Posts tagged with "cross-laminated timber":

Placeholder Alt Text

2017 Best of Design Awards for New Materials

2017 Best of Design Award for New Materials: Indiana Hardwood Cross-Laminated Timber Project Designer: IKD Location: Columbus, Indiana The Indiana hardwood cross-laminated timber (HCLT) project is the first commercial pressing of HCLT and the first use of HCLT in a built project in the United States. IKD aspires to create a new timber product by upcycling low-value hardwood sawn logs that are extracted from Indiana forests. Indiana’s largest cash crop is hardwood, but over 55 percent of each log processed is of low value. The firm set out to demonstrate how low-value hardwood can be used to create high-value HCLT, which can then be used as the primary structure for buildings. This process has the potential to initiate a cascade of effects: positive job growth in rural forestry and manufacturing, hardwood lumber market expansion, forest land value increase, and improved forest management practices. HCLT offers numerous benefits over softwood, including superior mechanical properties, material volume savings, and increased fire resistance. “The use of hardwood in mass timber is appealing on many levels. Its added strength and durability over softwoods makes it ideal for exterior applications.” —Nathaniel Stanton, principal, Craft Engineer Studio (juror) CLT Fabricator: Smartlam Timber Engineers: Bensonwood General Contractor: Taylor Brothers Construction Hardwood Material Supplier: Koetter Woodworking Grant Funding: United State Forest Service Wood Innovation Grant
Placeholder Alt Text

2017 Best of Design Awards for Office & Retail

2017 Best of Design Award for Office & Retail: Albina Yard Architect: LEVER Architecture Location: Portland, Oregon

Albina Yard is the first building in the United States made from domestically fabricated cross-laminated timber (CLT). This new 16,000-square-foot speculative office building utilizes mass timber construction, with a glue-laminated timber frame and CLT panels manufactured and prefabricated in Riddle, Oregon. The project’s primary goal was to utilize domestic CLT in a market-rate office building that would pave the way for broader adoption of renewable mass timber construction technologies in Oregon and the United States. The design approach reflects a commitment to this sustainable technology by developing an architecture focused on economy and simplicity, material expression, and the careful resolution and integration of all building systems to foreground the beauty of the exposed Douglas fir structural frame.

“As a structural strategy, mass timber is very similar to a cast-in-place concrete structure in terms of layout and function of its individual elements. The main difference is the character and humaneness of the remaining spaces.  It is very well-suited for this type of use.” —Nathaniel Stanton, principal, Craft Engineer Studio (juror) General Contractor: Reworks Structural Engineer: KPFF Consulting Engineers CLT Supplier: DR Johnson Lumber CNC Routing: Cut My Timber   Honorable Mention Project: Cummins Indy Distribution Headquarters Architect: Deborah Berke Partners Location: Indianapolis, Indiana This new office building reinforces an active pedestrian experience that is connected to downtown Indianapolis and its parkland. The unusually slender floorplan and high ceilings provide abundant natural daylight for every space and minimize reliance on electricity. A high-performance “calibrated” facade and an integrated system of fins and shades limit heat gain and increase thermal comfort.   Honorable Mention Project: Zurich North America Headquarters Architect: Goettsch Partners Location: Schaumburg, Illinois Located on a 40-acre expressway site in suburban Chicago, the North American headquarters of the Swiss Zurich Insurance Group reflects the company’s global reach and commitment to sustainability. Composed of three primary “bars” that are offset and stacked, the arrangement creates unique spaces for collaboration, opens views of the surrounding landscape, optimizes solar orientation for amenities, and provides programmatic flexibility.
Placeholder Alt Text

Microsoft reveals renderings for its new Silicon Valley campus upgrade

Microsoft has gone big and broken ground on its new Silicon Valley headquarters, with a sustainability-minded plan to modernize its Mountain View, California outpost. The 32-acre campus might seem small when compared to the company’s sprawling, 500-acre flagship location in Redmond, Washington, but Microsoft’s pursuit of a net zero non-potable water certification under the Living Building Challenge will make them the first tech company to totally reuse non-potable water. The redevelopment plans come as WRNS Studio replaced SOM early last year as Microsoft’s designers of choice. The redevelopment is leaning hard on a green modernization, with Microsoft pursuing LEED Platinum certification for all of its new buildings, committing to the WELL Building standards for the interiors, and integrating cross-laminated timber (CLT) throughout all of the new buildings to cut material usage. In trying to meet their water-use reduction goals, and acknowledging California’s limited groundwater availability, the campus will feature rainwater catchments and an on-site wastewater treatment plant so that drinkable water can be recycled for other uses. Because the campus is next to Stevens Creek, the tech giant is also introducing a 4-acre, occupiable green roof solely planted with native species. Rooftop solar panels will also help cut the campus’s energy usage, while the buildings will let natural light in through their uniformly large windows. Not to be outdone by the main, Seattle-adjacent campus, the project will also include an underground parking garage topped by a soccer field and a new athletics facility, while returning the former parking lots to nature. Besides modernizing the office space of their 2,000 San Francisco Bay Area-employees, the new campus will feature a renovated dining hall, new theater, conference center, and a “Microsoft Technology Center.” Microsoft has provided a full fly-through video of their plans below. The new Mountain View campus plan increases the existing 515,000-square-foot campus to 643,000 square feet, and comes amidst the recent opening of Apple’s new space-aged campus nearby. Similarly, Microsoft's renovation of its main headquarters in Redmond, announced at the same time as its Silicon Valley campus, feels like a direct response to Amazon’s city-hopping HQ2 plans. Microsoft's Silicon Valley campus is on track to re-open sometime in 2019.
Placeholder Alt Text

New timber research finds exciting potential in steel and concrete composites

With mass timber projects on the rise around the United State, Skidmore, Owings & Merrill (SOM) and Oregon State University (OSU) have partnered to produce two new reports on how timber buildings can overcome their technical limitations by integrating steel and concrete. The new composite systems being proposed would allow timber construction to rise higher than before, with longer floor spans. The OSU Testing Report, released earlier this month, looked into the possibility of combining cross-laminated timber (CLT) floor systems with a concrete topper, to improve the strength of the flooring as well as lengthen its span. To accurately represent real-world conditions, the SOM team first drew up plans for a “typical” 11-story residential building and indicated where the wood columns would normally be. With the floor span determined, the CLT flooring was stress tested for load, bending, cracking and shearing, before and after the application of a concrete slab. A 2.25-inch thick concrete layer was applied over a 6.75-inch thick CLT floor for the experiment. After testing smaller, individual sections, an eight-foot-by-36-foot full-sized mockup was created and subjected to load testing, only failing after engineers applied eight times the normal service load, or around 82,000 pounds of pressure. One complicating factor is that CLT can be charred for a higher fire rating at the expense of its strength, and any real-world application of CLT would need to be thicker than in testing conditions. Still, the results are a promising first step to increasing floor spans in timber buildings as well as improving their acoustic properties. The second report was produced in conjunction with the American Institute of Steel Construction (AISC) and examined how steel framing can best be integrated with timber floor systems. Because steel framing can span much greater distances than timber with smaller columns, and because CLT is lighter than concrete, a building that uses both should get the best of both worlds. In SOM’s modeling, this combination model was equally as strong as a steel and concrete building while offering window bays of the same size as a typical residential building. Ideally, high-rise timber construction of the future would combine both of these techniques, as the concrete slab topper adds extra seismic protection. With timber construction offering the potential for more sustainable, durable and quickly assembled towers, hybrid research could be a stepping stone towards bringing mass timber construction into the mainstream. All of SOM’s timber research reports can be found here.
Placeholder Alt Text

Arbora housing complex in Montreal points to the future of timber construction

This is an article from our special November timber issue. Comprising three eight-story buildings totaling just shy of 600,000 square feet, the Arbora Complex near downtown Montreal is one of the largest mass timber projects in the world. The notability of this project is not just its size, but its ability to be a competitive, marketable, environmentally responsible alternative to increasingly affordable steel and concrete construction—an ability we might not associate with mass timber structures. The $130 million project offers 434 units, 130 of which are rental. According to U.S. Market Development Manager Jean-Marc Dubois at Nordic, a Quebec-based company that, among other services, supplied wood for the project, “The market in Montreal is more suppressed than Vancouver and Toronto. To be able to build means you must have a design that is viable and efficient—something that brings value to the developer. There’s a lot of press surrounding high-rise wood construction, but Arbora shows there’s a place for affordable, viable mid-rise construction.” Arbora involves cross-laminated timber (CLT), composed of layers of dimensional lumber stacked perpendicularly and glued together to create structural panels. CLT panels are typically made of layers of three, five, or seven, and, because they offer two-way span capabilities, can be used for floors, walls, and roofs. The result is a material that is lightweight, strong (up to seven times the strength of concrete), efficiently shipped, and less labor-intensive than its steel and concrete counterparts.
“With mass timber structures, you can use less employees and get more work done,” said Dubois. “There’s a shortage of skilled labor across North America, so the fact that you can raise structures with considerably less skilled employees is very critical. Typically we operate with as few as four to six tradespeople on a jobsite. The output per person is much greater.” These benefits come with a cost, however: increased upfront coordination and design time. Engineered wood components are designed, optimized, cut to millimeter precision, and then shipped to site for assembly. Dubois reports that Nordic is involved on multiple fronts of mass timber projects like Arbora, coordinating design, engineering, fabrication, construction sequencing, and regulatory parameters. “This is one of the things that distinguishes Nordic,” he said. “There’s a tremendous amount of involvement and engagement with our team that you don’t necessarily see as you’re looking at the construction process. We’re taking an active role in the design process, in addition to sitting in meetings with local authorities.” The key to Arbora’s commercial success in a competitive housing market is design efficiency, and an acknowledgement of the inherent structural properties of CLT from the outset of a project. “There are efficiency gains in replication,” Dubois said. The project was organized around a 20-foot grid, an ideal structural span and shipping dimension for the beams and panels. The consistency of the grid allowed an efficient manufacturing process, and abbreviated on-site assembly time. Early adopters of CLT in North America have tended to be more custom projects like schools and sports venues, but Dubois sees demand for mass timber shifting into commercial real estate, namely office workplace typologies, where the unique look of a wood structure can offer differentiation in the marketplace. Mass timber adoption in the United States has lagged behind that in Canadian markets. Dubois attributes this to a number of factors including the litigious nature of the United States, and the tendency of Canadian authorities to be receptive to performance-based design. “In Quebec, we don’t promote one building material over another, so we have to make a market against steel and concrete, which is exceedingly inexpensive,” he said. “We have to be economically viable and prove we are meeting the same structural and safety requirements that other systems must abide by. “Performance-based design typically runs into more red tape in the United States,” he continued. “I think it’s a fear of the unknown. This has led the American Wood Council, the U.S. Department of Agriculture, and the wood industry to promote the tall wood agenda, to try and get coded options so that it is prescriptive as opposed to alternative means and methods.”
Placeholder Alt Text

Congress gears up for a fight over mass timber legislation

This is an article from our special November timber issue. The battle over the 2017 Timber Innovation Act is gaining momentum in Washington, D.C., where two new Senate sponsors and four new Congress members have signed on to it since this past May. The pending legislation would provide funding for research into innovative wood materials and mass timber structures above 85 feet. The bill’s proponents are hoping that it will be an impetus for transforming cities and towns across the country with a bevy of mid-rise and high-rise mass timber buildings. “I am very impressed with the large cross-aisle support,” Chadwick Oliver, director of Yale University’s Global Institute of Sustainable Forestry, said. “You have Bruce Westerman, a Republican congressman from Arkansas and Peter DeFazio, a Democrat from Oregon who has been on the side of environmental groups. This looks like a bill that is quite serious about moving forward.” However, the concrete and steel industries are vigorously lobbying to derail the legislation, and have established a website called Build with Strength that contains a detailed critique of the new generation of wood buildings. “It is a piece of legislation that props up one industry over another and we think that it is misguided and dangerous,” Kevin Lawlor, a spokesperson from Build with Strength, said. “We don’t think that it is safe in three-to-five story buildings, and we don’t think that it is safer in taller buildings.” The wood products industry, the U.S. Forest Service, and other advocates claim that technological advances make the new generation of tall timber buildings more fire resistant. In fact, according to Dr. Patricia A. Layton, director of the Wood Utilization + Design Institute at Clemson University, that is because of the way it chars in a fire: By insulating its interior, an exposed wood beam can actually be structurally stronger than a steel one. “Steel loses its strength at a lower temperature than does wood,” she explained. “If you expose concrete or steel it is combustible, and it does feel the effects of fire.” Many of the act’s supporters say that allowing buildings to be built from wood technologies such as cross-laminated timber (CLT) will result in a host of economic and environmental benefits. Most of the Timber Innovation Act’s sponsors hail from states where the wood industry is struggling to recoup from the recent housing downturn and also suffering from the decrease in demand for paper that is a result of the increasing digitalization of the economy. “A big part of the innovation act is having the U.S. Forest Service work to expand markets and attract business to heavily forested states, particularly those that have a major timber industry,” said Andrew Dodson, vice president of the American Wood Council, who notes that the U.S. Timber Innovation Act is a way to help jumpstart a sagging wood-products industry. “Mills are running at much lower capacity,” he said, “two shifts versus three or four—we want to put more mill jobs back in place.” However, some in the mass timber industry say that the Timber Innovation Act will be of limited utility until building codes are changed to allow for the use of CLT. “The code issue is more critical than the Timber Innovation Act,” Jean-Marc Dubois, director of business development for the Montreal-based Nordic Structures, said. He believes that New York City’s restrictive building codes have helped stall progress on tall timber, pointing to the wooden skyscraper designed by SHoP architects that was killed earlier this year as an example. Even though the 2015 International Building Code (IBC), which New York City has not adopted, allows for the use of CLT, Dubois said that building departments throughout the country haven’t updated their codes to allow for the use of CLT. Having the SHoP project, which received a lot of publicity, fail to get built was a major setback for the industry, according to Dubois. “New York City had the ability to be a real-world leader with timber innovation,” he said. “It was disappointing.” A $250,000 grant from the U.S. Forest Service’s Wood Innovations Grant program helped Yugon Kim of Boston-based IKD develop what he believes is the first hardwood CLT structure in the U.S.: An outdoor sculpture in Columbus, Indiana, which consists of a series of ascending arcing forms. Congress is not the only place in Washington where the merits of tall mass timber are being explored. Steve Marshall, assistant director at the U.S. Forest Service, has been working with the International Code Council to develop standards for the use of CLT. In addition, the U.S. Department of Defense has been conducting blast tests with CLT to determine whether it is an appropriate material to use on its bases. Marshall said there are other potential sources for government support for CLT projects aside from direct funding from the Timber Innovation Act. In the third week of October, his agency will be releasing a new round of grants of up to $250,000 under its Wood Innovations Grants program. Next year, the Forest Service is planning on making $8 million available under the same program, and applications will be due by mid-January. One of the most notable examples of how government funding can play a difference is with LEVER Architecture's innovative design of the 12-story (148-foot-tall) Framework building under construction in Portland, Oregon, which will be the first wood high-rise in the U.S. A $1.5 million U.S. Tall Building Award sponsored by the U.S. Department of Agriculture helped fund the seismic and fire-safety tests that enabled it to pass muster with Portland building department officials. Thomas Robinson, principal of LEVER Architecture said that the concrete and steel industries shouldn’t be worried about losing market share because in the future most tall timber structures will be hybrids that include concrete and steel as well as wood. “We need to look at each material for its appropriate purpose,” he said.
Placeholder Alt Text

Is mass timber really sustainable?

This is an article from our special November timber issue. We like to blame a lot of things for climate change—namely coal and cow farts—but if we were to search for a worthy scapegoat, architects might end up looking in the mirror. The building sector is responsible for 44.6 percent of U.S. carbon dioxide (CO2) emissions. And, with an estimated 1.9 trillion billion square feet to be built in the next 33 years, those emissions will not subside without significant intervention. On the flip side, for architects anyway, this means the power to reduce carbon emissions is quite literally in your hands. “No designer—I think—wakes up and says, ‘I want to make the world worse today,’” William McDonough, architect, designer, and sustainable development leader said. “To make the world better, that’s our job.” Identifying successful ways to build sustainably can be difficult in a haze of greenwashing and checklist-style certifications, but many environmental experts, architects, and scientists are looking to mass-built timber as a reliable way to reduce carbon and fossil fuel output. A recent study, “Carbon, Fossil Fuel, and Biodiversity Mitigation with Wood and Forests,” stated that using wood as a building-material substitute could save “14 to 31 percent of global CO2 emissions and 12 to 19 percent of global FF [fossil fuel] consumption by using 34 to 100 percent of the world’s sustainable wood growth.” Building with timber reduces the overall carbon footprint in several ways. First, wood is a renewable resource, and growing a tree is a low-impact method of production (i.e. it uses photosynthesis rather than a plethora of machines). Second, trees are grown in abundance all over the United States and don’t need to be imported from abroad, reducing the amount of energy expended on shipping. “Right now we harvest less than half of what we could and still be well within the threshold of sustainability,” Kathryn Fernholz, the executive director at Dovetail Partners, an environmental nonprofit, explained. “That’s not the same in every single scenario, but in general in the U.S., we have an abundance of wood.” Third, and perhaps counter-intuitively, many environmentalists believe that harvesting trees allows forests to become more efficient at carbon sequestration. The logic is simple: When a tree is harvested, it stores carbon, then when another tree is planted in its place, it also will store carbon, making that plot of land’s carbon sequestration infinitely multipliable as trees are planted, grown, and harvested. “There is a widely held belief that cutting down trees is bad and causes loss of forest, but a strong market for wood products would cause us to grow more forests,” Fernholz said. “The vast majority of deforestation is land conversion, using the land for something else like development or agriculture. We know what resources we have and we monitor them and adjust. Forestry is not in the same place it was a hundred or even fifty years ago when deforestation was an issue.” While that stance of de-and reforestation is under debate among environmental experts, across the board, timber is generally a more sustainable building material because it is a renewable resource (provided that responsible forest practices are used). This includes the energy consumed to produce cross-laminated timber (CLT) in factories, which have a carbon emissions advantage over steel because the wood does not need to be heated over 2,700 degrees Fahrenheit like steel or concrete—in fact, unless the wood is kiln dried, heat isn’t need at all. Although embodied carbon is typically measured per building, because different amounts of each material are used in different scenarios, Wood for Good, a campaign by the timber industry to promote the material, claims that a ton of bricks requires four times the amount of energy to produce as a ton of sawn softwood (wood used for CLT); concrete requires five times, steel 24 times, and aluminum 126 times. “Reporting carbon emissions for wood includes a range of different assumptions and methods,” explained Kathrina Simonen, an associate professor of architecture at the University of Washington and director of the Carbon Leadership Forum. “So sometimes it ends up negative and sometimes it ends up positive. It can be confusing.” She is optimistic, however, that research is close to resolving the differences. Responsible forestry practices are already underway, with harvest occurring on long rotations so that the forest has time to regenerate itself and care can be taken to avoid removing other plants, roots, and branches in the process. Lastly, “Wood can be a durable good, as we've seen in ancient wooden buildings like the Temple at Nara, Japan [originally built in 745 AD and rebuilt in 1709],” McDonough said. “In [wood’s] history, it is often put into a cycle of use and reuse that can take it from large numbers to smaller and smaller [components].” Its ability to withstand centuries and to be disassembled and then reassembled into other buildings and furnishings keeps it out of the landfill and in a perpetual cycle of use until it can ultimately be returned to the environment in some form. Although well over 90 percent of one-to-three-story residential buildings are already wood-built, there are only a handful of mid-rise and tall timber buildings across the United States, a result of building codes that often prohibit timber-built structures larger than four to six stories. However, thanks in part to innovative wood products, including CLT, nail laminated timber (NLT), and glue laminated timber (glulam), wood construction can be used in buildings as tall as 40 stories. A study by consulting and engineering company Poyry and the New England Forestry Foundation shows that the greatest potential for timber-built is in mid-rise (six to 14 story) buildings, as it also tends to be more economical to build with timber at that scale. According to the Soft-wood Lumber Board, over two-thirds of the square footage in the mid-rise sector could be made with mass timber. These statistics combined, in addition to the taller structures that mass timber can create, have the potential to make a sizable dent in our CO2 and fossil fuel emissions. Like virtually everything in architecture, though, it is all in the details; for timber to be sustainable it has to be done correctly, from responsible forestry practices to environmentally safe glues and binders to craftsmanship and the design itself. “It is tremendously exciting. Building with wood creates diverse opportunities—there are different species and materials that all can work,” Fernholz said. “However, it is important to recognize that some things can come from wood, but nothing replaces good design and planning.”
Placeholder Alt Text

Cross-laminated timber could lead a mid-rise revolution

This is an article from our special November timber issue. Engineers specializing in cross-laminated timber (CLT) see its future less in boutique prototype towers, requiring case-by-case demonstrations for approval, than in a meat-and-potatoes mid-rise market. While, according to Colorado State University's John van de Lindt, “some of those pioneering early CLT buildings are really almost like a partial R&D project in disguise,” he and colleagues predict that the field's maturation depends on the incorporation of research-driven CLT standards into building codes. “If you're going to just do a two-story residential home, you have a perfect design code pathway to do it,” said Shiling Pei of the Colorado School of Mines, chief investigator on a National Science Foundation (NSF)-supported study of seismic design methods. “But if you want to go taller, especially [if] you want to go above 85 feet— that is currently IBC [International Building Code] for Type IV, heavy timber—then you have to do something else...a lot of testing to try to convince the local building-code officials.” He views CLT beyond about 20 stories skeptically, on economic grounds: “In my projects, I say it's tall wood; it's not high-rise wood.” Pei cites the 2011 CLT Handbook by Canadian nonprofit FPInnovations as a pivotal document, republished in a 2013 U.S. edition with input from the American Wood Council (AWC), Forest Products Laboratory, WoodWorks, and APA: The Engineered Wood Association (formerly the American Plywood Association). In 2011, APA and the American National Standards Institute developed a performance-based standard, PRG 320, updating it in 2012 and 2017; it offers detailed specifications on CLT products' composition, dimensions, shear strength, stiffness, and other properties. The AWC's National Design Specifications for Wood Construction and the IBC include basic CLT sections in their 2015 editions. Since seismic risks in Europe (Italy excepted) are milder, the transfer of CLT technology to Canada and the U.S., particularly for larger scales and open plans, requires standards addressing lateral forces. The next hurdle is for the American Society of Civil Engineers' influential code book, ASCE 7: Minimum Design Loads for Buildings and Other Structures to address CLT, particularly its response-modification coefficient or R factor (not to be confused with R values for thermal resistance) in its seismic design provisions. “To make [CLT] economically competitive,” van de Lindt said, “it really needs to have these seismic performance coefficients (essentially an R factor) in the code, so that people don't have to get special permission every time they want to use it,” incurring engineers' reviewing costs. Results of van de Lindt's R-factor studies are expected next year, and the code-revision cycle takes about five years; if a proposal based on the findings passes review by Building Seismic Safety Council committees and a public-comment period, it should enter the 2022 edition of ASCE 7, then IBC. “With CLT, everything rotates like a rigid body under seismic stresses," van de Lindt said. "Panels do not deform enough to dissipate energy and suck load right into them.... For a steel special moment frame that's detailed for seismic, it can be an R of 8, [which has] a lot of ductility.” Yet adding concrete or steel lateral systems, as in Brock Commons (Acton Ostry Architects, Vancouver, page 12) and Carbon12 (PATH Architecture, Portland), respectively, requires multiple trades on-site and squanders CLT's construction speed. Advanced “disruptive technologies” common in Japan (base or inter-story isolation using sliders, rockers, or damping devices) require special review. Very tall wood, 20 stories and above, he believes, calls for performance-based modeling rather than prescriptive tables and “will always require review, at least in our lifetime.” Andre Barbosa of Oregon State University's School of Civil and Construction Engineering and Tallwood Design Institute concurred, noting that CLT projects above about ten stories are often hybrids with concrete cores or steel for lateral resistance. “You get the best out of both materials. You have the CLT that's lighter; [its] strength-to-weight ratio is very, very good. You get the concrete that allows you to go to longer spans, but also it creates that natural barrier for smoke and essentially for fire across floors.” Current methods of addressing timber's susceptibility to moisture and insects are generally adequate, he says, adding that long-term deflection (creep) in CLT buildings tall enough for large loads needs further study. Supported by the NSF's Natural Hazards Engineering Research Infrastructure Tall Wood program, Pei and colleagues recently built a two-story prototype for testing on the world's largest shake table at the University of California San Diego. Simulating 14 quakes of varying severity up through a "maximum credible earthquake," a once in 2,500-years event, “the building essentially received no damage, and we don't need to repair anything,” Pei reported, noting that CLT rocking walls actually outperformed their concrete and steel counterparts in resilience. His next studies will test a ten-story building under combined seismic stress and fire; the experiment has earned the inevitable nickname “shake and bake.” Flammability is “a concern very often expressed, but an easy one to dismiss,” said Lech Muszynski, associate professor of wood science and engineering at Oregon State University's College of Forestry. Studies support the counterintuitive idea that charring produces an insulating layer that actually slows pyrolysis, making it advance predictably and sparing enough wood to pass two-hour fire-resistance tests. “I've done some testing on unprotected CLT assemblies here in the states, large-scale floor and wall assemblies; there is a large library of similar tests being done in Europe in the past,” Muszynski reported, crediting Ario Ceccotti of the Istituto per la Valorizzazione del Legno e delle Specie Arboree (Trees and Timber Institute) for similar research in Italy and Japan. These tests have largely involved exposed CLT, though in practice the material is commonly encapsulated in gypsum board, adding another hour or so to its fire-resistance rating. Two commercial CLT manufacturers in the U.S., Muszynski noted, Oregon's D.R. Johnson (which he advises) and Montana's SmartLam, have their products fire-certified. Steel components within joints, Muszynski added, are more vulnerable than the wood. He uses a photo from the 1906 San Francisco fire to illustrate “the difference between flammable and fire-safe”: A severely burnt wooden beam shows charring and exposed nails, indicating deep fire penetration, but remains rigid, while two heat-weakened steel beams flop across the wooden member, resembling soggy pasta. Adhesives also require attention: Some bonded timber products use melamine urea-formaldehyde resins, which harden under heat, but the more common adhesive is polyurethane, which softens if the char reaches bond lines. Moisture can be more hazardous when worksite protections are lacking: Muszynski recalls an Italian project where financial delays left a site idle for several months, exposing CLT to rain—and underscoring the importance of using contractors familiar with the material.
Placeholder Alt Text

How mass timber could transform our cities (really)

This is a preview of our special November timber issue. Mass timber is having its Maison Dom-Ino moment. At the 2014 Venice Architecture Biennale, a curious structure sat on the grass near the international pavilion in the Giardini. It was an engineered timber version of Le Corbusier’s Maison Dom-Ino, the seminal, prototypical reinforced concrete project, which was celebrating its 100th birthday. As a manifesto of sorts for modernism, the original Maison Dom-
Ino sent shockwaves through the 
architecture world and the built environment at large. It was a replicable, scalable building system made from simple columns and floor slabs, which could be stacked vertically and horizontally like dominoes. The 2014 version was commissioned by Brett Steele, then dean at the Architectural Association School of Architecture in London. He described the “afterlife” of the 1914 Dom-Ino as “a set of guiding, abstract, and idealized principles” that have shaped the world as we know it today. The choice of timber in this case is an interesting one, as mass timber seems to be today’s material that looks promising for the future, much like steel and concrete did in the 20th century. As outlined in this issue, timber has a litany of benefits including carbon sequestration, lower embodied energy than steel and concrete, psychological benefits for inhabitants, less construction noise in tight urban sites, easier on-site construction in general, and many other positive aspects. It would reorient wood from light-frame suburban development toward mid-rise dense urban development. Taller and taller timber towers serve as the “Eiffel Tower” moments for the rapidly expanding timber industry, as pointed out by Jimmy Stamp in the Smithsonian Magazine article, "Is Timber the Future of Urban Construction?" And these important projects have brought attention to an otherwise niche building trade. Alongside these "Wow!" projects, there is another, less sexy side of the timber revolution that could help to change the way we build in America. New technologies abroad are already making mid-rise construction cheaper and more viable at larger scales. This incremental progress is taking place among manufacturers, architects, engineers, and designers as we speak in places like the nearly 600,000-square-foot Arbora complex in Montreal, Quebec. And companies, such as Nordic Engineered Wood, are expanding in the U.S. market, a place known for innovation that makes things cheaper and more market-ready. Once the market can produce mass timber structures more cheaply than steel and concrete, there could be a seismic shift. And as timber becomes more viable for safety concerns, and more legal through local codes adapting ("The State of the Art of Timber"), we could see timber proliferate at the same rate as the early-20th century saw the Maison Dom-Ino’s system spread across the world over the next 100 years. But of course we are speculating a bit in this issue. The future is not so clear. A fight is brewing in Congress ("What Wood You Do?") over the bipartisan Timber Innovation Act (and along with it, lobbying antics from the steel, concrete, and sand industries). If U.S. governmental agencies and private companies—namely manufacturers—come together, the costs could come down. It is possible that architectural knowledge-research and development could bend the markets so as to impact both economic and environmental resource allocation networks toward a lower-carbon future, as architect and timber expert Alan Organschi told AN in a conversation. The arms race is already on, and the National Forest Service has awarded $250,000 to Boston-based IKD to develop a hardwood-based cross-laminated timber (CLT), which is an important incremental step in the process. This issue speculates on a future where entire blocks might be built with green technologies including mass timber, and whole cities could be filled with beautiful wood buildings layered onto the stone, brick, steel, glass, and concrete urban fabric. How this revolution might play out is unclear, but we are seeing glimpses of what might be to come, such as Framework by LEVER Architecture in Portland, which will be the tallest timber building in the U.S., or the work of Michael Green Architecture in Vancouver, or Gray Organschi Architecture out of New Haven, Connecticut, which has been researching mass timber at the Yale School of Architecture. We also look to Europe and Canada for success stories that might be examples for the future of mass timber in the U.S. As Steele said of his 2014 Maison Dom-Ino, “This initial installation will remind visitors not only of modern architecture's most foundational project, but of an architectural instinct made even more apparent today than it was at the time of its original conception; namely that architecture always operates in the space created by a contrast between architecture as already known, and what it might yet become.” Can we imagine a partially wooden future? This article will be updated with links to other articles from the November timber issue.
Placeholder Alt Text

New federal act could give mass timber a big boost

Climate-change denial appears to be on the verge of becoming official U.S. policy. But all hope for reducing our carbon footprint is not lost. Case in point is the pending Timber Innovation Act, one of the rare eco-friendly pieces of legislation that enjoys bipartisan support. The bill (H.R. 1380, S. 538) seeks to establish a market for so-called mass timber buildings more than 85 feet tall that are built from panelized wood construction products such as cross-laminated timber (CLT) and glued-laminated timber (glulam).

“Building with wood benefits both rural economies and the environment,” U.S. Senator Debbie Stabenow (D-Michigan) said when she announced the legislation in early March. “This bill will help expand markets for wood products coming out of forests in Michigan and all across the country. At the same time, using wood for construction reduces pollution and incentivizes private landowners to keep their land forested, rather than selling it to developers.”

Architects who study the new wood construction materials say mass timber has economic, ecological, seismic, and aesthetic advantages over steel and concrete. “Photosynthesis, the process of growing a tree, absorbs C02,” explained New Haven architect Alan Organschi, adding, “Until it burns or decomposes, that carbon will stay in the wood like a bank investment.”

The concrete and steel industries are adamantly opposed to the Timber Innovation Act. More than 160 stakeholders from the construction, labor, and building materials sectors jointly signed a letter to the U.S. Senate opposing a version of the bill introduced last year. The letter questioned the fire and structural safety of mass timber and stated the bill would create an “imbalance in the marketplace by allowing the federal government to choose winners and losers.”

However, the bill’s supporters say the new wood technology promises to significantly reduce carbon loads in the building industry, which is currently responsible for close to half of the U.S.’s greenhouse gas emissions. A typical mid-rise concrete and steel building, because it relies on pollution-generating resource-extraction industries, is responsible for emitting 3,210 tons of CO2 in its construction and lifetime, according to Timber City, an initiative undertaken by Organschi’s firm, Gray Organschi Architecture, that is supported by the Hines Research Fund for Advanced Sustainability at Yale University. In contrast, because trees are a renewable resource that sequesters CO2, a typical mass timber mid-rise building built from wood harvested from sustainably managed forest is responsible for capturing 4,720 tons of CO2.

Innovations in mass timber technology also resolve fireproofing and seismic issues that, until recently, were a major disincentive to using wood in large urban buildings, according to Yugon Kim, founding partner of the architecture firm IKD, who curated the exhibit Timber City at the National Building Museum in Washington last fall. “U.S. cities in the 1800s used to be made of wood, but then because of urban fires that started to change,” he said. “Now, because of products like CLT, we will be able to use wood in the centers of our cities the way we did in the past.”

Tall wood building construction is most advanced in Europe, especially in Austria, which boasts the world’s largest mass timber industry. An example of a commercially viable mass timber development that garnered worldwide attention is the nine-story Murray Grove designed by Waugh Thistleton Architects, which was built in London in 2009. It consists of wood load-bearing walls, wood elevator cores, and wood floor slabs. In addition to paying off for the environment, Murray Grove took only 49 weeks to build, whereas an equivalent-size concrete structure would typically have taken 72 weeks to build.

The mass timber industry is still in its infancy in the U.S. There are only several wood companies that make mass timber products, and local building codes generally disallow tall wood structures. The Timber Innovation Act seeks to change that situation by funding competitive research on mass timber technology at institutions of higher learning and by making funds available for a tall wood building competition and a wood innovation program for retrofitting sawmills in areas where there is high unemployment.

The pending legislation expands upon a federal program that established an earlier U.S. Tall Wood Building Prize Competition, which in 2015 awarded $3 million to support the construction of two such structures. One was Framework, a 12-story mixed-use building in Portland, Oregon, designed by LEVER Architecture, which is due to break ground this summer. The other was 475 West 18th Street, designed by SHoP Architects, an upscale residential building project near the High Line that was shelved in early March, reportedly in response to a market downturn for high-end properties.

Getting government sponsored research funding was critical to defraying added expenses associated with the extensive testing and research necessary to secure local building department approvals for building wood structures more than six stories, according to Thomas Robinson, founding principal of LEVER Architecture. “Whenever you are doing something for the first time it is more complicated,” he said, noting that a critical aspect of his project was demonstrating that exposed CLT and glulam can achieve a two-hour fire-resistant rating.

Given the increasing environmental concerns over the widespread use of steel and concrete, mass timber promises to be a more palatable alternative. “What the Timber Innovation Act does is make this an even playing field,” Organschi said. “We have these vast forest reserves which are not being utilized.… By using mass configurations of timber, we will get more carbon sequestration.”

Placeholder Alt Text

UMass Amherst completes cross-laminated timber Design Building for architecture, other programs

Boston-based Leers Weinzapfel Associates recently completed construction of the new Design Building at the University of Massachusetts Amherst, the first academic building in the U.S. to use a Cross Laminated Timber (CLT) as its primary structure. (See images of the building under construction here.) Targeted for LEED Gold, the building includes other sustainable architectural features like bio-swales for water runoff filtration, a green-roof which doubles as an outdoor classroom, and the largest installation of wood concrete composites in North America. The building is described by Principal Architect Andrea Leers as “a teaching tool for the design disciplines.” Leers made the case that educational environments, especially those for design school, can serve a pedagogical function in the training of young architects. Leer stated further that:
From my own teaching experience there’s nothing more potent than being able to talk with students about the space around you—in this case, the building’s collaborative configuration, innovative structure, considered material and detailing choices, environmentally-driven site, and synergistic landscape concepts that define the project.
The building is organized around an interior atrium lit during the day by several skylights. This daylighting strategy reduces energy consumption and provides the school with a bright central space for exhibitions, design critiques, lectures, informal gatherings, and other events. The studios and classrooms are arranged around the atrium, visually connected to the commons through window apertures that allow visitors to glimpse the work being done by the students and faculty. The design of the building’s commons also emphasizes the unification of the university’s departments of Architecture, Landscape Architecture and Regional Planning, and the Building and Construction Technology program into one singular facility. In addition to its extensive use of wood products, the architects chose to clad the building with copper-finished aluminum panels that protect the highly-efficient envelope. Though the building fills much of the site, the landscape design by Stephen Stimpson Associates strategically uses native plants and local paving materials to connect the building to the larger campus. In the end, the building cost $52 million to construct, a price tag that was partially funded by Massachusetts State Legislature, and adds 87,500-square-feet of additional interior space to the university. Suffolk was the construction manager.
Placeholder Alt Text

LEVER Architecture is bringing mass timber construction into the mainstream

The Architectural League’s Emerging Voices award and lecture series spotlight individuals and firms with distinct design “voices” that have the potential to influence the discipline of architecture, landscape architecture, and urban design. The jury, composed of Sunil Bald, Mario Gooden, Lisa Gray, Paul Lewis, Jing Liu, Thomas Phifer, Bradley Samuels, Billie Tsien, and Ian Volner, selected architects and designers who have significant bodies of realized work that creatively address larger issues in the built environment.

The Architect’s Newspaper featured the Emerging Voices firms in our February issue; stay tuned as we upload those articles to our website over the coming weeks. The firm featured below (Portland, Oregon–based LEVER Architecturewill deliver its lecture on March 16, 2017, at The Architecture League in New York City. Click here to learn more!

Architect Thomas Robinson kick-started his career with Joseph Esherick, the architect best known for designing the Hedgerow Houses at Sea Ranch, California, followed by stints leading institutional and cultural projects at Herzog & de Meuron in Switzerland and Allied Works in Oregon. In 2009, Robinson, a graduate of UC Berkeley and later Harvard (studying under Peter Zumthor), decided to branch out on his own, launching LEVER Architecture from his Portland basement.

Over the past eight years, his firm has grown to 18 employees. A winner of the USDA’s U.S. Tall Wood Building Prize, LEVER Architecture has found a niche working with cross-laminated timber (CLT). “Timber is often hidden away,” Robinson said. “We want [timber] to be part of a greater architectural experience.” While mass timber construction isn’t new—according to Robinson it has been around since the 1930s—there is a rediscovering and understanding of the technology coupled with modern advances in fire safety, seismic engineering, and acoustics that has made it more feasible.

LEVER Architecture is currently working on a 90,000-square-foot, 12-story CLT high-rise in Portland. The project, Framework, incorporates a wood-core structure. When completed in 2018, it is expected to be the first mass-timber high-rise in the United States. The design relies on a post-tension CLT rocking wall, which, as Robinson explained, is a resilient low-damage design that takes advantage of the lightness and strength of wood. “Wood moves and can re-center itself,” he said.

Other recent LEVER projects also feature mass timber: There is Albina Yard, the first office building in the U.S. built with domestically manufactured CLT (LEVER Architecture recently moved its offices to this four-story, 16,000-square-foot building), and L’Angolo Estate, a winery tasting room in Newberg, Oregon.

At the core, Robinson explained that LEVER’s design projects are about the transformative power of materials. “It’s almost akin to product design at the level of a building.”

With funding from the National Science Foundation and a $1.8 million grant through the U.S. Tall WoodBuilding Prize, LEVER is implementing a performance-based design process throughout its projects. The grants help pay for additional research costs to demonstrate that CLT high-rise buildings are equivalent to traditional steel construction.

LEVER advocates mass timber as a more sustainable way of building while encouraging economic growth in the Pacific Northwest. “We look to the farm-to-table model, where people are connected more directly to the producer,” Robinson said. Translated from the culinary scene to the architecture world, the “forest-to-frame” approach is about building stronger relationships between architects, contractors, and the people growing the timber.

“We focus on simple materials and how to put them together to form transformative experiences,” Robinson said. “We’re interested in an economy of means. It’s rare being both at the cutting edge and having a seat at the table.”