Building Life Cycle: Demolition Recycling
Last week, we looked at how construction teams can reduce their environmental footprint by using good construction waste management practices. In the second part of this two-part blog post, we’ll look into what happens when a building has outlived its usefulness, and must come down in order to make room for a new structure or land use. Demolition recycling is an important step in a building's life cycle, as material reclamation and good recycling practices can divert over 90% of the building's material from the landfill.
Part 2: Demolition and Deconstruction
The largest components of demolition waste are concrete, metal, and wood. These materials are typically found in the structural elements of buildings and represent the majority, by weight, of materials left over from demolition. Fortunately, each of these materials are highly recyclable: concrete can be crushed and used in road base or fill, often on-site, metal can be quite valuable and can be sold to metal recyclers across the country, and wood waste can be ground up into mulch and used either as biomass to produce electricity, or composted in commercial compost piles. Removal of these materials, however can be time consuming.
Due to layers of finish materials (insulation, drywall, etc.) that typically hide the structure from view, structural materials require time and labor to extract. Traditional demolition bypasses much of this labor by tearing down the building with wrecking equipment. This method is fast and relatively inexpensive, but the damage to building materials is such that some cannot be recovered, and those that can be are contaminated with other materials.
Construction and demolition waste recycling is on the rise, with new C&D recycling infrastructure being built across the country. As more contractors and property developers are concerned with the environmental impact of their jobs, and state and local regulations enact demolition waste diversion minimums, a new alternative to traditional demolition has appeared in the industry: deconstruction.
Don’t tear it down, Take it apart
Deconstruction is a new term for a simple concept: rather than destroying or demolishing a building, crews carefully disassemble the structure, salvaging valuable materials for reuse. In addition to reducing the cost of disposing of demolition waste in landfills, deconstruction allows project teams to reuse, resell, or donate valuable material for tax benefits, reducing the overall cost of the job.
Removing reusable, non-structural elements from the building is known as a “soft-strip” and focuses on salvaging materials such as lighting and plumbing fixtures, interior finishing items, cabinets, counters, mechanical equipment and any other materials that can be reused. The soft-strip is important for recovering items that will be damaged during the structural takedown and which can only be recycled while in good condition.
After a building has been soft-stripped, crews work to break down the structure of the building as much as possible without heavy demolition equipment. While larger commercial buildings and multifamiily housing often have steel and concrete structures that must be taken down with excavators, wood-frame buildings can often be completely deconstructed, down to reusable studs and framing timbers.
Finding a qualified deconstruction contractor to work with you on your project will make the process smooth and effective. The Building Materials Reuse Association keeps a searchable directory of contractors online, as well as a map of deconstruction resources.
Get Out What You Put In
The selection of materials to be reused after a building has come down does not need to begin at the time of deconstruction. Increasingly, architects are using the principle of “design for deconstruction”: taking the building’s end-of-life potential for reuse into account during the design phase.
Best practices to design for deconstruction include:
Use of removable bolts instead of nails or adhesives
Easily accessible mechanical equipment and structural components
Choosing durable, high-quality materials that will retain value over time
Choosing materials with high recyclability
When done right, design for deconstruction will ease the task of deconstructing a building, making the process simpler, less expensive, and more successful, as a greater percentage of materials can be reclaimed, and those materials are likely to be of higher quality.
When we think about sustainability, it is important to look holistically at the entire life-cycle of our buildings, from first concept to material salvage. By thoughtfully designing new buildings to be long-lasting and easy to deconstruct, architects can help to close the loop on building material use, reducing the amount of virgin materials that need to be extracted, and limiting the amount of valuable material that is thrown away after a building comes down.