As the new breed of six-storey pre-engineered wood buildings rises in Canada, critics are slamming the product, making “all sorts of claims” to stifle the new sector’s growth, says one industry expert.
Don’t take those claims seriously, says Lloyd Alter, an architect and editor, who gave a seminar at the Toronto Wood Solutions Fair titled How To Respond To All The Silly Things People (and other industries) Say About Wood Construction.
Alter, an adjunct professor at Ryerson University’s School of Interior Design, exposed what he says are some of the myths about wood that are mostly coming from its chief competitors, the steel and concrete industries.
He blasts the charge that a surge in wood buildings will contribute to deforestation, noting that harvesting wood for buildings in Canada takes "a small proportion of the forests" even when compared to forest fires and deforestation through pine beetle and other insect infestations.
He says that pine-beetle-infested forests, which were once considered useless, can be harvested for use in laminated timber products.
Furthermore, almost all of the harvesting of forests for engineered wood products is sustainable, Alter told an audience of architects, designers and builders at the seminar, which was one of several at the symposium presented by Ontario Wood WORKS!, a program of the Canadian Wood Council.
He says cutting fewer trees than the one-billion cubic metres of wood grown annually, according to statistics, keeps "things in balance" and still provides enough engineered wood to build the equivalent of 150,000 offices.
Alter pokes holes in the concrete industry’s argument that wood doesn’t have the strength or durability for construction applications in major buildings.
Just look to centuries-old timber frame structures still standing strong, he argues, pointing to medieval timber frame structures in Italy that continue to support masonry structures as a case in point.
Concrete proponents, he says, falsely compare modern concrete to that used by the Romans more than 2,000 years ago.
"Roman concrete is a very different product with a low carbon footprint. It is made from volcanic ash… and is in fact nothing like the concrete they use today," he states.
While masonry proponents suggest wood is a fire hazard, Alter argues that studies show heavy timber, including structural engineered wood such as cross-laminated timber, "does not burn that well."
"It has a char layer that protects the inner wood so if you design the wood for the dimension it needs after it burns then it is still just as strong," he says.
He says a British-based company has developed a fire-retardant treatment specified for wood during the construction phase prior to the installation of fire-protective measures such as sprinkler systems and fire-retardant wall and ceiling systems.
Alter refutes claims that engineered wood such as cross-laminated timber outgases as a result of the glues binding the product.
Alter points to an alternative: nail-laminated timber, a wood-strengthening method employed a century ago and still accepted in a number of applications under today’s building codes. Laminated wood held together with wood dowels is another alternative.
Contrary to what some people believe, he says wood is often favourable to concrete and steel in high-density neighbourhoods and infill projects partly because it is "quiet, clean and quick" to build with fewer trades.
It is also lighter than concrete and therefore requires less complex foundation systems. That can be an important benefit at infill sites adjacent to old buildings with foundations that might require underpinning, he says.
While towering wood buildings coined "plyscrapers" (up to 80 storeys) have been proposed in some countries, Alter says the jury is still out on such applications.
But for lowrise and midrise buildings wood has proven itself, he told the seminar.
"Every question the public asks about wood… we have answers to," he says.
"Wood can last as long as any concrete building if it is properly designed and properly maintained."