by Web Editor | Aug 17, 2018 | News
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.
Read more on this from The Architects Newspaper at https://archpaper.com/2018/08/oregon-legalize-mass-timber-high-rises/.
by Web Editor | Dec 4, 2017 | News
Congress Gears Up For A Fight Over Mass Timber Legislation
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.
From The Architects Newspaper: archpaper.com
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by Web Editor | Jul 19, 2017 | News
The International Code Council Ad-hoc Committee on Tall Wood Buildings provided five fire scenarios that were tested in each of the two one-bedroom apartments constructed using mass timber in a multi-story apartment building. The test scenarios included various arrangements of exposed and unexposed cross-laminated timber (CLT) with open doors between living and sleeping areas while the effectiveness of automatic sprinkler systems was simultaneously evaluated.
Test 1: a mass timber structure fully protected with gypsum wall board was subjected to a large furnishings and contents fire. The test was terminated after three hours without significant charring on the protected wood surfaces of the structure.
Test 2: approximately 30 percent of the CLT ceiling area in the living room and bedroom were left exposed. The test was terminated after four hours, providing additional time to determine if there would be any significant fire contribution from the exposed CLT. Notably, once the furnishings and contents had been consumed by the fire, the exposed CLT essentially self-extinguished due to the formation of char that protected the underlying wood.
Test 3: parallel CLT walls were left exposed, one in the living room and one in the bedroom. Similar to Test 2, once the apartment furnishings and contents had been consumed by the fire, during which a protective surface of char formed on the CLT, the mass timber surfaces essentially self-extinguished.
Test 4 and 5: examined the effects of sprinkler protection. For both tests, all mass timber surfaces in the living room and bedroom were left exposed. Test 4 demonstrated that under normal operating conditions, a single sprinkler easily contained the fire. For Test 5, the fire was allowed to grow in the compartment for 23 minutes before water was supplied to the sprinklers which quickly controlled the fire.
From Woodworking Network: https://www.woodworkingnetwork.com/architectural-products/cross-laminated-timber-fire-testing-sees-promising-results?ss=news,news,woodworking_industry_news,news,almanac_market_data,news,canadian_news
by Web Editor | Jul 17, 2017 | News
A two-story cross-laminated timber (CLT) structure is being subjected to the forces produced by a 1994 6.7 Northridge earthquake. The engineered simulation is expected to reveal ways in which tall wood buildings could survive damaging earthquakes.
Workers constructed a 22-foot tall wood test structure on UC San Diego’s shake table, a device for shaking structural models or building components with a wide range of simulated ground motions, like earthquakes.
Led by the Colorado School of Mines (CSM), the new test will examine the viability of constructing quake-resistant CLT buildings that could be as tall as 20 stories high.
“We are working to minimize the amount of time buildings are out of service after large earthquakes,” CSM engineer Shiling Pei said in a statement. “We are also focused on cutting the costs required to repair them.”
Cross-laminated timber advocates say it can be used to construct buildings of equal strength and fire-resistance as those made of steel and concrete. It has also fueled the passions of architects and environmentalists, who believe it to be a much greener method for housing the world’s growing population.
From Woodworking Network: https://www.woodworkingnetwork.com/two-story-cross-laminated-timber-simulated-67-earthquake?ss=news,news,woodworking_industry_news,news,almanac_market_data,news,canadian_news
by Web Editor | Apr 5, 2017 | News
The U.S. Forest Service is working to build markets for innovative forest products. One of these products, cross-laminated timber, also known as CLT, offers an opportunity for raising tall buildings with wood, opening up a completely new market for wood products.
And there’s tremendous opportunity to increase the market share for wood-based construction. Because of its high strength, CLT is an advantageous alternative to traditional building materials such as concrete, masonry, and steel. Because CLT panels resist compression, they are well-suited for building multistory structures, especially mid-rise buildings. Made from layers of dried lumber boards, stacked in alternating direction at 90-degree angles, glued and pressed to form solid panels, CLT has exceptional strength and stability and can be used as walls, roofs, and floors.
Additionally, CLT is highly resilient to fire, earthquakes, and even explosions. In fact in a recent series of live blast tests, CLT passed with flying colors. An examination of the results showed that the CLT structures suffered less degradation than expected and might outlast concrete and steel.
In terms of fire, CLT is like using a large log to start a campfire—it doesn’t ignite easily. And when it does burn, a char layer forms on the outside, protecting the inside and allowing the wood panel to maintain its structural integrity during fire scenarios.
Researchers have conducted extensive seismic testing on CLT and found that the panels perform exceptionally well in multi-story applications. When a seven-story CLT building was tested on the world’s largest shake table in Japan, it survived 14 consecutive earthquake simulations with almost no damage.
From the USDA: https://www.usda.gov/media/blog/2017/04/04/build-better-stronger-faster-clt
