Timber back in vogue, but for high-rises

● More than a century after steel and concrete became the standard for building highrises, the humble tree is making a comeback. Sidewalk Labs, a unit of Google parent Alphabet, plans to use timber to construct all of its buildings for a mixed-use community along Toronto’s eastern waterfront.

Meanwhile, Oregon became the first US state to amend its building code to permit taller buildings made from timber, as high as 18 stories. The material can “contribute to people’s wellness, is beautiful, easy to assemble, and strong enough support to build dozens of storeys,” said Karim Khalifa, director of buildings innovation at Sidewalk Labs.

The push comes as timber becomes more cost competitive as steel prices rise, and the use of prefabricated wood panels allows for quicker construction.

As opposed to the heavy timber construction from 100 years ago, builders are using so-called mass timber from younger, smaller trees that are engineered together, said architect Michael Green, an early proponent of the material. Cross-laminated timber consists of layers of wood glued together to form solid, thick panels that can be made for anything from walls and floors to beams and roofs.

Tests have shown the timber has good levels of fire resistance — close to three hours in some cases — even when unprotected, says the National Research Council Canada.