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Renderings of Arbora in Griffintown, Montreal, the world's largest residential project using a mass-timber structure.Sotramont

Montreal’s trendy Griffintown neighbourhood has experienced a flurry of new condominium construction over the past few years.

Amid all those developments there is a new kid on the block: the eight-storey Arbora condominium-apartment complex. While on the outside appearing not much different from its neighbours, Arbora on closer inspection turns out to be quite special. The three buildings making up the complex are built with wood skeletons instead of the standard steel or concrete.

Arbora’s promoters say the 366,000-square-foot development – made of cross-laminated timber (CLT) and clad in brick, steel-aluminum and fibre-cement – is the world’s largest residential project using a mass-timber structure.

It’s just the latest iteration in the increasingly popular use – at least in North America (Europe is well ahead of us in this department) – of wood as an eco-friendly, resilient replacement for the ubiquitous steel and concrete in constructing large buildings.

Canada can now also boast that it is home to the world’s tallest wooden tower: Brock Commons, an 18-storey student residence on the University of British Columbia campus in Vancouver.

Many other institutional, commercial and residential projects using wood are sprouting up across the United States and Canada.

One of the developers of Arbora said its construction was ’a lot of work.’Sotramont

Developers, engineers, designers and architects who are flocking to wood say it not only contributes to a major reduction in the carbon footprint, but also makes for a highly fire-resistant, light-but-sturdy and easy-to-install structural material.

The novelty and new construction techniques that come with it, however, can result in a set of challenges all their own.

“The innovation involved in construction brought about a certain level of complexity,” said Marc-André Roy, president of Montreal-based developer Sotramont, one of four partners behind Arbora.

“I’m proud of [Arbora] but it was a lot, a lot, a lot of work,” he said.

Case in point: The effort involved dealing with suppliers who were not 100-per-cent up to speed on CLT’s characteristics. Manufacturers of a special sealant to cover the holes in the CLT panels for cables to pass through had a bit of a learning curve at first trying to come up with the best solution for an effective product, Mr. Roy said.

And firemen from all over the city were keen on finding out more about CLT’s properties and knowing why it should not be viewed as the fire-safety hazard they imagined, Mr. Roy said.

Even the insurance people considered it prudent to send over their engineering inspectors for some up-close, on-site risk assessment, he said.

In the end, everyone was reassured and even – in many cases – impressed, Mr. Roy said. “The firemen who came to us at first with skepticism and lots of questions ended up being quite taken with the product.”

CLT is an engineered wood product – also known as mass timber – made of several layers of lumber that are stacked one on top of the other, each oriented at right angles to one another and bonded together under intense pressure using a non-toxic, environmentally friendly adhesive.

CLT is often sourced from sustainably managed forests; much of it comes from black spruce.

Proponents of wood-based construction say the manufacturing process for engineered wood consumes far less energy than steel and concrete.Sotramont

A key factor in its desirability as an ecologically smart product is the fact that it sequesters rather than emits carbon dioxide. Proponents say engineered wood products also consume far less energy in the manufacturing process than do steel and concrete.

They are also lighter, with potential savings in a building’s foundation costs.

And they allow for a high degree of prefabrication, also potentially lowering costs. Arbora’s supplier – Quebec-based Nordic Structures – shipped the components to the site from its plant in Chibougamau, Que in the form of prefabricated wood cut to the required dimensions, with openings for doors and windows, using computerized numerical control precision machinery.

“It’s like snapping Lego blocks into place,” said André Huot, head of business development at Nordic.

Nordic spokesman Frédéric Verreault says a Nordic-led project that was completed last year – the 13-storey Origine residential wood tower near Quebec City – was a big plus in helping spread the good word about how safe and reliable mass timber can be. “It proved to be very useful right at the moment when we started work on Arbora,” he said.

Rigorous fire-safety demonstrations over the past few years have convincingly shown that a CLT building would meet and even surpass code-compliance standards, he said, citing a 2014 test at the National Research Council’s large-scale fire-test facility in Mississippi Mills, Ont. A high-intensity blaze was set in a mock-up apartment next door to a full-scale three-storey stair/elevator shaft made of CLT. There were no temperature or smoke-density increases and no smoke leaked into the shaft, according to reports of the test sponsored by Quebec’s ministry of forests.

CLT has also passed other tests with flying colours; for example, when exposed to fire even for extended periods of time, the outer layer of a CLT beam or post chars and forms a kind of protective layer around the core, allowing it to retain its load-bearing capacity.

Amenities at Arbora include a swimming pool.Sotramont

The 435-unit Arbora complex – located, appropriately enough, on the site of a former lumber yard – is going up in three phases, said Annie Lemieux, president of real estate developer LSR GesDev, one of the partners in the Griffintown project.

As construction got underway, interest in the venture grew, she said.

“There was a lot of external interest from people who wanted to see the techniques used and the product. It really radiated outwards.”

Arbora’s other two partners are Aldo Bensadoun, founder of Montreal-based footwear retail giant Aldo Group Inc. and Toronto-based real estate investment firm Carttera.

The promoters say LEED Platinum certification is pending.

The units in Arbora have exposed wood posts and beams.Sotramont

Arbora’s condos, townhouses and apartments have exposed wood posts and beams, adding a touch of warmth to the interior design.

The complex includes retail space on the ground floor of one of the three buildings. Among the amenities are a community wine cellar, outdoor swimming pool, gym with a sauna, a space for bike repair and maintenance, electric-vehicle charging stations, bicycle parking and access to carsharing.

Mr. Roy says Arbora is an excellent fit for the hip, eco-sensitive Griffintown neighbourhood, squeezed in between Lachine Canal and the downtown; the former working-class Irish enclave is now home not only to dozens of condo projects but also art galleries, boutiques, brew pubs and restaurants. “In Griffintown, people are more open to innovation,” Mr. Roy said.