From the Field: Mass Timber Update
At 12 stories, Akari House was already destined to be the tallest mass timber building in Seattle — but the developer and project team had even loftier goals. With an additional six stories, Akari House is now slated to stand 18 stories tall, a first-of-its-kind structure in Seattle utilizing the newly-adopted mass timber code provisions.
Mass timber mid- and high-rise construction are now possible due to recent changes to the state building code, expanding the use of wood materials into new building types that previously would have been off-limits. (We wrote about these changes in edition no. 5 and have hosted presentations regarding new code applications). Akari House is designated Type IV-A, which allows wood construction up to 18 stories and 270 feet.
The 135-unit residential tower will utilize an all-timber gravity system with mass plywood panels and a concrete core. The project will incorporate design elements and materials that support its natural aesthetic complemented by lush landscaping and unparalleled views from its roof deck and coveted First Hill location.
Constructed is expected to begin Fall 2020.
Project Team: Owner: Pryde Corporation / Architect: Clark | Barnes / Structural Engineer: Coughlin Porter Lundeen / General Contractor: Swinterton Mass Timber / Mechnical & Electrical Engineer: Glumac Inc.
Kellogg Middle School
The new Kellogg Middle School in Shoreline is the first project in the nation to use an acoustic dowel laminated timber (DLT) system for structure, finish, and sound control.
Instilling a sense of environmental stewardship in students is essential to the school’s design. The building will serve as an ecological learning tool as digital dashboards display real-time data on the amount of energy used and produced, water savings, and air quality monitoring.
The school evokes a warm and natural environment by exposing the DLT panels as well as the supporting glulam beams in the roof/ceilings of the entryway, commons, and library. The largest wood panels are nearly 40 feet long by 6.5 feet wide; prefabricated offsite by StructureCraft, they took just two weeks to erect. According to Mahlum, it’s estimated that the total carbon sequestered in Kellogg’s wood structure is equivalent to CO2 emissions from 32,500 gallons of gasoline. (That’s like filling a 12-gallon car tank well over 2,600 times!) Read more about the project on Malum’s blog.
The new middle school is expected to open in Fall 2021.
Project Team: Owner: Shoreline School District / Architect: Mahlum / Structural Engineer: Coughlin Porter Lundeen / General Contractor: Hoffman Construction / Mechanical & Electrical Engineer: Hargis
Left image courtesy of Mahlum
Located in Fremont, this new five-story office building will rise to the City of Seattle’s Living Building Challenge (LBC), a pilot program that allows departures from the Seattle Land Use Code by integrating advanced sustainability measures. (In other words, it allows more floor area and additional height in exchange for green design features.) LBC organizes the program into seven performance areas: Place, Water, Energy, Health and Happiness, Materials, Equity, and Beauty.
The design focuses on reducing energy use by at least 25% from that of a comparable mixed-use office building. Multiple structural options meticulously considered carbon sequestration, cost, and complex programming needs – ultimately deciding on a DLT mass timber system. The building qualifies for an additional 15 feet of height through integration of additional LBC sustainable design elements, including salvaged and locally sourced building materials, a 250,000-gallon rainwater cistern, rooftop beehives, and a 100-kilovolt-ampere solar panel array, for total building height of 60 feet.
Construction begins soon and the project is expected to be complete Spring 2022.
Project Team: Owner: SRM Development / Architect: Weber Thompson / Structural Engineer: Coughlin Porter Lundeen / General Contractor: SRM Development / Mechanical & Electrical Engineer: WSP Seattle
Renderings courtesy of Weber Thompson