After demolition, building materials get a second life

The red brick began its life as clay in the bottom of the Don Valley. In 1913 it was fired, shaped and shipped across downtown Toronto to form a wall at the city’s abattoir. Now that abattoir, near Bathurst and King streets, has been reduced to rubble. The brick sits, with many others like it, in the winter sun waiting for its next chapter as part of a remade neighbourhood.

Five new buildings will go up at the site of the old abattoir, totalling a million square feet of apartments, shops and offices. As they do, the brick and other materials from the destroyed building will take on new forms. The brick itself will go into a new retaining wall, where it will remain visible within a steel mesh, explained Marc Ryan, a landscape architect and principal of the firm PUBLIC WORK. Nearby, sections of steel chimney flue stand ready to become planters. And an excavator is dicing up concrete from a building foundation that will also become part of a retaining wall.

“Every material has a story,” Mr. Ryan said. “Here, we imagine a second life for these materials that could contribute to the experience and the texture of the place.”

Open this photo in gallery:

That redevelopment offers an example of what’s known as “deconstruction,” the intentional reuse of building materials when a structure is being taken down. In general, demolition of a building creates huge amounts of garbage; construction and demolition generate about a quarter of all Canada’s solid waste. But through initiatives such as this, materials can be reused – generating both environmental benefits and more interesting places.

Deconstruction “is building in reverse,” explains Alison Creba, an expert on material reuse who leads the think tank Local Technique. “It means taking architectural components so they can be reused – either as the joist or slab that they are, or repurposed.”

This practice combines environmental and aesthetic motivations. And that kind of thrift, a century ago, was normal. Buildings were wrecked largely by hand with small tools; doors, windows, fixtures and panels of wood or stone could all be removed and resold. But larger machinery and changing techniques changed the business, says Ms. Creba. Careful sorting of waste was viewed as unnecessary.

In the past generation, the pendulum has swung back. Waste disposal is expensive, and demolition contractors can increasingly find financial value in materials. Steel and other metals can be easily recycled. Concrete can be broken down into a gravel-like substance and reused, with some limitations, in new concrete.

Open this photo in gallery:

Priestly Demolition, the Ontario-based firm working on the abattoir project, now typically recycles 80 per cent of the materials on a site, spokesperson Connie Clearwater says. It operates a salvage yard, too; the company was featured on the cable TV show Salvage Wars.

But not all reuse strategies are equally beneficial. Operations such as concrete recycling consume energy, and leave behind significant waste. “Often, demolition includes a crushing of materials,” explains Ms. Creba. “That means materials are contaminated: buildings are full of adhesives and foams. A lot is lost in the process.” And even in such processes as concrete recycling, she adds, materials become less valuable.

The better and more complicated alternative is to retain materials in their original form, ideally for their original purpose. This is part of what’s known as a circular economy. Such practices are growing in Europe, and now in Canada, thanks to environmental regulation on carbon emissions and waste. Victoria and Vancouver both have bylaws in place that require wood from older houses to be recovered for reuse. This has helped create a small sector of specialized deconstruction firms in British Columbia.

For the developers of the Toronto project, TAS, material reuse is part of a low-carbon strategy. The new mixed-use buildings at 2 Tecumseth Street will include roughly one million square feet of floor space. Their construction will consume significant resources and generate carbon emissions. But the plan to reuse materials in the landscape will retain 6000 tonnes of material, explains the company’s net-zero co-ordinator Robert Raynor. That reduces the complex’s environmental impacts in two ways. “We’re saving old materials from being trucked to landfill,” Mr. Raynor explains, “and we’re also preventing new materials from being created from scratch.”

TAS’s analysis suggests that 990 tonnes of emissions will be avoided through the reuse of materials. This accounts for “embodied energy” – the energy and carbon dioxide emissions that were already created during the making of the building components and the original construction of the building.

This environmental benefit is matched by a cultural one. Some advocates, including Ms. Creba, see material reuse as an extension of heritage preservation. If an entire building is not being reused, then some of its components can keep its memory alive. “Seeing something reused tempers the loss of that place being removed from where it is in the world,” she said.

Open this photo in gallery:

Mr. Ryan, the landscape architect, echoed that idea. Walking through the demolition site, he pointed to a stack of patterned concrete slabs. “It’s not just concrete,” he said. “It’s the floor of an animal shed, where the hooves of livestock found their grip.” On the abattoir site, “the theme of life, death and rebirth is very strong,” he added.

That red brick, once integral to the abattoir, will remain in the retaining wall as a reminder of what once was. Slabs of concrete will be set irregularly into new pathways, providing a solid surface and a visual texture. Salvaged old-growth timber will be transformed into benches and stools.

New apartment buildings will rise here, and gardens will grow over chunks of rubble. “There are good reasons for doing this,” Mr. Ryan said. “It’s the right thing to do. But also, sometimes the new is a bit soulless. Here, the past will still be present.”