Architects at SOM are working on the Timber Tower, a 42-story building that is made entirely out of cross-laminated timber for the floors and laminated timber for the columns, reports Chicago Magazine's Whet Moser.
Cross-laminated timber (CLT) has led to new options for building since it emerged in Austria in the 1990s. The process works like this: wood is laid together so that the grain of each layer is perpendicular to the grain of the next, glued, and pressed, making it more rigid than regular laminated timber, where the grains run parallel.
“Cross-laminated timber has been a building product really used in Europe for the past 20 years or so, for all types of different construction,” says Benton Johnson, the SOM associate who’s leading the firm’s Timber Tower project. “But in the United States, the material itself was being used primarily for temporary foundations, for construction access, things of that nature. It was used as more of a hard-working industrial product for a long time.”
SOM says the material allows for building to heights far beyond what is allowable by code, meaning the material is so strong it can support a building that’s very large.
The Timber Tower project passed its first major test recently: a 36-foot-by-8-foot floor section of CLT coated with reinforced concrete supported 82,000 pounds, exceeding required loads and structural expectations. Fire is an intuitive concern with a wood building, but CLT is more fire-resistant than you might intuit. It is wood, and it does burn, but it burns slowly and predictably, and while it burns, it creates an insulating layer, which protects from some of the structural dangers with fire.
Original link - Builder Online
