Throughout the pandemic, health and safety have emerged as top-priority concerns across many sectors. In the construction industry, we have remained flexible – however, there is a possibility we will need to re-evaluate how we manufacture, engineer, and build future structures to address these concerns, not only in the coming months, but in the years ahead.
While mass timber may still be a relatively “new” building material in North America – having first been used in 2012 as an alternative construction system to concrete and steel – it continues to be touted around the world for its sustainability, seismic resistance, fire safety performance, visual aesthetic, and durability. But its most unique quality, especially as it relates to building in a COVID-19 era, is this: prefabrication.
What is prefabrication?
In mass timber construction, components are typically built off-site in a factory and then transported to the project site to be assembled – in some ways, similar to how a puzzle comes together. Since mass timber is significantly lighter in weight and more versatile than its traditional counterparts (like concrete and steel), it makes it the perfect candidate for prefabrication construction systems.
As has been made clear throughout the pandemic, developers and builders need to consider prefabricated construction options more seriously. Why? Because this approach can significantly cut down on project timelines and deliveries, while ensuring safer and less crowded construction sites. Here are some key ways that prefabrication in mass timber construction can help combat society’s biggest concerns with the spread of the coronavirus.
1. It lowers and removes on-site waste and traffic.
One of mass timber’s greatest advantages is its versatility. It can be manufactured into a variety of shapes, sizes, and configurations, and then applied in a wide range of building typologies.
Mass timber’s prefabricated nature means up to 75% fewer workers are required on-site at any one time. Since mass timber building components are delivered to the project site in their ready-to-assemble state, it makes piecing together the different parts less complex and quicker to install, thereby driving down labour costs.
Building with mass timber also requires up to 90% less construction traffic (inclusive of trucks delivering materials) compared to conventional builds. Again, this is mainly due to the fact that mass timber is lighter in weight and because its parts are prefabricated, thereby eliminating any excess waste of product that would otherwise be discarded throughout the construction process.
2. It reduces construction time.
Prefabrication in mass timber construction means that such buildings are roughly 25% faster to construct compared to the likes of concrete structures. Since the cross-laminated panels and glulam beams are manufactured off-site, all that needs to be done once the parts have been delivered to the construction site is a matter of assembling.
First Tech Credit Union in Hillsboro, Oregon was a model for technologically advanced construction. Harnessing VD&C technology, 3D modelling for fabrication, and CNC machining, the entire project was built virtually before fabrication even commenced. This ensured that the pieces, which were delivered to the site as a fully pre-fabricated kit of parts, would be assembled on-site without clashes, errors, or safety incidents.
Hand in hand with the benefits of prefabrication is the sustainability that building with wood achieves.
3. Mass timber reduces build emissions.
Using First Tech Credit Union as an example, the construction of that building avoided 1,622 metric tons (1,788 US tons) of greenhouse gases that would’ve been emitted through steel manufacturing and construction.
Wood also facilitates carbon sequestration – the process of absorbing and locking away carbon within itself for decades, if not longer. Referencing the First Tech Credit Union, the building sequestered 4,192 metric tons (4,621 US tons) of carbon. As a result of this sequestration, mass timber buildings have one-third of the greenhouse gas warming potential of concrete buildings, and nearly one-half that of steel buildings.
Further to that, once erected, a study that assessed the life cycle of building materials (in both warm and cold climates) found that the total life cycle energy emissions for wood buildings were 31% lower than comparable structures of concrete, and 26% lower than steel.
Finally, the North American softwood lumber industry utilizes some of the most productive, sustainable, and cost-competitive timberlands in the world. This sustainably managed wood basket is a renewable resource for the mass timber industry to access that further builds upon its positive environmental impact over concrete and steel.
Mass timber opens up the opportunity to build in a more conscious way. Looking ahead at an uncertain future, the building industry must consider mass timber options for their prefabricated nature – which alleviates site congestion, reduces build time, and contributes to clean and safe worksites – but also for their ability to provide beautiful, sustainable places for people to live, work, and play.