Thanks to a recent addendum to Oregon’s building code, the state is the first in the country to allow timber buildings to rise higher than six stories without special consideration. Portland has become something of a hotbed for timber innovation as of late. Carbon12, PATH Architecture’s eight-story glulam and cross-laminated timber (CLT) tower with a steel core, recently became the country’s tallest timber building and was set to be surpassed by LEVER Architecture’s 12-story Framework. Alas, that project was put on hold due to mounting financial difficulties last month, but it seems the precedent that the project achieved in securing a building permit from the State of Oregon and City of Portland will live on. The timber allowance comes courtesy of Oregon’s statewide alternate method (SAM), a state-specific program that allows for alternate building techniques to be used after an advisory council has approved the “technical and scientific facts of the proposed alternate method.” The allowance comes after the International Code Council (ICC)–the nonprofit group that Oregon models its building codes after–established the ICC Ad Hoc Committee on Tall Wood Buildings in 2015 to explore the benefits and challenges of using timber in tall buildings. A Committee Action Hearing was held in April of this year, where the Ad Hoc Committee, made up of code experts, stakeholders, and industry members presented their findings. All 14 of the committee’s suggestions were adopted, introducing standards and best practices for fireproofing, the load-bearing potential of CLT and heavy timber, water resistance, sealing, seismic ratings, and more. Three new building classifications were introduced as a result: Type IV A, timber buildings permitted up to 18 stories and 270 feet tall, Type IV B, timber buildings with a maximum height of 12 stories and 180 feet, and Type IV C, which is permitted to rise nine stories and 85 feet tall at maximum. The shortest of the timber typologies is allowed to use exposed structural timber as an interior finish, whereas the tallest, type A, must enclose all exposed surfaces and include a three-hour fire-resistance rating for the structural elements. “We congratulate the State of Oregon on becoming the first state to provide building code recognition for construction of tall, mass timber buildings,” said American Wood Council President & CEO Robert Glowinski in a statement. “Mass timber is a new category of wood products that will revolutionize how America builds and we’ve seen interest in it continue to grow over the last several years. This action by the Codes Division Administrator helps code officials in Oregon by making provisions consistent throughout the state. In adopting this new method, Oregon has also recognized the significant environmental benefits that accrue from greater wood product use.”
Posts tagged with "Timber":
Interested parties have been left standing around for an extra week while they wait to find out the three finalists of Portland, Oregon's Street Seats: Urban Benches for Vibrant Cities design competition. The announcement ceremony was rescheduled to avoid a potentially violent political protest at the adjacent Tom McCall Waterfront Park and eventually took place on August 9 in downtown Portland. Street Seats was an international competition to design new public benches for the city of Portland. Design Museum Portland organized the competition in partnership with Portland General Electric Company (PGE) and World Trade Center Portland (WTCP), which is also the site where the 15 semi-finalists have been installed. Nestled between the Willamette River and downtown, the contest aims higher than merely bolstering public seating. Juror Kregg Arntson, executive director of the PGE Foundation, hopes the seats "inspire people to come down and enjoy the community." Launched in January, the competition attracted over 200 international entrants, and many referenced the Pacific Northwest's rainy climate and penchant for locally sourced wood construction. In addition to basic physical and safety requirements, the design brief emphasized sustainable materials and innovative processes while requiring a 1/8th scale model and a video. Fifteen shortlisted entrants received $1,000 grants to fabricate and install their prototypes on site. Portland-based Kyle and Alyssa Trulen, a landscape architect and a videographer respectively, took the grand prize with their entry A Quiet Place to Sit and Rest. Inspired by author Shel Silverstein's "The Giving Tree," the bench reflects the design of a stump and protects the trees it's installed around from soil compaction and bark damage. The thermally treated pine and ash are also insect resistant. "The real purpose of the seat design is not merely protection," said the Trulens, "it's about the relationship of a person with a tree...in hope of a healthier urban environment for both." The runner-up, Fluid Wood, was the result of a collaboration between Portland-based architect Norberto Gliozzi and Axiom Custom Products. Fluid Wood comprises layers of laminated wood cut in an egg-like form. Another finalist by The Tubsters, from Berkeley, California claimed the people's choice award for Tub(Time), a cut-away bathtub containing hardened transparent resin representing the Willamette River and a topographical map of the downtown and central eastside. Passersby are encouraged to climb in and recline. The Design Museum, which hosted a similar Street Seats competition in Boston in 2013, was not the first to sponsor such a challenge in Portland. The City of Portland Bureau of Transportation (PBOT) had developed guidelines in 2012 based on similar programs in New York and San Francisco to convert on-street parking spaces to public use. During a 2014 collaboration with the Center for Architecture, Portland yielded two winning submissions for seating that were installed in the city's northeast quadrant. In the summer of 2015, Portland State University architecture students designed and built a seating structure downtown. PBOT canceled the 2016 competition for an uncharacteristically low response rate; however, PBOT's program still exists outside of the downtown area. This year's Design Museum Portland competition is unrelated to the City's previous efforts and was launched independently. Many passersby spontaneously stopped to try the seats and participate in the announcement ceremony after the unveiling, reaffirming Design Museum Portland's managing director Erica Rife's statement that it is "important to be a good neighbor and inspire this community to be closer"—a much-welcomed change from the previous weekend's police and protester standoff. The 15 seats and over 200 1/8th scale models will remain on view until February. Several seats—Fractal Rock by Holst Architects, B_tween Bench by Gamma Architects, and Fern by Yingjie Liang, in addition to the winner and runners-up—will remain installed at the WTCP while the others will be relocated to sites throughout Portland. An online exhibition and schedule of accompanying programs are hosted at designmuseumportland.org.
A research team led by Jamin Dillenburger, an assistant professor at ETH Zurich, has recently produced and installed a concrete ceiling shaped by 3D-printed sand formwork. Dubbed the “Smart Slab,” the 1000 square-foot ceiling is significantly lighter and thinner than comparable concrete ceilings. The concrete slab is a component of ETH Zurich’s ongoing DFAB House project. The DFAB House is a load-bearing timber module prefabricated by robots. According to ETH Zurich, Dillenburger’s research group “developed a new software to fabricate the formwork elements, which is able to record and coordinate all parameters relevant to production.” In effect, the design of the ceiling is the product of the team-created software rather than analog design or planning. Following the design and digital testing phase of structural elements, the fabrication data was exported for the creation of 11 pallet-sized, 3D-printed sand formworks. After fabrication, each segment was cleared of sand particles and prepared for concrete spraying. The spray consisted of several layers of glass-fiber reinforced concrete. At its thinnest point, the concrete shell is less than one inch thick. After hardening for two weeks, the 11 concrete segments were joined to create the approximately 15-ton floor plate. While the underbelly’s contours were formed by 3D-printed sand casts, the ribbed grid above was shaped by CNC laser-cut timber formwork. The load-bearing ribs, resulting from timber formwork, were outfitted with a series of tubes for the insertion of steel cables both horizontally and vertically. These post-tensioned ribs carry the principal load of the “Smart Slab.” In placing the principal load above the concrete shell, the research team was able to insert complex geometric features below. The “Smart Slab” is not ETH Zurich’s first execution of an ultrathin concrete unit. Earlier this year, the university fabricated an undulating, two-inch thick roofing unit for a new live-work space in Zurich.
Last November, the U.S. Department of Commerce under President Trump announced an average of 21 percent import duties on Canadian timber products entering the U.S. The announcement was greeted with mixed reactions within the construction industry; builders claimed that the tariffs would increase the cost of construction, and American suppliers argued that the domestic timber industry would benefit, expand, and keep wood prices low. Single-family home construction in the U.S. relies heavily on Canadian softwood for roofing and framing. In 2017, Canadian lumber yards supplied 28 percent of the U.S. softwood lumber market, and home builders have been the first to raise concerns about the new duties, which were in effect by January. The National Association of Home Builders (NAHB) claims that the imposed tariffs have added approximately $9,000 to the cost of single-family homes and up to $3,000 on multi-family homes. The NAHB doesn’t believe U.S. domestic production is capable of meeting the current market demand and that the tariffs only hurt native manufactures by forcing them to increase their lumber prices. The NAHB is calling for the Trump administration to resume talks with Canada to secure a more mutually beneficial long-term agreement. David Logan, director of tax and trade policy analysis at the NAHB, says that historically, the U.S. lumber field has never been able to support rapid housing growth. “Buyers are still buying from the distributors they’ve always sourced from despite the tariffs,” he said. “Domestic lumber production has increased marginally in the last year, but it’s not kept up with the housing demand in terms of percentages, so it’s hard to say that we’re meeting the challenge. This has always been the case. We can’t meet that need...not even close.” Logan also argued that larger lumber companies in the U.S. are profiting unfairly from the deal, citing the Seattle-based Weyerhaeuser, which owns 12.4 million acres of forest in the U.S. alone and manages 14 million acres in Canada, as well as West Fraser, a Vancouver-based company that operates 48 mills across both countries. The NAHB claims that these companies are able to reap the benefits of both markets under the current trade agreement and likely won’t be affected if things change again. “We say over and over again that we need predictable and stable supply. That means using Canadian lumber,” Logan said. “Diversification of operations in the biggest mills on both sides of the border has really hampered any progress towards talking further about this issue because they’re able to increase production and do well. Prices have been so high there’s not really room for anyone but the big players to have a seat at the table, whether they’re Canadian or American.” The U.S. Lumber Coalition (USLC) rejects these claims. “Since the duties were implemented," the USLC wrote in a statement last week, "U.S. lumber shipments have increased by about 1.4 billion board feet, roughly filling the gap left by the decrease of Canadian imports. U.S. companies continue to invest in expanding their production capabilities to mill lumber from American trees by American workers to build American homes.” Pleasant River Lumber, a small milling company based in Maine, isn’t experiencing the negative side effects that the NAHB claims is coming out of the current tariffs on timber. In fact, the company is on track to complete a $20 million expansion at two of its four sawmills in the next 18 months. As part of the USLC, Pleasant River Lumber sources 95 percent of its lumber within the state of Maine and takes a bit from New Hampshire and Canada as well. Owner Jason Brochu is pleased with the country’s newfound focus on local production and plans to take advantage of it. “Increased demand due to forest fires and hurricanes in other states, spiked prices from the duties, heightened transportation costs, and a strong housing market all factor in to establish a level playing field for lumber production in the U.S. right now,” said Brochu. “We can’t compete against the government or any larger mills without things being equal.” Pleasant River Lumber is capitalizing on the growing lumber market by adding 50 percent more capacity to its production facilities and hiring 40 new employees as quickly as possible. They plan to boost production of their dimensional lumber from 200 million to 300 million board feet annually with the upgraded equipment. More importantly, they’re investing in their framing mills to address the increased demand within the housing market. “We believe we’re pretty typical of most mills in the country at this time,” Brochu said. “Most mills in Maine specifically are adding shifts or putting more money into mills to increase volume. We’re confident that the duties protect our rights as producers in the U.S. and we feel like the laws are working the way they should.” Brochu also emphasized how “relatively insignificant” framing lumber is in housing construction. USLC said the same thing stating that lumber makes up only 2 percent of the cost of a new home—which in 2018 stands at $368,500. Framing lumber isn’t the only wood material that’s used to construct new homes. Plywood, which has zero duties imposed on it, flooring, and other timber products are also increasing in price. New York-based specialty wood-product manufacturer Hudson Company said the niche wood market has been affected as well. Two of its most popular reclaimed-wood products, both of which feature Canadian imported lumber, have both been impacted dramatically, says owner Jamie Hammel. Sales of silver pine siding are down by 60 percent, while hand-hewn beams are down 40 percent. “The reason our business is not down by 60 percent,” he said, “is because we sell other things. But we've had to limit the amount of volume we import because of the tariffs and we’ve had to diversify our product line to adjust and will continue to do. We’ve had to source more products locally which I guess was the administration’s goal.” The timber tariffs against Canada were among the first official duties placed on another country by the U.S. government since Trump took office. In the ten years since the Softwood Lumber Agreement (SLA) was established in 2006, the U.S. Commerce Department has allowed Canadian companies to sell lumber to the U.S. market at subsidized prices, lifting previously countervailing and anti-dumping duties as long as prices stayed above a certain figure. The SLA expired in 2015 and since then both countries have been unable to negotiate a new deal. On behalf of the NAHB, Logan said that his organization doesn't foresee a new Canada-U.S. deal happening in the near future. “We don’t think the dialogue will reopen any time soon as long as the North American Free Trade Agreement negotiations are ongoing. If history repeats itself...the last time this happened it took around 5 years to settle,” he said referring to the original SLA. “Hopefully I’m wrong and this is done very quickly. Until then, prices will maybe get a bit higher, but volatility will certainly increase.”
Yale University and Gray Organschi Architecture have designed and built a self-sufficient tiny house for UN Environment and UN Habitat, and the building is on display in UN Plaza in Midtown Manhattan until August 11. The Ecological Living Module contains 215 square feet of occupiable interior space and carves out another 16 square feet for a rear mechanical closet. The unit uses passive lighting and moisture collection, structural cross-laminated timber (CLT), food-growing green walls, and sun-tracking solar panels to shrink both the building’s embodied energy and resource needs. According to UN Environment, housing construction worldwide uses 40 percent of all resources produced every year and accounts for one-third of greenhouse gas emissions (not to mention the conflicts being fought over rapidly dwindling materials like sand). The module was commissioned just in time for the United Nations High-level Political Forum on Sustainable Development, to illustrate the idea that sustainable urbanization can only be accomplished if buildings minimize their contribution to climate change. The Yale Center for Ecosystems in Architecture and Gray Organschi worked together to design and install the module in only four weeks. The building was fabricated partially in New Haven and partially in Brooklyn and assembled on the UN campus amidst heavy security and tight construction restrictions. In order to balance maximum sun exposure with thermal comfort, the module was designed with New York’s specific micro-climate in mind. The dramatically-sloped building is clad in dark cedar planks and is home to two cascading “farm walls”, one on either side, and Gray Organschi claims that in New York the home can produce over 260 servings of vegetables. Plants were used inside as well in the loft area, and a living wall in the upper loft area purifies air for the inhabitants. “Structure was used as finish,” explains Gray Organschi founding principle Alan Organschi. The same pale CLT used to support the building was left exposed inside to create all of the finished surfaces, from countertops to stairs. The timber was sourced from the northeastern U.S. and sequestered more carbon than the effort used to harvest it. The team optimized daylighting in the building by carving strategic cuts into the back and roof. An Integrated Concentrating Solar Facade was installed to both reduce the amount of incoming sunlight and harvest solar power; an array of tiny panels track the sun’s movement and focus light on the minimally-sized solar receivers. The team wanted to build a system that could be assembled with the least amount of effort, and that would use the minimal amount of toxic materials to create. After August 11, the Ecological Living Module will be partially disassembled and brought to San Francisco; the structure was built narrow enough to be towed by truck. After that, the module will be flown out for demonstration in Quito, Ecuador, and then Nairobi, Kenya.
Timber construction continues its march to mass market feasibility following a series of live blast tests on full-scale cross-laminated timber (CLT) structures. Through a series of tests conducted at the Tyndall Air Force Base in Florida, the WoodWorks Wood Products Council and U.S. Army are putting together guidelines for framing buildings with CLT. As Engineering News–Record reports, the idea to test CLT for its blast resistance properties arose after developer and construction company Lendlease entered into an agreement to build hotels on army bases across the U.S. As Lendlease chose to frame some of their hotels with CLT to save on time and construction costs, they were told that CLT wasn’t explicitly mentioned in the Unified Facilities Criteria, the building code for the U.S. Army. This meant that the material would have to pass a battery of durability and security hardening-related tests before it could be applied in any real-world structures. While the Army allowed the construction of Lendlease’s first CTL hotel, the Redstone Arsenal in Alabama, any future timber-framed buildings would require full-scale testing on a physical mockup before it could be approved. Lendlease reached out to WoodWorks Wood Products Council, who arranged the seven blast tests, Karagozian & Case Inc. (KCI), who developed and followed through on both phases of the testing, the Air Force Civil Engineer Center, and the University of Maine. The tests were carried out in two phases–the first in late 2016, and second at the end of last year. Lendlease built the testing structures, each of which were exposed to successively larger blasts over a period of seven tests; two of the mock buildings were 27 feet tall with two-foot-tall parapets and window cutouts at 12 feet, and the third was 23 feet tall, with two-foot-tall parapets and window cutouts at 10 feet. Both “buildings” had 15-square-foot footprints. After exposing the structures to 32 pounds, 67 pounds, and 199 pounds of TNT (with 610 pounds used for the last test), KCI concluded that for blast exposure, CLT was equivalent to the standard steel-studded wall. Because CLT panels contain multiple laminated layers, the remaining wood provides additional strength at the point of rupture. The load from the blast is also more evenly distributed owing to the panel’s support on all four sides, allowing the force to be evenly distributed towards the joints. The U.S. Army Protective Design Center (PDC) has already released their report on the 2016 tests and will follow it up with their analysis of the second round of testing this June.
Is wood dangerous? It’s one of the oldest, most sustainable building materials (if harvested correctly) and recent advances in cross-laminated timber (CLT) have made it possible to build taller, multifamily timber buildings, but local building codes are just beginning to catch up. Sure, any Girl Scout knows that you can’t start a fire without it, but it’s generally considered kosher: CLT boosters say that if contractors know how to work with the material, timber is just as safe as steel. Despite their widespread use, concrete industry groups strenuously object to the use of “combustible materials” in construction. One industry group has launched an email campaign to ostensibly make members of the AEC industry aware of (non–fire-treated) wood’s shortcomings. These emails are part of an ongoing battle between the wood, concrete and steel industries, a conflict which seems to have escalated in concert with the growing popularity of CLT and the introduction of the timber innovation act, which would provide government support to the development of mass timber technology. With ominous subject lines like “Georgia Bill Would Leave Savannah Exposed to Hurricane Threat” and “Flames Quickly Consume Combustible Denver Apartment Complex Under Construction,” the emails seem to sow doubt about the durability and safety of timber buildings. The five-story, 84-unit Denver building detailed in the latter missive was under construction when it was engulfed by fire. “Combustible materials have no place in mid-rise housing projects, regardless of whether they’re under construction or fully operational,” said Kevin Lawlor, spokesperson for Build with Strength, which initiated the campaign, in the email. “These buildings are effectively tinderboxes on steroids, and when a fire breaks out, they’re incredibly difficult to extinguish.” Build with Strength is a partnership convened by the National Ready Mixed Concrete Association. As their names suggest, both groups are unabashedly pro-noncombustible materials, concrete and steel included. Reached by phone, Lawlor said Build with Strength doesn’t have a beef with wood—it just wants to fulfill its mission of educating the AEC industry on the benefits of ready-mixed concrete and its use in low- to mid-rise buildings. Its members include architects, engineers, steel and concrete interests, political leaders, and even religious organizations. “It’s not a materials fight,” Lawlor said. “The goal is to promote safer construction in three- to seven-story buildings. The notices are not specifically designed to go out and attack any particular industry.”
Sixty-three trees, 67 cross-laminated timber (CLT) panels, and 12 days—that’s what it took for Seattle-based atelierjones to erect the firm’s 1,500-square-foot CLTHouse, one of the first all-CLT residences constructed in the United States. The three-sided home is built on a leftover 2,500-square-foot triangular lot in Seattle’s Elliot Bay neighborhood on the shores of Lake Washington, where architect Susan Jones launched her research house experiment back in 2015. The house’s blackened, shou-sugi-ban treated exterior panels contrast with the blonde, white-washed, and daylit-spaces within the home, which emanate from a three-level circulation core containing a staircase, wet walls, and concealed utilities. The rustic home is inspired by the Northwest’s ubiquitous log cabins and features exposed wood paneling inside and out in homage to this building type. The approach, according to Jones, seeks to project a sense of “living with nature in the city” and provides a productive example of the smaller-scale capabilities of emerging CLT technologies. The house is punctured by triangular, gable-shaped windows that infuse it with daylight. Combined with the gypsum, plastic-laminate, stainless steel, and quartz-lined interior surfaces, it provides an “immersive, visceral, and natural experience,” according to the architect. Constructed using CNC-milled, rapidly renewable, and sustainably harvested CSFI-certified spruce, pine, and fir panels made by Structurlam, the building is crafted to inspire a sense of naturalistic escape and relaxation. The home’s exposed knotty pine aesthetic is reflected in a pair of stylized second-floor screened window walls that mark a triangular notch carved into the structure. Here, two pairs of sliding glass doors along the ground floor open the dual-lobed plan to the outdoors. Dining and living room spaces swing around this interior corner, where on one side, a thin plywood partition separates the dining and kitchen spaces from one another. Behind the kitchen sits a short hallway that connects the building’s backdoor entrance—located below a cantilevered bedroom suite—with the stair core. On the floor above, a trio of bedrooms, two bathrooms, and a reading nook cap off the home’s living areas while a rooftop deck overlooks the entire neighborhood from a wooden perch. The pilot house was developed as a research prototype and required extra municipal approvals to account for building codes that had not yet incorporated mass timber structural systems. Though crafted from sustainable materials from the start, atelierjones went one step further and planted 800 trees in conjunction with the project to act as an additional carbon sink. The result, according to Jones, is simply “hypernatural.”
Researchers at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, are giving timber construction a mechanical leg up with the introduction of prefabricated, robotically-assembled timber frame housing. Together with Erne AG Holzbau, a contracting firm that specializes in timber, researchers at the institute’s Chair of Architecture and Digital Fabrication have developed Spatial Timber Assemblies, a system for digitally fabricating and constructing complex forms from timber. After a model of the structure has been laid out, robotic arms mounted in the ceiling of the assembly chamber are capable of building the required parts as well as putting them together. First, one arm picks up a beam and holds it while a human trims the piece into the proper size and shape. Then, a second robot arm pre-drills the holes needed for attaching the beam to the structure; finally, both robot arms work together to precisely place the beam as a human attaches it. Thanks to algorithms developed by the researchers, the arms are able to constantly recalculate their location in space and how to move forward without bumping into each other (or humans on the job site). A major advantage of Spatial Timber Assemblies is that the structures built this way carry their load-bearing capacity structurally, and don’t require reinforcing plates or any additional steel. If the overall design changes during construction, researchers are able to calculate a new, optimized framing solution using load-distribution algorithms. The system is more than theoretical. ETH researchers are currently using it to assemble six unique modules, which will join to frame the top two floors of the experimental DFAB HOUSE in Dübendorf, a suburb of Zurich. Once installed on site, both floors will have distinct rooms across 328 square feet of floor space. The final design, which uses 487 individual beams, will be wrapped in a clear plastic facade so that the underlying timber structure can remain exposed. Advancements in robotic construction are advancing rapidly, and ETH researchers have been developing robots that weld, spray concrete, and stack bricks to create forms that would have been difficult to build previously. And if the ETH needs help decorating the interior of their research house, robots can now assemble IKEA furniture, too.
After tackling an underwater restaurant in the south of Norway late last year, Snøhetta has unveiled plans for a “floating” hotel in the country’s north. “Svart,” named after the adjacent Svartisen glacier, will produce more energy than it consumes thanks to the Arctic Circle’s 24 hours of sunlight during the summer months. Reminiscent of the space-aged Apple Park doughnut, the ring-shaped Svart will rise from the waters of the Holandsfjorden fjord via crisscrossed timber columns and would provide guests with panoramic views of the lake and surrounding Almlifjellet mountain range. A round, wooden boardwalk will be suspended between the support struts and guests can stroll above the lake in the summer months; the path will be used for canoe storage in the winter, negating the need for an additional boathouse. The circular construction references Norwegian vernacular architecture, and draws inspiration from both the “fiskehjell” (a wooden, A-shaped structure for drying fish) and the “rorbue” (a type of traditional seasonal house used by fishermen), as fishing poles informed the wooden support design. Wood panels will also be used to clad the hotel’s exterior. As part of preserving the fragile natural landscape around the hotel, Svart will generate all of its electricity on site. Meeting Powerhouse standards (a collaboration meant to stoke energy positive building construction) will be accomplished both through design as well as technology. The hotel’s circular edge is rimmed with private terraces, which will set the building’s façade back and shade against solar insolation in the summertime, while the floor-to-ceiling windows will let sunlight passively heat the interior in the winter. The roof will be clad in locally produced solar panels, made with clean hydroelectric power, and the building will be constructed from materials with a “low embodied energy,” such as wood, meaning that a minimum amount of energy went into producing them. In designing the shape of the building’s roof, Snøhetta optimized the panels’ orientation to best take advantage of the “midnight sun” effect, where the sun never sets during the summer months in the Arctic Circle. Geothermal wells connected to heat pumps will warm the building in the colder months. Altogether Snøhetta estimates that Svart will use up to 85 percent less energy than a hotel of comparable size. “Building an energy positive and low-impact hotel is an essential factor to create a sustainable tourist destination respecting the unique features of the plot; the rare plant species, the clean waters and the blue ice of the Svartisen glacier,” said Kjetil Trædal Thorsen, Founding Partner at Snøhetta, in a press release. Svart is being developed in collaboration with tourism company Arctic Adventure of Norway, consulting firm Asplan Viak, and Skanska. Together the four companies make up Powerhouse, a group dedicated to advancing the construction of “plus houses,” buildings that produce more energy than they consume over a 60-year period, including the usage of building and demolishing the structure. No estimated completion date has been given at the time of writing.
Thanks to a two-year, $250,000 Wood Innovations Grant from the United States Forest Service, and with further support from the National Hardwood Lumber Association, Indiana Hardwood Lumberman’s Association, and the Indiana Department of Natural Resources, IKD is currently working on an advancement that may completely change the cross-laminated timber (CLT) market. Currently, CLT is made primarily of softwoods, which have the advantage of being fast growing and inexpensive. IKD believes the future of CLT should also include hardwood, and now it just might. As a proof of concept, IKD has constructed a large installation, which stands as the first hardwood CLT structure in the United States. The project was built with an experimental CLT material made from low-value hardwood-sawn logs for Exhibit Columbus, the new architectural exhibition in the modernist mecca of Columbus, Indiana. A reference to the conversation pit in the Eero Saarinen–designed Miller House, the IKD’s Conversation Plinth is a multilevel occupiable installation in the plaza in front of the I.M. Pei–designed Cleo Rogers Memorial Library. The motivations behind using hardwood are two-fold. Currently, over 50 percent of the 80 million cubic feet of hardwood harvested in Indiana each year is used for low-value industrial products. By integrating this wood into the higher-value CLT, it raises the value of what is already Indiana’s largest cash crop. And from the perspective of designers and engineers, hardwood CLT provides the possibility of a more fire-resistant panel and a form-factor advantage. “We are currently exploring a number of applications that could have larger scale building applications,” IKD partner Yugon Kim said. “Since hardwood has superior mechanical properties, we believe we can achieve a panel that could be thinner to meet the same structural capacity of an equivalent softwood CLT panel.” The Conversation Plinth is not simply an exhibition piece for IKD. It is a test of the hardwood CLT the firm developed with SmartLam, the first CLT manufacturer in the United States. Over the months, the project will be subjected to the varied and sometimes-extreme weather of south-central Indiana, providing firsthand data that IKD and SmartLam can use to advance their research on the material. From the beating sun of late summer through the sleet, snow, and ice of winter, the project will be monitored for durability as well as aesthetic and structural changes. “We are closely observing the mixed-species panels and seeing how they react in the extreme temperature and moisture fluctuations so that we can continue to refine the species mix within the panel, the adhesion process, and the finish application and approach,” Kim explained. “It is really interesting to see how differently hardwood moves from softwood when the moisture content varies, and we are looking deeper at the fiber structures and unique characters of species themselves as well to create a superior CLT panel.” The project continues much of the timber research IKD has been doing, including its design for the Timber City at the National Building Museum in Washington, D.C., and work on timber modular waste units, a timber version of CMU made from timber waste that has won numerous awards. Resources Project Lead and Designer IKD CLT Fabrication SmartLam Timber Engineering Bensonwood Phase One Hardwood Testing Material Supplier Pike Lumber Company Phase Two Conversation Plinth Hardwood Material Supplier Koetter Woodworking General Contractor Taylor Brothers Construction Co. Softwood Material Supplier And Fabricator Sauter Timber
If the steady stream of newly announced mass wood projects is any indication, mass timber building technologies are poised to take the American construction and design industries by storm over the next few years. As products like cross-laminated timber (CLT), nail-laminated timber (NLT), glue-laminated timber (glulam), and dowel-laminated timber (DLT) begin to make their way into widespread use, designers, engineers, and builders alike are searching for the best—and sometimes, most extreme—applications for mass timber technologies. But rather than reinvent the wheel, American designers can look to experienced mass timber designers in Europe and Canada for key lessons as they begin to test the limits of these materials in the United States. European and Canadian architects and researchers have long been at the forefront of mass timber design, starting with early experiments in the 1970s. By the 1990s, researchers like Julius K. Natterer at the Federal Institute of Technology in Lausanne, Switzerland, were developing initial CLT prototypes. Natterer’s work has been buttressed by that of many others, including research performed at the Norwegian Institute of Wood Technology under Thomas Orskaug and experiments conducted at the Technical University of Munich under Stefan Winter. One key lesson European timber projects teach is that when it comes to structural systems, weight matters. On average, mass timber assemblies weigh between one-third and one-fifth as much as concrete structures, despite equivalent structural capacities. As a result, mass timber buildings are much lighter than concrete ones, a positive for building in tricky urban situations, for example—where underground rail yards, subway tunnels, and municipal utilities place limits on how heavy and tall buildings can be. London-based Waugh Thistleton Architects (WTA), for example, recently completed work on Dalston Lane, a 121-unit CLT midrise complex located above a tunnel serving the Eurostar train line in the city’s Hackney neighborhood. For the project, the architects worked with timber-engineering specialists Ramboll to develop a stepped tower cluster rising between five and ten stories tall. CLT panels are used for the external, party, and core walls of the building, as well as the stairs and the building’s floors. The variegated massing is due directly to the architect’s use of CLT construction, which resulted in a lighter building that allowed the designers to build taller without more extensive foundations. The resulting building, with its staggered massing, better maximizes daylight infiltration into apartment units. The added height allowed the architects to add 50 more units to the project than originally permitted, a testament to just how light CLT can be. Andrew Waugh of WTA said, “Timber buildings are just simpler, cheaper, and nicer [than concrete ones]. High-density urban housing should be built using mass timber.” Lighter mass timber buildings also perform better in seismic zones. Since the lighter buildings carry less inertia, the potential for catastrophic swaying goes down. The strategy was applied this year with the Brock Commons tower, an 18-story, 400-bed college dormitory designed by Vancouver-based Acton Ostry Architects for the University of British Columbia Point Grey campus. The tower is made up of a hybrid structural system that includes CLT floor slabs, glulam columns, steel connectors, and dual concrete cores. The concrete cores anchor the light mass wood structure in place, helping to counteract seismic and wind-generated forces. The 173-foot-tall structure is currently considered the tallest mass timber building in the world, and the construction is particularly multifaceted, utilizing a specifically fabricated set of interdependent building materials and finishes to meet structural and fire-safety regulations. The Brock Commons tower’s hybrid structural system brings to light another valuable lesson: that above certain heights—ten to twelve stories—the lightness of mass timber construction becomes a liability with regard to wind loads. The lack of physical mass at the highest parts of a prototypical timber tower results in increased deflection from wind loads. Ola Jonsson, partner architect at Swedish architecture firm C.F. Møller, recommended architects “go back to thinking about construction when designing mass timber structures,” as a way of rethinking approaches to dealing with difficult-to-manage structural conditions. He added, “It’s so early [in the adoption of mass timber technologies] that few really know how to do it well.” The architect said that with certain tall timber tower projects the office is working on, designers had to develop new massing strategies to limit wind loads. Jonsson continued, “Many engineers lack experience in mass timber, so architects have to become central figures in construction and design during this early phase of adoption.” The firm is currently developing over ten mass timber projects, an emerging body of work that came out of earlier mass timber competition entries developed by C.F. Møller that took the world by storm. C.F. Møller recently entered into a partnership with HSB Stockholm—Sweden’s largest housing association—to design a series of new mass timber housing towers, including the 34-story Västerbroplan tower designed with concrete cores and wraparound terraces. The tower’s columns and beams will consist of a blend of CLT and solid timber. The building’s terraces will come with integrated exterior curtains and will be fully enclosed by a steel superstructure containing glass panels. The tip of the building is designed to dematerialize as it steps back along two facades, creating a series of exposed terraces and planted areas. Like Brock Commons, Västerbroplan tower features a hybrid structural system that is “resource-effective,” according to Jonsson, meaning both lightweight and rigid. The firm is also at work on a 20-story bundled housing tower called Hagastaden for HSB Stockholm, this one designed as part of a new quarter of the city that will contain mixed uses and generous pedestrian areas. The tower features varied floor heights designed to accommodate divergent uses like student flats, penthouse apartments, and typical family-occupied units. Aside from the firm’s multiple mass timber projects, C.F. Møller is working as part of an interdisciplinary research team that is developing new strategies around mass timber towers rising 20 stories or more. The group—backed by SP Technical Research Institute of Sweden, Växjö Municipality, and Linnaeus University, among others—will investigate mass timber construction from a fire-safety, life cycle, and construction technology perspective. Regarding the research project, Jonsson explained, "Massive wood constructions give urban planners, architects, and designers great possibilities to develop innovative and sustainable architecture,” adding, "but a broader knowledge and more practical experience in the industry is needed." Another paradigm-shifting impact mass timber construction has had on European building methods relates directly to the construction process. Because mass timber elements are factory-produced to order, the relationship between engineer, builder, and architect is extremely integrated. Cory Scrivner, mass timber specialist with Canadian mass timber manufacturer Structurlam, said, “For us, it’s all about the 3-D model. [Digital modeling and coordination] are all done before we go into production in the factory: Everything has already been approved by the architect, engineer, and our team.” Scrivner explained further that the intense coordination was necessary, as “we are designing a building made from components that are accurate within one to two millimeters of the digital model.” The designers behind Brock Commons utilized Structurlam as the mass timber manufacturer for the project. The advanced level of project coordination and off-site fabrication meant that project was finished roughly four months ahead of schedule, with a time-lapse video on a project website showing construction crews erecting upward of two floors per day. The first story for the project was built from cast-in-place concrete, while the remaining 17 stories are built in mass wood. The structural system utilizes glulam columns, steel connectors, and a two-way spanning CLT flat-slab. The design creates a floor beam–free structure that could be erected start-to-finish in nine and a half weeks. The rapid-fire construction time line, however, comes at the expense of longer planning and design phases prior to any work boots hitting the job site, as the teams must become absolutely synced prior to fabrication. Waugh of WTA explained that often with timber buildings, the firm asks its clients to “give us more time now [in the planning stages of construction] and we’ll save you even more time on the back end.” Waugh added, “The better programmed the construction process, the faster and more accurately the buildings come out.” Waugh said that after erecting several mass timber structures, the firm had “gotten so much better at it” than when they first started. One area of improvement has been material usage, which decreased with each project as the structural capabilities of mass timber have been further explored, tested, and certified. The Dalston Station project mentioned earlier, for example, utilized about two-thirds as much timber as the firm’s first mass timber project erected a decade ago. Part of the reason for the improvements, Waugh and Jonsson agreed, results from designers’ greater awareness of and comfort with the construction process. “To design well in mass timber, you need an architect who wants to understand that the nature of [the architect] is one of a ‘master builder’ as well as one of a ‘master designer,’” Waugh explained. Since mass timber construction methodologies are based on kit-of-parts assembly systems of mass-produced panel types and structural elements, there has been increased interest among European and Canadian firms in building high-density mass timber housing. These experiments have positive implications for the many American cities burdened with housing shortages and long project-approval times. Waugh explained that WTA’s focus rests on expanding the abundance of available housing through mass timber construction. He said, “We design everything in our office now as if it was a mass timber project. Concrete projects are becoming more and more rare.” Several projects in the works, like Shigeru Ban’s recently proposed 19-story Terrace House in Vancouver, Michael Green Architecture’s 35-story Baobab building in Paris, and PLP Architecture’s 80-story addition to the Barbican housing estate in London, point toward a wider adoption of tall and supertall mass timber housing towers. With faster construction times and fabrication that can occur in tandem with permitting, mass timber has the potential to help cities add housing rapidly, safely, and efficiently. Waugh added, “Humanity is becoming more urban, so the principal job of an architect in the 21st century is to develop high-density urban housing. In an era of climate change, it behooves you [as a designer] to reduce the amount of carbon emitted. Again, for us, mass timber is a way to do that.”