Southern Perspective

The official blog of the Southern Group of State Foresters

Dan Chappell

Mass Timber as an Emerging Building Material for the 21st Century

October 21st, 2019
Forest Inventory & Analysis Coordinator
Alabama Forestry Commission

Although most people probably do not think about ‘high-tech’ and innovation when they think about lumber and forest products, the fact is that our field is constantly in a state of change as advances in genetics research, automation, efficiency gains, and more keep the Southeast well positioned to compete effectively in a global marketplace. One example of new technology that has come home to Alabama – International Beams in Dothan – is the emerging industry for Mass Timber, which is a more general term for cross laminated timber (CLT) and associated products such as dowel-laminated timber (DLT), glue-laminated timber (glulam), and others.

Although this technology is native to Europe, where it has been in place for roughly two decades, it has taken time for us on this side of the Atlantic to climb on board. And even in North America, the first manufacturing facilities for mass timber were located in the Pacific Northwest and in Canada, where the tree species are much different from what we are used to seeing here. The question was, would our Southern Yellow Pine (loblolly, longleaf, shortleaf, and slash) provide lumber suitable for conversion into mass timber? With ongoing research assistance provided by the Forest Products Development Center at Auburn University, the answer arrived at by the International Beams company was “Yes, southern pine is a fit for our product.”

What, exactly, is this product? Let’s look at cross laminated timber. You have probably held a sheet of plywood before. You are picturing thin sheets of wood pressed together and held in place by an adhesive. CLT works on a similar principle, but the panels are created using dimension lumber. To maximize strength, the lumber is layered perpendicular at 90o angles, thus providing a strength axis no matter where forces are being applied. CLT panels can consist of three, five, seven, or even nine layers, depending upon the load-bearing strength needed, and the adhesives are state of the art. In fact, testing has revealed that the adhesive bonds are stronger than the wood itself.

International Beams (IB), after a careful search for a southern hometown, selected to re-purpose an unoccupied existing manufacturing facility in Dothan. The site was a perfect fit, with proximity to major potential markets in Florida, Atlanta, and beyond. Major IB-manufactured projects are the First United Bank of Fredericksburg, Texas, and the Snow Family Outdoor Fitness and Wellness Center at Clemson University, highlighting the advantages of being able to serve the South from a central location.

You might be thinking that you have never seen this product on sale at your lumber supply store, and you would be correct. Panels are not currently sold to the general public. One of the amazing things about CLT is that when architects design a building out of this material, they use a computer to design the placement of all wiring and plumbing. At the factory, these design plans are then implemented in their computer systems. Each individual panel passes through a cutting-edge Computer Numerical Control (CNC) machine, which preps each panel with the appropriate openings. When it comes time to load the delivery truck, each panel is packed in reverse order of when it will be used on the construction site. At the construction site, a small crew of trained individuals essentially follows the instructions and assembles something that resembles a LEGO house, with no need to drill holes for wires and pipes. Did I mention these structures can be up to 18 stories tall? I have not seen one of these high rises first hand, but the pictures make you think that you are viewing a building from the future.CLT Sample_cropped

So, with all these positives, and with the Southeast’s only manufacturing facility, why are we not seeing more mass timber projects pop up? There are a few reasons. First is cost. Mass timber can be cost competitive with steel and concrete in large buildings. Do not look for mass timber to replace traditional wood framing in single-family homes or even apartment buildings any time soon. There is a learning curve involved for building contractors as they learn the advantages of this material. Up until now there has been a tendency to ‘price in’ this uncertainty. With experience, this will change. Although the upfront cost of materials may be marginally higher for mass timber as compared with traditional materials, there are the twin advantages of being able to construct a building in a shorter time with a smaller construction team. If anticipated labor shortages in the construction trades continue and even intensify, the advantage of being able to build faster with fewer workers will become magnified. The less time spent building a hotel, the sooner the paying customers can start to check in.

A second reason for not seeing more mass timber projects is professional knowledge. It simply takes time for architects and builders to re-train themselves to be able to produce their work using a different medium with different properties and different methods. However, this knowledge is being diffused. There is now a 57-hour construction course being offered in Chicago where construction teams not only learn about mass timber, but also acquire hands-on experience building ‘practice’ CLT structures. Learning how to correctly use the multiplicity of joints is key to this type of construction. Universities are now including mass timber in their architecture curriculums. There is a small number of ‘champion’ architects who are now designing prestige buildings to be built out of mass timber. That number is growing, but the reality is that the majority of practicing architects have not worked with this material and need additional training to become proficient.

 

First United Bank building at Fredricksburg, Texas. First finished building made with Southern Yellow Pine from International Beams (IB) in Dothan, Alabama.
First United Bank building at Fredricksburg, Texas. First finished building made with Southern Yellow Pine from International Beams (IB) in Dothan, Alabama.

 

A third major obstacle involves building codes. The country is covered by a patchwork of differing local building codes. Simple lack of guidance in the codes for mass timber has slowed adoption. Research has been conducted, and hard data has been collected on mass timber’s structural and fire resistance characteristics. Additionally, as this technology is moving out of Europe and into North America and Australia, it is gaining its own dedicated section in the International Building Code (IBC). The next revision of the IBC is due in 2021, with proposed changes that will allow for wooden buildings up to 18 stories. The tall buildings that have been built up until now rely on local code exemptions, or in the case of Oregon, on laws passed specifically to encourage mass timber construction of tall buildings. With publication of the updated IBC in 2021, and as localities move to adopt the new standards as their own, more and more jurisdictions will be able to permit these medium and tall wooden structures in the normal course of business. This process has been slow, but it is moving ahead.

If, after reading this article, you have questions or interest in pursuing a mass timber project of your own, do not reach out to me. I am not the expert. Fortunately, there is an organization of engineers you can contact, who seek the success of mass timber. And better than that, the one-on-one project support they offer is provided at no cost. The organization is WoodWorks, and its regional representative is Jeff Peters, PE. Their site at www.woodworks.org is the premier resource for learning about mass timber and what needs to happen to carry a project from dream to reality. While there, you can view the gallery, with amazing images of finished mass timber projects and works in progress.

 

CLT info graphic

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