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BOULDER, Colo. 鈥� Proponents of a growing movement in the construction industry are asking: Why tear down old buildings with wrecking balls when those materials can be mined for reusable materials?
The practice, called deconstruction, creates a circular economy of reuse for building materials. It keeps waste out of landfills and shrinks the carbon footprint of buildings and infrastructure. It's the kind of idea that sounds like an obvious win-win. But as the built environment rapidly changes over from one generation to the next, communities may not yet have the infrastructure 鈥� the sorting facilities and reuse stores 鈥� to keep up with new demand.
Deconstruction and reuse industries have taken flight in the past five to 10 years in cities like Portland, Ore., and Boulder, Colo., where much of the original aging housing stock is now being replaced to suit the tastes of a much wealthier 21st-century population. As old homes come down to make way for new ones, specialist contractors like Anna Perks are moving in to handle the materials left behind.
"Our team is systematically unbuilding the structure," said Perks, co-owner of Perks Deconstruction, a contracting company that disassembles buildings for parts. She was hired to make a snug three-bedroom, two-bath home near the top of a green, hilly street in Boulder disappear.
Her crew worked quickly. After the first day on-site, the roof of the house disappeared. The siding, too. A crew wielding hammers and crowbars pried pieces of wood sheathing off the studs and carefully sorted materials. Others clawed nails out of two-by-sixes in the backyard.
"We've got a pretty good pile of lumber," she said. "That's all ceiling joists and floor joists. There's a lot of good reusable lumber in there."
The workers were trained to work precisely and with patience to keep the lumber as intact as possible as they removed it from the house.
"Typically, what happens is a bulldozer will come in, smash it all 鈥� it'll all get trashed," Perks said. "But deconstruction, we try to salvage and recycle as much as possible."
The carbon emissions embodied in buildings
The idea is to limit the climate impact of our built environment, which accounts for of global greenhouse gas emissions. of that comes from the of construction materials, according to Michelle Lambert, the policy and engagement manager at the nonprofit Carbon Leadership Forum.
"Embodied carbon is the greenhouse gas emissions that are generated by the manufacturing, the transportation, the installation, all the way through to the disposal of construction materials that are used in buildings or in roads and other infrastructure projects," Lambert said.
For a long time, experts have focused on the of building operations 鈥� the energy used to heat, cool and electrify spaces.
"But in the last five, 10 years, we've really started to understand that the materials and the processes that have created those materials are a really significant piece of the whole carbon footprint of buildings as well," she said.
The big promise of deconstruction is in creating a for building materials: harvesting lumber, say, from an old house, rather than a forest.
"Making use of the materials that we have already manufactured is one of the most impactful ways that we can reduce embodied carbon," Lambert said. "Eliminating all of those emissions that would've been required to create new materials."
The challenges of deconstruction
Chris Fellows, president of Colorado-based development company Resolute Strategies, hired Perks Deconstruction to dismantle a few crumbling farm buildings on a former homestead he's now building out as a mixed-use residential neighborhood in Aurora. In his brief for the project, he included reusing as many of the original materials as possible on-site.
Bricks from the farmhouse and siding from the barn have been set aside in containers. They'll be incorporated into a new community center for the neighborhood.
"This was a place where there's cool history and culture in the pioneers and the settlers that came out and did ," Fellows said. "We're trying to honor that part of that culture and history of Colorado."
Fellows said he and his partners also liked deconstruction as a way to cut the carbon footprint of the project.
"We wanted to be good stewards of the land in terms of the climate and the environment," he said. "So, to the extent that we could reuse and recycle any materials, we wanted to do that, so we don't have to consume as much new material, nor do we have to take as much stuff to a landfill."
Just because the interest is there doesn't mean the execution is easy. A successful deconstruction program requires local infrastructure for processing and distributing salvaged materials, not to mention local end markets 鈥� people who want to buy and use those materials. Boulder, for instance, has a robust that includes expert contractors and recycling facilities for concrete, masonry and lumber, not to mention several building-materials reuse stores and donation centers.
But a lot of places don't have those resources.
"We have to have a place to take all this material," Perks said. "It gets really hard for contractors when there's nowhere to take the material."
The extra cost of deconstruction can also make it a hard sell. Homeowners and developers may be motivated by environmental reasons, but the economic incentives aren't there.
Fellows estimates that deconstruction increased project costs 35% to 40% and added at least a year to the schedule.
"Because we had to stage things carefully and do them in a certain sequence," he said. "And we had to find the right people."
Even so, Fellows said he's glad they went for it and even thinks he'll see an eventual return on the investment when eco-conscious homebuyers learn about the process.
"We'll have to check back in three to five years. We'll see if we think that's happening," he said. "But I think it was still the right thing to do."
On the books
A of local governments, from , to , and counting, now either require some percentage of demolition waste be salvaged, reused or recycled, or incentivize those practices. Portland, where has been on the books since 2016, was among the earliest deconstruction pioneers.
In Boulder, more than 140 million pounds of materials have been kept out of landfills since a was adopted in 2020, according to the city of Boulder's circular economy policy adviser, Emily Freeman.
"All residential and commercial buildings are required to be deconstructed," Freeman said. "The ordinance requirements are that 75% or more of those building materials are diverted from landfill."
So far, the city has overshot that goal. Over the last five years, Freeman said, more than 83% of the construction waste generated in Boulder has been kept out of landfills.
As the movement matures, Perks said, the next frontier in deconstruction would be to before a building ever got built.
"Can you either incorporate reclaimed materials into the new design, or when you're designing, can you think about what's this going to be like to take it down?" she said. "And when it gets taken down, can it be reused?"
Perks says the future of climate-conscious construction will be knowing exactly how you'll take a building apart before you even put it together.
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