By Steve Hanley, Clean Technica, 12 June 2017
Building officials in Portland, Oregon, have approved the construction of what will be the tallest wooden building in the US. Known as Framework, the building will be 11 stories tall and provide subsidized living spaces on the upper floors while serving as home to Albina Community Bank and Beneficial State Bank on the street level, Digital Trends reports.
Michael Green is an architect in Vancouver who has pushed the idea of using wood to build tall buildings for decades. He says wood has many advantages. To begin with, it has a much lower carbon footprint than steel or concrete. Production of cement accounts for 5% of all global carbon emissions.
Australian architect Alex de Rijke says, “The 18th century was about brick, the 19th about steel, the 20th about concrete, and the 21st century is about wood.” Michael Green adds, “The Earth grows our food. The earth can grow our homes. It’s an ethical change that we have to go through.”
Green says a wooden building can have a carbon footprint 75% lower than a comparable steel or concrete building. He claims attitudes are the biggest hurdle he faces when talking to people — especially building officials — about using wood to construct large buildings. “I often say the hardest part of the job isn’t the engineering, it’s the managing of public perceptions of the issues, and it’s education.”
Modern wooden buildings are made using cross-laminated technology. High-tech polyurethane adhesives join sustainably grown lumber together at right angles into panels that can be up to 54 feet long and 10 feet wide. Depending on the needs of a particular building, they can be fashioned with anywhere from 4 to 7 layers of wood. They are crafted offsite and transported to the job site with spaces for windows and doors precut.
The panels are almost as strong as steel, retain their static strength and shape indefinitely and allow the transfer of loads on all sides. Construction time and waste at the job site are both reduced significantly compared to traditional building techniques. Testing of CLT products by Portland State University and Oregon State University has confirmed the panels can withstand large-scale earthquakes.
Logging in the Pacific Northwest has declined in recent years. The state of Oregon hopes CLT technology will help bring back some of the jobs that have been lost and has awarded a grant of $150,000 to D.R. Johnson Lumber to install production equipment that will be used to make the panels for the Framework building.
Other tall CLT buildings, which are often called “plyscrapers,” have gone up recently around the world. Michael Green has completed a 6 story CLT building known as the Wood Innovation Design Center in Prince George, British Columbia.
Vienna will soon be home to the tallest wooden building in the world at 276 feet in height. Project developer Caroline Palfy says wood is a perfect construction material for building. “It was used 200 years ago. It was perfect then and is perfect now.”