Vancouver-based architect Michael Green was unequivocal at a conference at which I heard him speak a while ago: "We grow trees in British Columbia that are 35 stories tall, so why do our building codes restrict timber buildings to only five stories?"
True, regulations in that part of Canada have changed relatively recently to permit an additional story, but the point still stands. This can hardly be said to keep pace with the new manufacturing technologies and developments in engineered wood products that are causing architects and engineers to think very differently about the opportunities wood offers in the structure and construction of tall buildings.
Green himself produced a book in 2012 called Tall Wood, which explored in detail the design of 20-story commercial buildings using engineered timber products throughout. Since then he has completed the Wood Innovation and Design Center at the University of North British Columbia which, at 29.25 meters (effectively eight stories), is currently lauded as the tallest modern timber building in North America.
How Timber Grew Tall
Until recently, the potential for using timber in towers was very limited. Platform timber frame – the system used, for example, to construct more than 70% of Scotland's housing, by my calculations – is effective up to seven stories in height. In Scotland, we build four or five stories in timber as a matter of course. But any higher than seven stories and structural challenges and simple economics always made it less effective.