MODERN MASS TIMBER
The growth of interest and implementation of mass timber, including the use of innovative materials such as Cross Laminated Timber (CLT), is definitely on the rise. This movement originated in Europe and eventually spread to Canada, Australia, New Zealand and now Japan and the United States. But mass timber construction is not new. In the Northwest, all we have to do for evidence of this is look around at the old, turn-of-the-century warehouse buildings, constructed up to 9 stories tall, almost entirely of large old growth beams and columns, along with the original nail laminated timber (NLT) flooring.
The revitalized interest in mass timber construction is not singularly driven but rather a combination of the availability of new mass timber products such as CLT, a focus on sustainability and renewed appreciation of the aesthetic. Most importantly mass timber has been proven to be cost competitive under the right conditions. But challenges remain. Mass timber has been largely forgotten by modern codes and regulatory hurdles must be overcome before implementation on a larger scale is realized.
So how did I get thrust into the middle of the mass timber movement? The answer really is right place, right time, right opportunities, coupled with the background, experience and passion to want to make modern mass timber projects a reality.
I was born in Roseburg, Oregon, just up the road from D.R. Johnson, the first domestic producer of APA certified structural grade CLT. As an Oregon Native, I grew up with a strong appreciation of the outdoors and the forests around me. Our family vacations were entirely by car, which meant many of visits to the National Parks of the West. It was on these visits that I first gained my appreciation of mass timber construction through the scale and craftsmanship of the great lodges at Timberline, Lake Quinault, Mount Rainer, Yellowstone, Glacier, Yosemite, among others. It was also on these trips that a budding interest in a future as an architect began, including sketching up my own lodge concept.
My life journey would eventually lead me south to Cal Poly San Luis Obispo, where I joined the Architectural Engineering program. I never lost my love and appreciation for Oregon though, much to the annoyance of my closest friends and future wife (apparently I talked about it a lot?). The Architectural Engineering program turned out to be the perfect fit for me as it allowed a continued link to architecture while developing my technical creativity, which is frankly much stronger than my artistic creativity. It was here that I learned the value and importance a creative engineer can bring to achieving an architect’s vision and ultimately a beautiful built project. Unlike a lot of universities, Cal Poly also provides strong classes in wood engineering and design. An extended internship / part-time job at a local engineering firm also gave me my first practical experience, on scale which allowed me to own a project and coordinate directly with architects and contractors.
Upon Graduation from Cal Poly, I headed further south to UC San Diego, to complete my graduate studies in the Structural Engineering program. It was here that I strengthened my technical background, particularly in advanced seismic design, to go with the very practical approach of Cal Poly. The combination of this educational experience has served me well.
TIME FOR THE REAL WORLD
In 2005 I decided to start my gradual journey back north taking a job with KPFF in San Francisco. San Francisco is at the center of seismic design development in the US with a vibrant and engaged engineering community. Through the strong guidance at KPFF and involvement in the Structural Engineering Association of Northern California I continued to gain experience in advanced seismic design. Volunteer efforts with FEMA Urban Search and Rescue, Engineers without Borders, AIDG, and completing post-earthquake building inspections in Haiti, also helped reinforce the importance of a properly designed, detailed and constructed building.
NEW ZEALAND BOUND
Oddly, enough it was a decision by my wife and I that it was time to move back to Portland that helped lead us half-way across the world to Christchurch, New Zealand. Following the Canterbury earthquakes in 2010 & 2011 there was strong need for qualified engineers to complete post-earthquake damage assessments and help with the rebuild process. I was always intrigued by the possibility of living and working overseas, and since we were planning on pulling up roots anyway I jumped at the opportunity to work with Holmes Consulting, the premier structural engineering firm in New Zealand. The experience was invaluable, a virtual structural engineering laboratory where you can observe firsthand the performance of buildings design and constructed in a similar fashion to those in the US (as opposed to Haiti). The general consensus was that vast majority of buildings designed to modern codes met their “life safety” performance objective. At the same time the central business district was cordoned off for two years and more than a 1000 buildings had to be demolished because they were uneconomical to repair. As a result public entities, engineers and the general public began to ask the question, should we be expecting better performance out of our building stock? The answer to many, was yes.
As a result, the idea of “low damage” or resilient design really began to take off. As the New Zealand building code is performance based, rather than prescriptive based as in the US, engineers had the flexibility to incorporate the latest in research to come up with some truly innovative designs. Strangely enough, one of the most intriguing low damage structural systems being implemented, Post-Tensioned Rocking Walls, was imported from the US. The research and testing for this system originated through the PRESSS at UC San Diego, which resulted in the system being codified through ACI ITG-5.2-09 “Requirements for Design of a Special Unbonded Post-Tensioned Precast Shear Walls”. I was lucky enough to work on the design of one project utilizing this system during my time in New Zealand.
It was another life change in 2013, the birth of our daughter, which led us to the tough decision to leave New Zealand and return home. Upon our return I was lucky enough to rejoin the KPFF family in Portland. I was immediately amazed at the breath and quality of projects the Portland office has had the opportunity to work on over the years. It didn’t take long for a few of these projects to start coming my way.
In late 2013 KPFF received an invitation to attend a workshop in Seattle on Engineering Resilient Tall CLT Buildings in Seismic Regions. Based upon my recent experience in New Zealand it was decided I should go. The workshop was set up by an NSF funded team of researchers headed up by Professor Shiling Pei from Colorado School of Mines. The goal of the workshop was to gather together stakeholders and determine what type of buildings could be economically constructed out of CLT and what the barriers were to widespread implementation.
On the economic side it seemed the real sweet spot for mass timber construction to compete with concrete and steel construction was in the mid-rise range of 7 to 12 stories. Two of the biggest challenges identified for mass timber buildings of this height were the technical and regulatory hurdles around fire and seismic. On the seismic front, one of the most promising resilient lateral systems being discussed was tall post-tensioned rocking walls. While in New Zealand I began to see timber used in some new and innovative ways, including as post-tensioned rocking walls, but not at this scale. Based on other research, including research KPFF is collaborating on, I knew the concept of tall rocking walls was possible.
At the same time I got the opportunity to start working on the Rocky Mountain Institute’s new Innovation Center (RMI) in Basalt Colorado with ZGF Architects. This is a project that is intriguing from a number of angles, most notably for being one of the most energy efficient buildings in the country. CLT was originally considered for the floor framing because RMI was intrigued at the CLT’s natural embodied carbon and the ability to be manufactured from beetle kill pine, an endemic in Colorado. As there wasn’t a manufacturer in Colorado, CLT was discounted in lieu of a raised access floor and T&G decking over glulam beams and columns. As the design developed we were tasked with reducing the overall floor-to-floor height without compromising the overall modern timber aesthetic. To do so we brought CLT back in the form of a unique two-way floor system with integrated mechanical chases. The switch reduced the overall floor assembly depth from approximately 4 feet to a little under 20”. This resulted in less exterior skin, better energy performance and enhanced natural lighting by removing glulam shadow pockets. We were also able to specify British Columbia beetle kill pine for demonstration purposes.
The RMI project ended up being the perfect project for me as I was already comfortable working outside the prescriptive bounds of the code from my time in New Zealand and it allowed me to foster a growing interest in mass timber construction. Since this introduction, I have kept up to date with the latest in CLT research, traveling around North America to attend seminars and workshops and conduct site visits to built projects and manufacturing facilities. KPFF also joined in joint research endeavors with academia and knowledge sharing programs with Woodworks and SEAO.
Following the RMI, I have had the opportunity to work on two other exciting projects with Lever Architecture in Portland. The first is Albina Yard, a four story office building utilizing CLT floors. This is the first permitted project utilizing CLT floors in the State of Oregon, and was largely made possible through the Oregon Statewide Alternate Method 15-01 Cross Laminated Timber Provision. The second is for Framework, the West Coast Winner for the USDA Tall Wood Building Competition. These and a number of new and exciting mass timber projects are in the works. We hope to be able to reveal them soon.
Part 2: Tall Wood – Challenges & Opportunities…..to follow« Back to News