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 | 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 | Jan 13, 2016 | News
The American Wood Council says the International Code Council (ICC) Board of Directors approval of the formation of a Tall Wood Building Ad Hoc Committee.
The committee will be made up of stakeholders, code officials and other interested parties. The committee will study tall wood construction and may develop code changes to be submitted for the 2021 International Building Code. Tall wood is an industry term to identify the use of cross laminated timber (CLT) and other heavy timber manufactured wood products in building heights greater than six stories.
“Other nations have already seen the benefits of tall wood construction – from the low carbon footprint, ease of construction and reduced construction time.
“Wood products are made from renewable resources found abundantly in North America. AWC petitioned ICC for creation of the committee to research the building science of tall wood buildings, and are pleased that it is moving forward. This is an important step toward the advancement of tall wood in the United States, a carbon-sequestering alternative in construction.”
From Woodworking Network: https://www.woodworkingnetwork.com/news/woodworking-industry-news/tall-wood-building-committee-will-work-2021-global-building-codes
