Architects are usually focused on the beginning of buildings, paying little attention to their end. But as climate impacts worsen, it’s a reckoning they’ll need to face: the four million tonnes of construction waste that Canada landfills annually comprises 40% of its total landfill content. That material leaches chemicals and releases CO2—and a lot of it could have been recycled, lessening the demand for new materials.
Adam Corneil, a Vancouver area certified Passive House Builder, saw this waste up close: he was constantly witnessing older buildings being torn down to make way for new ones. “I saw a lot of value in the old lumber that built our cities, which was being landfilled,” he says.
So he started Unbuilders. Instead of demolishing homes, his crews meticulously deconstruct them. Materials such as drywall, concrete, and asphalt shingles are recycled, while reusable hardware and fixtures are donated to Habitat for Humanity. Structural wood in good condition—which in older West Coast buildings is often tight-grained, highly valuable old-growth lumber—is appraised by an outside party and purchased by Unbuilders’ sister company, Heritage Lumber, for repurpose and resale.
The process is more time-consuming than a regular demolition, says Corneil, but the building owner recoups much of the cost difference—either through a donation receipt from Habitat for Humanity, or through a payment credit for the recouped lumber.
The business model works in part because of Vancouver’s Green Demolition bylaw, which requires companies to recycle three quarters of materials from homes built before 1950. This means that demolition companies are already stripping out the entirely recyclable drywall and plaster from buildings, leaving a bare structure. Unbuilders salvages that structure, instead of taking the more expedient approach of chipping it for use as fuel, landscape mulch, or in paper—uses that eventually release the carbon stored in the wood.
The company has scaled up quickly since it was founded four years ago. Unbuilders came away from Dragon’s Den with a $600K investment, and this year, its crews are planning take-downs of over 50 houses and a half-dozen commercial buildings. Corneil says that overall, his approach achieves 90 to 95% waste diversion.
Still, he’d like to see Unbuilders do more. He’s planning to expand to other cities in the eco-conscious Pacific Northwest, where several cities already require the diversion of construction waste. Then, onwards to the east. “It’s inevitable that deconstruction is going to replace demolition in the next 10 years,” says Corneil.
He’s also exploring ways to further upcycle wood from de-constructed homes: from creating wide-plank flooring to engineered wood products like reclaimed plywood, and even OSB from salvaged wood scraps. While wood is an eco-friendly building material, reclaimed wood has even less embodied carbon, beating new lumber by a factor of 12, says Corneil.
Architects also need to be thinking about adapting their work for the circular economy. Corneil notes how older buildings used high-quality wood and nails that allow for relatively easy de-construction, while since the 1990s, construction has relied more heavily on glues, screws, and adhesives. “That’s problematic, because we’re ensuring that at the end of the building’s life, it has to be landfilled,” he says. “How can you build to the degree of detail that you want, but so that it came come apart? It’s a great challenge for architects.”