The high-rises that make up our beautiful skyline are built primarily with steel and concrete. That’s the way it’s been for much of the twentieth century.
However, one of our oldest materials has experienced a renaissance in recent years: there’s a growing movement of using timber to build towers.
Why Wooden Skyscrapers?
- They are energy efficient.
- Faster construction timelines are possible (often half that of a concrete structure). That’s because large wood panels can be prefabricated off-site and quickly assembled and installed on-site.
- Wood emits less carbon dioxide compared to steel or concrete buildings.
- It’s lightweight — a wooden building is about a quarter of the weight of an equivalent reinforced concrete structure. It’s also quieter to build with.
Clearly, wood offers a number of benefits. So why hasn’t it caught on earlier? Two concerns have dominated the arguments in eschewing wood when building high — 1. Durability and 2. Combustibility.
Many have questioned whether wood is appropriate for tall structures. Recent advances in technology have overcome the durability question:
- The biggest is the development of a highly engineered material called cross-laminated timber (CLT).
- CLT is a wood panel made from three or more layers of lumber that are stacked at right angles and glued together. The floor slabs are almost as long as a bowling lane and can be as thick as 12 inches.
- It gives more rigidity and strength to wooden structures.
The second worry is combustibility. Skeptics think that wooden skyscrapers are fire hazards. History is filled with examples of cities ruined by fires, like the ones in London and Chicago in the 1800s that resulted in wood being banned from tall structures.
However, technology has changed. Previous fires were started from small pieces of wood. The combination of the composition and the thickness of these slabs prevent fire from spreading by charring when exposed to flame.
Vancouver’s Own Wooden Skyscraper
Vancouver is paving the way in using wood as a construction material. Led by Acton Ostry Architects, the Brock Commons dormitory at the University of British Columbia is one great example. Once it’s finished this year, it will house more than 400 students.
- At 18-storeys (174 feet tall), its poised to be one of the tallest contemporary buildings in the world that is made mostly of wood. It likely won’t hold that title for long though, since many more are in the works.
- It’s a hybrid structure, with a concrete core for sturdiness and drywall for protection against fire.
- The prefabricated nature of the project results in a quick construction time — a rate of one floor every three days.
- It’s estimated that Brock Commons saves the environment 2,432 metric tons of CO2, or the equivalent of taking 500 cars off the road for a year.
Prior to this, one of the tallest mass-timber buildings in the west was also in B.C., at the University of Northern British Columbia in Prince George. The Wood Innovation and Design Centre is six floors and designed by a major advocate of wood, Michael Green.
Many other countries have started to push the frontiers of using wood as a construction material. New buildings have started to sprout up in cities such as Norway, Australia and Amsterdam, just to name a few.
Vancouver has plans for more, too. Shigeru Ban’s first Canadian project in Coal Harbour has been given the green light. It’s called Terrace House, and its goal is to become one of the tallest timber skyscrapers in the world.
One of the reasons why we haven’t seen more interest in wooden skyscrapers is because of regulations. In B.C., for example, the building code allows the construction of wood buildings as high as six storeys. A site-specific regulation has to be established for each tall wood building.
More and more architects and engineers will need to persuade building departments to approve high-rises made of timber. The hope is that with the success of wood buildings like the UBC dormitory, people will start to accept that this traditional material is safe, sustainable and economically smart.
If you want more information on wooden skyscrapers, please don’t hesitate to get in touch with us!