Wooden Skyscrapers

April 23, 2014

By Tim Richey

A couple of years ago, I shared lunch with Hans-Erik Blomgren, friend and structural engineer with Arup. We discussed the use of wood in tall buildings-specifically, the yet unexplored potential of Mass Timber construction and Cross Laminated Timber assemblies. Although CLT technology was developed in Europe in the mid-1990s, there were few examples in North America. At the time, Hans-Erik was in the early stages of researching the topic and developing a presentation that would introduce Mass Timber construction to Seattle architects and city code officials, and SRG served as a test audience while his research was still in-progress.

Last week, on April 16th, I attended a seminar hosted by WoodWorks (a non-profit initiative of the North American Wood Products Council) on Mass Timber and CLT construction. I was excited and inspired to see many new examples of innovative wood structures in Canada and Europe. However, despite an equivalent timber industry to western Canada, Mass Timber has been slow to catch on in the US.

In October of 2013, SRG's Emily Dawson blogged on the proposed use of CLT panels at the Oregon Zoo Visitor Hub. Using CLT in this application meant, as Emily notes, "We could cantilever the roof deck in two directions, which eliminated the need for clunky eave outriggers and provided a very clean, continuous plane of luminous wood...." This is a creative use of the technology, but Mass Timber construction has the potential to achieve so much more. In Austria, there is an eight-story Mass Timber office building, in London, a nine-story Mass Timber housing tower, and a 10-story multi-family building in Australia. Research suggests a 30-story wood structure is feasible. Is the Pacific Northwest ready for a wood highrise? At the moment, CLT construction is accepted by the City of Seattle, but to a maximum of six stories using Type 4 construction. WoodWorks continues to test their products and work with the local building departments to gain approval for taller structures. The 2015 IBC will recognize CLT for use in exterior walls.

Among the many of benefits of using wood in tall buildings, the one marketed most heavily is the lighter carbon footprint and the reduction in embodied energy when compared to concrete or steel construction. CLT construction can be 75% lighter than concrete, meaning smaller foundation loads and a better performing structure in a seismic event. Also, with much of the wood structural members and load-bearing panels engineered and fabricated off-site, there is a speed and efficiency benefit that can be achieved through wood construction.

There are many hurdles to clear before we see a wood high-rise in this region—notably, building code changes, fire safety approvals, and an understanding of the cost benefits. As Mass Timber construction gains visibility, and code changes begin to recognize these materials and methods, all that's missing is a visionary client and an architect who can guide them there.

The USDA and White House Rural Council in Washington, DC recently announced $1 million in funding for WoodWorks and $1 million to fund a tall wood building competition. The initiative is intended to "accelerate technology transfer and implementation of expanded uses of wood products for building construction." Ethan Martin, Technical Director at WoodWorks, says the competition brief will likely to be released in the fall. Perhaps this is a competition we keep in our sights?

Additional Resources

  • Earth Sciences Building, University of British Columbia - A 5-story lab and classroom building wood columns and CLT panelized construction.
  • LifeCycle One building in Austria - an aluminum-clad 8-story tower utilizing prefabricated wood columns, wood walls, and a wood-concrete hybrid slab.
  • Stadthaus, 24 Murray Grove, London - An 8-story residential tower constructed entirely in wood above a single-story concrete podium. Currently the tallest timber residential building in the world.
  • AIA Continuing Education - Tall Wood Takes a Stand
  • The Case For Tall Wood Buildings: How Mass Timber offers a safe, economical, and environmentally friendly alternative for tall building structures. Perpared By, mgb ARCHITECTURE + DESIGN

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Tim Richey

AIA, LEED AP

Senior Associate