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Kaiser Group and Path Architecture designed Carbon 12. At the time it was built it was the tallest mass timber and cross-laminated timber in the country. CREDIT: ANDREW POGUE Strides In for Mass Wood Timber Tall Mass Wood Timber buildings have captured the design imagination of North America. As these buildings are poised to go taller, the leading company, Hilti North America, has stepped in with innovative ways to help promote fire safety.

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www.greenbuildermedia.com “The question for Hilti became, How long can a structural wood construction element withstand a fire within a building? Hilti has focused on this gray area because no approved firestop solutions existed.” —Neal Clemens, Marketing and Product Manager, , Hilti North America

wood-built future in tall buildings. ability to approach tall building from a From 2014 to the end of 2018, the modular standpoint results in reduced number of U.S. mass timber projects manpower and many other characteristics grew from fewer than 20 to well over that make CLT attractive to the building 400, reports nonprofit WoodWorks. And industry—and it’s not going away.” Forterra, a land conservation nonprofit, says that demand for CLT, which is used WITH INNOVATION COMES in Tall MWT projects, is expected to RESPONSIBILITY double every five years into the future. Perhaps the most important (and misun- The exponential growth of MWT derstood) aspect of MWT is its fire perfor- is good news for the building industry mance. People often think of wood as a because the technology offers faster quick-igniting object, like kindling. But CREDIT: ANDREW POGUE Carbon 12 shows off the beauty of wood with its exposed Douglas Fir panels doubling as finished ceilings. construction time, reduced on-site skilled the mass wood used in multistory build- Mass timber is the general term for labor requirements, generally lighter ings chars in the event of a fire, protecting large structural panels, posts, and beams weight potentially requiring less substan- the inner layers of wood from damage. HEN CARBON 12, A BEAUTIFUL EIGHT-STORY Cross-Laminated composed of wood. Products in the cate- tial foundations, beneficial thermal prop- In fact, according to “Mass Timber Timber (CLT) apartment complex was built in Portland, gory include CLT, Structural Composite erties, and positive environmental impact. Market Analysis,” by The Beck Group, Lumber, glue-laminated timber, and large “CLT technology is absolutely becoming “Recent laboratory burn tests of Mass Oregon, the country got excited about the future of Tall Mass section sawn lumber. The market for these more popular,” says Matthew Winston, Timber products have addressed Wood Timber (MWT) building. After Carbon 12’s 2017 debut, products in tall buildings like Carbon 12 is Testing and Approvals Engineer, Fire concerns regarding fire safety in large many on-the-boards projects got press as Portland—and growing rapidly—so rapidly, in fact, that Protection Engineering Team, Hilti North wooden structures. Mass timber struc- the building and scientific communities America. “And really that popularity tures far outperform stick framed struc- Wother cities, including Chicago, San Francisco, and Philadelphia—dreamed are struggling to keep up with the anal- started to rise in 2015, making a resurgence tures and, due to the charring effect, can of new ways to go taller with timber. Today, Portland has the country’s largest yses, best practices, and codes needed to with the green building and sustainability even outperform steel structures during ensure a smooth transition from building initiatives that design firms were looking very high temperature fires, in which concentration of mass timber buildings and has solid growth potential. with steel or post-tension concrete to a to bring into the construction world. The steel will melt, deform, and fail.”

2 Strides In Fire Safety for Mass Wood Timber Buildings Strides In Fire Safety for Mass Wood Timber Buildings 3 Hilti, the leading manufacturer of BUILDING CODES EVOLVE the use of MWT in tall buildings. worked through issues, Hilti While Winston points out that quite a for building designers and the inspectors internationally approved and tested fire- According to the International Code Based on favorable research results, continued to focus on firestop solutions. few Tall MWT buildings have gone up in who are tasked with signing off on fire- stop systems, monitored the growth of Council (ICC), “Tall Mass Timber” identi- ICC approved code changes to 2021 IBC “We asked ourselves, ‘How do we tie fire- places like Portland and Seattle, a large part stop systems in MWT buildings, but until MWT, and in particular CLT, and realized fies mass timber buildings constructed of allowing for Tall MWT. stop into the building of MWT, addressing of the inspection community is still waiting the assemblies are listed or certified, says its leadership in producing and testing mass timber elements that exceed current “For the 2021 IBC, ICC classified MWT these taller and bigger buildings?’ The code for a chance to review a MWT project. “For Winston, approvals will rest on project- firestop products had put the company height limits for wood buildings set by the within a Class IV building and then added gives requirements like it does for any example, I recently provided an analysis specific designs called Engineering in an excellent position to help propel the International Building Code (IBC). Until three more categories types--IV-A, IV-B, other type of construction, but you have of test data for in CLT to a design Judgments. “Typically, someone who mass timber industry forward. recently, building codes were the primary and IV-C. These categories allow fully to have rated assemblies and still meet team,” says Winston. “The initial firestop needs a firestop system would refer to “The question for Hilti became, ‘How barrier to the use of Tall Mass Timber encapsulated MWT buildings (IV-A) to go up the requirements for compartmentaliza- designs were provided in 2018 and now, a listing from a third-party certification long can a structural wood construc- because they were tailored to traditional to a maximum 18 stories depending on the tion,” Goldhammer says. “We have always in 2020, the design teams are sitting with body. To date, however, no such listings tion element withstand a fire within a building systems, such as steel, stick and partially encapsulated MWT had firestop through a rated assembly, so building inspectors [to review life safety.]” exist for firestops in MWT,” he says. building?’” says Neal Clemens, Marketing frame, and concrete. buildings (IV-B) to go up to a maximum of that’s not a big change. The challenge is Hilti wants to streamline the process With the goal of developing more data

In 2019, Katerra opened a 270,000-square-foot CLT factory in Spokane Valley, Wash. At full capacity, this factory will produce the highest When CLT members, such as this one being manufactured by Katerra, are tested by Hilti, they are built into mock-up assemblies with penetrations volume of CLT in North America–13,000,000 square feet of 5-ply panels annually. The factory also represents one of the largest CLT presses included. The testing plans are designed to show what happens when mechanical or is put through the floor to determine how to currently in operation globally, offering customers unmatched design flexibility. IMAGE BY KATERRA WWW.KATERRA.COM fire rate it. The tests include different CLT manufacturers’ products and different species of wood, which are tested in ovens. COURTESY HILTI

and Product Manager, Fire Protection, “In the 2018 code cycle, wood coali- 12 stories,” Goldhammer explains. that these new assemblies are not part “There has been a big push back around fire Hilti North America. “Hilti has focused on tions put forth proposed changes to The encapsulated buildings use of a listing/certification [such as UL or safety in tall wood buildings. On the one this gray area because no approved firestop include MWT,” says Edward Goldhammer, gypsum or other noncombustible prod- Intertek] so we can not obtain a firestop solutions existed.” Director of Codes and Approvals for ucts to add passive fire resistance, which certification without a certified assembly.” hand, design firms, the mass timber “Really the question around firestop Hilti North America. “The bulk of these is why they are approved for taller struc- industry and ICC code committees have HILTI GOES TO BAT started with Oregon State University, proposals were rejected because they did tures. The partially encapsulated build- paved the way; on the other hand, fire who had contacted SmartLam to build a not have enough data on fire performance ings are still safe, Goldhammer says. “There has been a big push back around Tall MWT the University had designed,” in tall buildings. As a result ICC agreed to “Even though the IV-B structure performs fire safety in tall wood buildings,” Winston inspectors, fire departments, and city says Clemens. “SmartLam said they could create an ICC Tall Wood Building Ad Hoc well, having the gypsum just adds another says. “On the one hand, design firms, inspectors have pushed back on life safety build it but asked the important question: Committee. The committee in conjunction level of safety.” the mass timber industry and ICC code issues and the lack of assembly ‘What about life safety?’” with the wood industry conducted a series Designers can opt for the IV-B structure committees have paved the way; on the certifications.” The building industry, antsy to put of large scale fire testing to demonstrate for designs that celebrate the wood look of other hand, fire inspectors, fire depart- wood to work in buildings of scale, turned how MWT performs in a fire. Based on this CLT building. Exposed Douglas Fir panels ments, and city inspectors have pushed —Matthew Winston, Testing and Approvals Engineer, to building codes and testing to maintain research the committee developed a set of can, for example, serve as unit ceilings. back on life safety issues and the lack of Fire Protection Engineering Team, Hilti North America the momentum of Tall MWT adoption. code change proposals to accommodate While the ICC and other stakeholders assembly certifications.”

4 Strides In Fire Safety for Mass Wood Timber Buildings Strides In Fire Safety for Mass Wood Timber Buildings 5 The tests were successful, helping show metallic penetrating items, ducts, and One critical reason that firestop testing firestops in CLT can perform well in cables with success. In joints, will in MWT is so important is to understand accordance with consensus consist mainly of flexible sealants, either how collars will perform standards. “The tested solutions have acrylic or silicone based, that accommo- when the MWT they are attached to begins allowed us to use Hilti testing as evidence date small amounts of movement. to break down under fire conditions. Hilti to demonstrate life safety building code PRODUCT SOLUTION: Intumescent wraps or collars are has successfully tested the use of collars requirements are met,” Blomgren says. High-Performance a unique firestop tool that excel when attached to exposed MWT floors. A key next step for Hilti is to work Intumescent Firestop protecting openings with with certification agencies to develop a FS-ONE MAX nonmetallic pipes. During the fire endur- pathway for MWT firestop listings. “Hilti ance test nonmetallic penetrating items has tested firestops in CLT assemblies This product seals most common through melt and break down, which leaves a with representatives from leading certi- penetrations in a variety of base materials void equal to the original size in including concrete, masonry, , and fication agencies as witnesses. These tests the opening. Intumescent wraps and mass timber. Appropriate for metal pipe have been positive, which has opened the collars are designed to expand at the time penetrations (copper, steel, and EMT), pathway for discussing how to approach nonmetallic pipes start to break down to

COURTESY HILTI COURTESY insulated metal pipe penetrations (steel Hilti engineers test CLT assemblies to UL 1479 (ASTME 814) for penetrations and listings,” Winston explains. “We have and copper), and plastic pipe penetrations fill the void space created. UL 2079 (ASTME 1966) for joints. The photo above shows a MWT assembly as it is done a lot of work to find safe solutions, (closed or vented). The sealant is easy Testing for intumescent wraps in MWT PRODUCT SOLUTION: removed from the at the end of a UL 1479 fire endurance test. and it is important for designers and to use, water based, paintable, ethylene involves wrapping the nonmetallic pene- Speed CP 653 BA building officials to have clear options glycol free, and offers industry-leading VOC trating item and then inserting it into the for CLT assemblies, Hilti has worked with applying different firestop material, for firestops in CLT assemblies. The goal results. Visit: FS-ONE MAX annular space within the MWT assembly. For use with concrete floor rated up to three Katerra, Nordic, and other manufacturers and prepping the assembly for testing,” is to avoid the use of a firestop solution Intumescent collars are attached to the hours and gypsum walls rated up to four hours, and MWT assemblies for up to 1¹/₂ on firestop solutions for CLT since 2017. Winston says. that was not tested, and the best way to in most cases and allow contractors to be outer surfaces of the MWT assemblies hours, this product is a re-penetrable cable “We requested Hilti provide tested fire- Tests were performed at the Hilti accomplish this is to have publicly avail- reactive to changing jobsite plans. (to both surfaces for walls or the bottom management device electrical and premise stop assemblies for use on our first CLT North American Testing and Development able firestop listings in CLT as we have With penetrations through MWT, surface only for floors) using wood screws. wiring, as well as low-voltage and datacom. projects—The Postmark, Lifebridge, Center in Irving, Texas. Engineers focused for concrete, gypsum, and other building firestop sealants are often intumescent It offers fast installation, easy penetration Amberglen, and The Grove,” says Hans- on two standards applicable in the United systems. I am hopeful that we can reach (designed to expand with heat) and paired and re-penetration, the industry’s best “Air Erik Blomgren, PE, SE, Director of Testing States: UL 1479 (ASTME 814) for pene- this goal with our certification partners with insulation to fill the Movement” ratings, Low L-ratings. Test in and Characterization, Katerra. trations and UL 2079 (ASTME 1966) for in the next year.” annular space around penetrating items. accordance to UL 1479, ASTM E 814, CAN/ Hilti put its state-of-the-art research joints. For Canada approvals, Hilti tested Hilti has tested firestop sealants with ULC-S115. Visit: Speed Sleeve CP 653 BA facility and the expertise of its engineers to CAN/ULC S115, both in-house and with FIRESTOP PRODUCTS ARE THE KEY to work testing firestop solutions on CLT external partners. Hilti provides these Firestop solutions are the key to why Firestop devices bring many advan- specimens. “Together we designed the test types of collaborative tests for a variety CLT assemblies continue to pass Hilti’s tages when planning and jobsite coordina- plan and did all the research necessary to of customers. “We provide services, prod- rigorous lab tests. “Firestop is important tion can accommodate their installation. test the assemblies in the lab, including ucts, and custom testing plans for each because as we approach 2021—when they Hilti’s firestop drop-in device is a great creating all the openings for penetrating project to help Katerra,” Clemens says. actually adopt fire protection for tall mass PRODUCT SOLUTION: example for MWT of a firestop device that items like PVC drain pipes or conduit, This work should inspire confidence. timber into the building codes—there Firestop Drop-In Device can accommodate a variety of metallic needs to be a way to balance going higher CFS-DID and nonmetallic penetrating items, can be and higher with safer and more effec- installed on the jobsite or accommodate tive structures,” says Clemens. Winston An out-of-the-box, one-step firestop solu- modular design with factory installation, agrees, and says Hilti’s firestop prod- PRODUCT SOLUTION: tion for a variety of pipe materials and and simplify inspection. ucts are crucial if the building industry Firestop Top Track Seal diameters, this product helps reduce labor The device contains intumescent costs and increases productivity. It offers continues to push the vertical boundaries. CFS-TTS strips at the bottom of a steel sleeve with integrated moisture and smoke seal and Firestop products that have been tested an integrated flange. The device flange is CFS-TTS is a preformed polyurethane fire- quick install, and is easily identifiable to in MWT assemblies can be grouped into attached to the top surface of the MWT stop device designed to be a versatile building inspectors. The device is for use in three major categories: sealants, intumes- floor. The intumescent strips are located solution for fire-rated assemblies on flat MWT, concrete, hollow core, and metal deck cent wraps or collars, and firestop devices. on both the inside and outside of the concrete construction. Designed to saddle slab thicknesses ranging from 2 ½” to 12 ½”. Firestop sealants are popular on over top track without additional folding, Options for fastening include gas actuated sleeve. This affords protection of the jobsites because they are simple to install taping, or gluing, the product achieves a fasteners, metal hit anchors, and Kwik con annular space around penetrating items once the opening and penetrating item, or durable and reliable system tested in accor- screw anchor systems. For MWT assemblies in the sleeve, and it protects the opening joint, has been made. Sealants are the last dance with UL2079 5th Edition and CAN/ the device is fastened with wood screws. in the MWT around the sleeve by filling item to be installed for a firestop system ULC-S115. Visit: Top Track Seal CFS-TTS Visit: Firestop Drop-In Device CFS-DID the space with intumescent material.

6 Strides In Fire Safety for Mass Wood Timber Buildings Strides In Fire Safety for Mass Wood Timber Buildings 7 IMAGE BY KATERRA WWW.KATERRA.COM KATERRA BY IMAGE

Katerra is constructing the 150,000-square-foot Catalyst Building in Spokane’s new South University District. This is the first project to receive CLT from Katerra’s newest factory and the first office building in Washington State to be constructed from CLT. The Catalyst will be connected to an energy and resource sharing eco-district that serves as a bridge between Spokane’s downtown core and the growing U-District.

In joints involving MWT, Hilti has had success with firestop devices. One example is the joint between gypsum board and the bottom surface of a MWT floor. This joint is called a head-of-wall joint, and it can be protected with Hilti’s Firestop Top Track Seal. This firestop device is placed over the ceiling runners used for the walls prior to attaching the framing to the bottom of the MWT assembly. Intumescent flanges on the device then hang over the ceiling runner, and once gypsum board is installed, fill the space between the gypsum board and MWT floor.

STREAMLINING FOR THE FUTURE Clemens reminds. “We don’t have to timber, specifically CLT, as the backbone for While Hilti is the undisputed leader in reinvent the wheel or create brand-new future generations of high-performance, firestop solutions for MWT building—as products to support the industry, to help low-carbon buildings,” says Blomgren. well as a tireless champion of streamlined everyone on site.” “Mass timber is a technologically advanced adoption of Tall MWT—the company has Looking to the future, Clemens says and sustainable product that offers a shift a broader role. that Hilti’s suite of products, expertise, towards greater productivity through “We are Hilti, and we are committed and customer support put the company prefabrication. When sourced from well- to fire protection,” Clemens emphasizes. in an excellent position to help building managed forests, mass timber can benefit We also offer more than that. Think of us designers dream up ever more exciting the environment and the built environment as mass timber everything—everything a Tall MWT projects. by contributing to forest health, reducing firestop professional would need to install “One of the most exciting things about the carbon footprint of buildings and in MWT or other types of construction, the mass timber industry is prefab,” increasing the well-being of its occupants.” we can do.” Clemens says. “Companies can create “From my side, looking at the future, The streamlining includes the tireless assemblies off site, put them on a flatbed, we will continue to support projects lobbying and grueling data gathering and they go up just like puzzle pieces on directly,” says Winston. “For manufac- for listings and code approvals, as well site. All the construction concerns of the turers and organizations that want to as the company’s commitment to be the industry—budget, safety, timing, pay, take mass timber to the next level, such as one source for developers and designers. and income—are all tied to schedule, and in modular buildings, we will help those “We have developed products for concrete we can help solve that.” companies bring efficiency to the building and steel construction that work for wood, Katerra and other manufacturers are process and provide firestop solutions such as tools, screw fastenings, anchors,” bullish about the future. “We see mass that support the life-safety mission.” n

8 Strides In Fire Safety for Mass Wood Timber Buildings