by Web Editor | Oct 31, 2018 | News
Prescriptive requirements for wood structures up to 18 stories were among the additions preliminarily approved for the International Building Code following the work of the International Code Council’s ad-hoc Tall Wood Buildings Committee.
Wood is widely recognized as a carbon-neutral building material, but its use as a structural material has been mostly limited to residential and low-rise buildings due to its combustible nature. Through recent advances in manufacturing and engineering, wood in the form of mass timber products is increasingly attracting interest as a structural system for tall buildings.
Portland, Ore., recently saw the completion of the eight-story Carbon12, currently the tallest wood building in the United States. Still, progress has been slow in this country as compared to Europe or Canada, where the 18-story-tall Brock Commons, in Vancouver, stands as the tallest timber structure in the world. One significant issue inhibiting widespread adoption in the U.S. is prescriptive building codes, which currently limit the height of wood buildings to 85 feet, or six stories. In December 2015, the International Code Council (ICC) formed an ad-hoc committee to study the impact of tall wood buildings on the building code with the membership voting on the adoption of proposed changes on Oct. 24.
The ICC’s International Building Code (IBC) classifies a high-rise building as any building with an occupied floor 75 feet above the lowest level at which fire department vehicles can access. The 2018 IBC defines heavy timber structural members as Type IV construction, which also includes a range of wood products, such as solid sawn timber, glue-laminated members, and composite wood members. The term mass timber, however, comprises both heavy timber as well as engineered products, many of which the IBC does not reference, such as cross-laminated timber (CLT).
Heavy timber construction is currently limited to a height of 85 feet. Architects can design taller wood structures, but they must demonstrate that the design meets the prescribed code and performs as well or better than a similar concrete or steel structure. This can be a costly and time-consuming process, requiring extensive testing and documentation on the part of the design team and building owner.
Read more on this from Architect Magazine at https://www.architectmagazine.com/technology/support-for-tall-timber-reaches-new-heights-in-the-building-code_o.
by Web Editor | Oct 24, 2018 | News
From October 21-27, 2018, we celebrate the value of America’s forests and recognize how vital they are to our well-being and national prosperity during National Forest Products Week. This week is recognized each year by a Presidential proclamation. At the USDA Forest Service, we work year round to create new opportunities for wood products that contribute to diversified rural economies and support sustainable forest management.
By supporting forest products markets, we have the opportunity to create safer communities by reducing wildfire risk, supporting rural economic development, and contributing to a more sustainable building sector. The Forest Service is working to develop the U.S. market for cross-laminated timber, or CLT, and other mass timber technologies.
CLT is a made from several layers of dried lumber boards stacked in alternating directions, glued and pressed to form rectangular panels. These panels have exceptional strength and stability and can be used as floors, walls and roofs in building construction, replacing or used along with traditional building materials such as concrete and steel. In fact, the International Code Council is examining whether or not tall wood buildings up to 18 stories will be included in the 2021 International Building Code. A final decision will be made later this year.
The state of Oregon has already adopted the proposed provisions for the International Code Council under its Statewide Alternate Method, and Washington State legislation already embraces mass timber construction. The U.S. Department of Defense is already using CLT in some of its on-base housing because of the incredible resiliency of the materials and their resistance to explosive forces.
We are on the precipice of major momentum in the marketplace with mass timber, with four factories in production, including two making architectural grade CLT; five factories coming online (either under construction or just completed); and three more factories recently announced in eight states. Compounded with the upcoming code decisions, we expect to see many more mass timber and CLT buildings in the near future.
From the USDA: https://www.usda.gov/media/blog/2018/10/22/forest-service-celebrates-cross-laminated-timber-during-forest-products-week
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 | May 4, 2018 | News
The International Code Council’s (ICC) Committee Action Hearings in Columbus, Ohio, have concluded with a clear endorsement of building codes that will enable the use of mass timber technologies in buildings ranging up to 18 stories. Though taller mass timber buildings are currently being built under various local codes, this move by the ICC ensures that model code provisions will be available to many more building officials.
Mass timber structures are generally built with large panels made of cross-laminated timber (CLT), nail-laminated timber (NLT), glue-laminated timber (Glulam) or structural composite lumber (SCL). The greater availability of CLT has provided new options for builders.
“The strength and fire resistance performance of mass timber structures is well understood and supported by substantial testing and data,” said Stephen DiGiovanni, P.E., Chair of the ICC’s Ad Hoc Committee on Tall Wood Buildings and fire protection engineer for the Clark County (NV) Department of Building and Fire Prevention. “As taller mass timber buildings become more widely deployed, it’s important that the International Building Code and the entire family of I-Codes remains at the forefront of emerging construction technologies, and continues to provide building and fire code officials with the tools they need to ensure the safety of the public and first responders.”
All buildings under the International Building Code (IBC) must meet specified fire performance standards, whether built of steel, concrete or mass timber. The 14 code provisions passed out of the ICC Committee Action Hearing established new fire resistance standards and procedures for mass timber that are more rigorous than comparable steel and concrete structures.
From Civil+Structural Engineer: https://csengineermag.com/code-officials-move-update-ibc-tall-mass-timber-buildings/
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
