallywood.com/topics/mass-timber/
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