Posts tagged with "Cross-Laminated Timber (CLT)":
LEVER Architecture’s Thomas Robinson discusses the impact California could have on the timber industry
We are witnessing a revolution in how we build with engineered timber in the United States.
In January 2019, the International Code Council (ICC) approved changes that would allow high-rise wood buildings in the 2021 International Building Code (IBC). Oregon and Washington were early adopters of these code changes, and Denver, Colorado, recently followed suit. Other states and municipalities are expected to adopt the 2021 IBC timber provisions early, but it is anyone’s guess what California will do. Will the state decide to adopt now, or will it wait till the code becomes part of the new issuance of the 2021 IBC? This is an important question not just for California, and by extension the City of Los Angeles, but also for the future of mass timber in the U.S. and beyond. California standards and codes transform markets, and a mass timber movement in the U.S. without the state that is also the world’s fifth-largest economy is not going to move the needle fast enough. The opportunity to scale a low-carbon, renewable supply chain to address catastrophic climate change is closing quickly, and it is time for California to step up and demonstrate the progressiveness and leadership that have been key to its prosperity.
What does early adoption mean in practice? Today, an architect in Oregon or Washington who follows the provisions of the new IBC can stamp drawings to build a timber building up to 270 feet in height as of right. This is a significant change. Just over four years ago, my firm’s design for a wood high-rise called Framework was selected as one of two winners of the first U.S. Tall Wood Building Prize Competition. At that time, there was no code path in the U.S. for wood buildings over 75 feet. To receive a permit, our team of designers and engineers worked with the State of Oregon on a performance-based design process. Partly funded by the competition prize, this process included 40 tests on full-scale timber building assemblies to demonstrate their fire, seismic, structural, and acoustic performance relative to high-rise life-safety requirements. It was a fascinating, exhausting, and exhilarating experience, and we are proud that this work and research impacted the timber code changes. Thanks to the new code provisions, it is unlikely that another design team will ever have to go through this process in quite the same way again.
Early adoption of the timber code provisions isn’t just about tall buildings, though—it is a critical opportunity to encourage wider investment and innovation in sustainable mass timber development of all scales. Why should California (or any place else) care about mass timber construction? Building with engineered timber products addresses our most pressing global challenges. It has the potential to decrease carbon emissions relative to construction, spur rural economic development, encourage forest practices that prevent fires, and increase the speed at which we can deliver projects, including much-needed affordable housing. The promise of a major market like California supporting mass timber construction will be an incentive for manufacturers to invest in a more advanced supply chain, back new research, and encourage more sustainable forest management. California’s early advocacy of renewables and electric vehicles moved the market (see Tesla), and I believe it could have a similar impact on the development of mass timber.
We are currently in the permit process for one of the first multistory office buildings in Los Angeles with a cross-laminated timber (CLT) floor system. The building is essentially a hybrid, with CLT floors and steel columns and beams. It meets the current code and does not use the provisions of the 2021 IBC because the highest occupied floor is not over 75 feet. That said, it is still a 125,000-square-foot building—not a small undertaking. We have been working closely with Los Angeles authorities and our engineer to clarify and explain how the CLT performs structurally in the project and how it fits within the current code. We have made incremental steps that will allow for subsequent projects to better navigate permitting this type of building, as well as open up options for multiple CLT suppliers to serve the Los Angeles market. I believe these small steps are significant, but I know that my team could have gone further faster if California had already adopted the new timber provisions. Building officials in California are justifiably cautious. The optics of approving tall wood construction as the state faces devastating wildfires is difficult. However, moving in this direction creates a market that will advance the sustainable forest management that prevents these fires in the first place. If we are serious about addressing the major environmental issues of our time, we need California to adopt the 2021 IBC now. We are simply running out of time.
Of course, there is more to do. I believe as architects we must rethink design as a wider ecosystem of environmental and regional economic choices. Where our materials come from and how they are produced should drive and inspire our designs. This is not a limitation but an invitation to innovate with regional, renewable materials to create more compelling architecture that truly addresses both local and global issues.
Thomas Robinson is the founder and principal of LEVER Architecture.
While many cross-laminated timber (CLT) buildings have tested the vertical limits of the product, San Francisco–based architecture firm WRNS Studio recently set a record by designing North America’s largest CLT building in floor area. At over 644,000 square feet, the firm’s addition to Microsoft Silicon Valley, part of a larger renovation of the Moutain View campus, demonstrates CLT’s potential as a building material for expansive horizontal structures.
Given how few CLT projects currently exist in Northern California, the mixed-use building’s construction required thorough coordination between the project team and the local building authority to determine the optimal methods for engineering with the product. Extensive research was required to ensure that the swaths of exposed CLT would achieve fire ratings suitable for a building of its size in blaze-prone California. Local engineering firm Holmes Structures developed lightweight CLT floor plates that conceal the building’s immense power and data infrastructure beneath a thin top layer of cement. These CLT-concrete composite slabs require few load-bearing beams and columns, allowing copious amounts of sunlight to illuminate the building's expansive interiors.
In an effort to reduce construction waste, WRNS renovated two existing buildings on-site while reusing the materials of the remaining buildings as the foundation of the two-story CLT structure. Over 345,000 square feet, or 2,400 tons, of CLT panels are used throughout the campus, representing more than half of the project’s total structural components.
The new, low-lying structure was designed to complement its natural surroundings through the addition of an occupiable living roof, a series of interior courtyards, and on-site trails that lead to nearby Stevens Creek. Every workspace within the building will have direct access to an outdoor space while allowing its occupants to precisely control airflow, temperature, and lighting within their individual working environments with minimal energy use.
Construction began in December 2017 and is expected to be completed by fall 2020.
The origins and guiding principles of Portland-based Hacker Architects stem from the six years founder Thomas Hacker spent working for Louis Kahn, an architect who knew how to match dramatic siting with phenomenal material palettes. Hacker has since retired, but the firm has expanded to a staff of over 60 people and continues to treat each project as an opportunity to mix contextualism with the latest in efficiency and sustainability. The firm is known for its innovative uses of cross-laminated timber, a favorite because of the material’s quick renewability and capacity to function as a carbon sink; the firm also employs a wide range of locally sourced materials to reduce waste and incorporates passive heating and cooling methods whenever possible.
Hacker Architects’ leaders feel they are in service to the public and have become specialists in the design of libraries, museums, and other cultural institutions. The handful of private buildings they’ve designed, however, are no less representative of the firm’s dual interests in siting and materiality. Inspired by local history, natural scenery, and the imperative to reduce our carbon footprint, Hacker Architects sets examples for the industry with every project.Lakeside at Black Butte Ranch
Surrounded by the scenic Cascade mountain range and the Deschutes National Forest in Central Oregon, Lakeside adds a sprawling recreational and dining complex to the rustic-modernist resort atmosphere of Black Butte Ranch. The project used a $11.5 million budget to replace an aging pool facility with a 15,000-square-foot design that heightens the experience of transitioning from the rugged outdoor landscape to the calming resort.
Douglas fir is the primary structural component for the project, while the interior and exterior are almost entirely clad in locally sourced cedar, a material in common use in the Pacific Northwest because of how it gracefully weathers. The firm envisioned the building as an “aperture for the site,” framing views that might strengthen connections between the ranch and the vast landscape beyond.
Bayview/Linda Brooks- Burton Library
Replacing a branch library dating from 1969 in the historically underserved neighborhood of Bayview in the southeastern portion of San Francisco, the Bayview/Linda Brooks-Burton Library was completed in 2013 and designed to be an open and inviting space for the community it serves. Many of the library’s design gestures are a nod to the neighborhood’s African and African American past, including the street-level window walls adorned with illustrations of the area’s history, the kente cloth–inspired exterior paneling, and the space allotted throughout the library for works by local artist Ron Moultrie Saunders.
The firm designed the library to look inward, with a courtyard at the center large enough to host events; thanks to the floor-to-ceiling windows that surround it, the courtyard provides generous natural light and views throughout the interior spaces. The library contains several environmentally efficient features that helped it achieve LEED Gold status, including passive ventilation and air-filtration systems in the exterior walls, embedded photovoltaic arrays, and a green rooftop that filters stormwater runoff using native grasses and perennials.
When tasked with creating a permanent home for the Oregon Bach Festival, an annual event in Eugene, Oregon, that celebrates the works of Johann Sebastian Bach, Hacker Architects combined an office space with a double-height rehearsal room acoustically designed to function like the musical instruments that it contains. A wood panel system made of tongue-and-groove Accoya boards allows the tops of two of the rehearsal space’s walls to bend in a way that provides abundant natural light from above while also preventing excessive audial buildup in the lower portion of the room.
Visually distinct from the cubic rehearsal space is the office bar, a lower-slung, redbrick building designed to match the older buildings on the University of Oregon campus. Many of its windows are operable, permitting natural ventilation while reducing the demand on the building’s active heating and cooling systems.
Sunshine Canyon Residence
One of Hacker Architects’ few residential projects—as well as one of the firm’s smallest, at 2,200 square feet—the Sunshine Canyon Residence was built in the hills outside Boulder, Colorado, to replace its client’s previous home, lost in the Fourmile Canyon Fire near the site in 2010. To preserve the landscape, the majority of the house is supported by narrow steel columns that minimized the amount of construction work on the site. Given that the house is in a cold climate that receives an abundance of annual sunlight, its windows face south to maximize solar gain and reduce the need for active heating.
The materiality and formal simplicity of the home were inspired by the abandoned mine shafts, rusted steel mining structures, and naturally occurring granite bordering the site that resurfaced after the fire. The majority of the exterior is clad with corrugated steel and untreated Ipe, both of which are designed to patina over time, like the nearby mining equipment. The interior is lined with clear vertical-grain fir that recalls the trees on the site while subtly changing in shifting daylight.