The family of products that encompass mass timber –including Cross-Laminated Timber (CLT), Glue-Laminated Timber (Glulam), and Mass Plywood– is increasingly becoming a viable construction alternative for the AEC industry. Timber has been a structural material for thousands of years, but these engineered wood products have broadened the field of options and provided a solid basis for architectural designers to work with, expanding upon their range of materials and finishes.
Mass timber construction has many benefits from quick and quiet prefabricated installation to a lower carbon footprint when made from sustainably sourced wood. One other benefit of a product like CLT is its overall strength to weight ratio, making it lighter than many materials but structurally as strong (for example, one cubic meter of CLT weighs 400 kg and one cubic meter of reinforced concrete weighs 2.7 tons). One American architect at the forefront of mass timber innovation is Thomas Robinson, a founder of LEVER Architecture.
LEVER Architecture: Leading in Wood Innovation
Thomas Robinson has lectured across the US, Europe, and South America on the merits of Mass Timber, and LEVER has received over $1 million in grants to pursue research and testing. They have completed numerous mass timber projects.
Recent projects by LEVER include the Meyer Memorial Trust, a headquarters building that utilizes Mass Plywood panels. To Robinson, engineered timber is a tool that architects and construction professionals can use to produce more sustainable solutions.
'When we talk about the future of wood construction,' Thomas Robinson said, 'in many ways, we’re also talking about the future of forests.'
The firm often uses Vectorworks Architect for conceptual design drawings and the Redfox Commons was fully designed, documented, and permitted with Vectorworks.
As LEVER renovated Redfox Commons, a historic heavy timber industrial structure in Portland, Oregon, a portion of the existing wood was reclaimed and repurposed to create glulam columns and beams to create a new connecting atrium structure. The rest of the building utilized other common wood products including 4x6 tongue and groove decking for new second floors, and 2x12 LVL framing for full height new exterior walls. Glue-laminated columns and beams were used to create a new second floor in east and west buildings and topped with the 4x6 tongue and groove decking, a ½” of OSB, and a lightweight gypcrete topping slab for level office spaces.
Another of LEVER’s projects, the Oregon Conservation Center, reimagines a building first constructed in the 1970s; the interior was siloed, dark, and lacked proper conference areas. Its exterior was characterized by aging metal. In effect, the building didn’t represent the organization or its needs. LEVER’s renovation and addition to the building aimed to address these concerns and additionally provide a highly sustainable headquarters, one fitting for an organization like The Nature Conservancy whose primary goal is conservation.
LEVER created three distinct outdoor environments that each mimic protected landscapes in Oregon. The building’s Juniper siding and Cedar decking were sustainably harvested from the nonprofit’s conservation sites. The building includes a new addition for events and collaborations with partner organizations. The addition is one of the first structures in the US built with domestically fabricated CLT panels that are FSC certified.
Cross-laminated Timber in the Adidas North American Headquarters
The expansion of Adidas's North American headquarters is one of the largest CLT projects in the US. Robinson said LEVER sustainably sourced almost one million feet of timber from Oregon to complete the project.
The site’s southmost building sits on top of an existing parking garage and features a steel frame core complementing the glue-laminated column and beam structure with CLT floor decks. While the weight of CLT resulted in a lighter structure, its existence was not entirely possible only because of CLT. The building’s central frame was constructed in just three or four days, Robinson said, in large part because the timber is prefabricated.
The north building utilized a hybrid structural system made from pre-cast concrete columns and girders with glulam beams and CLT panels. These were regionally sourced and transported in stacks on truck beds for construction.
Cross-laminated timber is one of the ways the AEC industry is continuing to evolve towards alternative building methods, and its popularity is growing:
'When I’ve done polls asking what about timber as a building material appeals to people,” Robinson said, “the aesthetics, the visual appeal, is always the number one answer.'