Deconstruction of buildings

By Jonathon Harp

Old apartment buildings being to be demolished.

The approach of dismantling buildings has a lengthy history and has reappeared as part of the move towards environmentally sustainable buildings. Its more recent iteration is referred to as deconstruction.

Build Reuse, a U.S. non-profit with a mission to foster the recovery, reuse and recycling of building materials, describes deconstruction of buildings as “the process of dismantling a structure to maximize the recovery of reusable material. Sometimes called “construction in reverse” or “unbuilding,” deconstruction removes a building by selective disassembly of structural and non-structural building components. This stands in contrast to conventional demolition, which uses mechanical equipment like bulldozers and wrecking balls, resulting in limited reusability.”

As opposed to demolishing buildings, which results in large amounts of waste ending up in landfill, deconstruction allows for the reuse of portions of buildings or their component parts. It has been discovered in the deconstruction process that building components in many cases are valuable for reuse in new or renovated buildings thus sustainably eliminating the need for new components and reducing waste.

The deconstruction process is normally divided into two types; structural parts of the building such as bricks, support beams and wood, and non-structural parts such as windows, doors, equipment, and other components.

Sustainability

According to the federal government as of April 2021, “Construction, renovation and demolition waste represents a significant portion (4 million tonnes or 12 per cent) of the solid waste stream generated in Canada.” Deconstruction sustainably provides reused building materials with a “new life cycle” and decreases the need for new materials, which in turn decreases the need for energy and reduces GHG emissions.

Deconstruction also occurs at the local level, which creates additional emission reductions from the transportation of materials, as well as removing traditional demolition solid waste from landfill. According to some experts, 90 per cent of construction waste is created by the demolition process.

Job creation

Deconstruction is a tool for underemployed sectors.

Being a locally-focused endeavour, deconstruction has proved to be a source of employment opportunities for local communities and is a “tool for workforce development” particularly in the underemployed sectors. According to Delta Institute, “Deconstruction creates 6-8 jobs, for every job created by traditional demolition.” The work is labour intensive and needs teams of workers who understand the deconstruction process. As an example, demolition of a 300 sq. metre home needs two to three workers where deconstruction needs six to eight workers.

This new sector also needs “a substantially higher degree of hands-on labour than does traditional demolition.” This opens the door for unemployed and unskilled people in the community to obtain deconstruction training and re-enter the workforce. Deconstruction also has a positive effect on the reuse business and supports jobs in warehousing,

Designing buildings for deconstruction: How does this effect the mechanical industry?

Another aspect of deconstruction making some headway is the idea of designing buildings from the start with aspects that support deconstruction at their end of life. This process has been given the name “designing for deconstruction (DFD).” It is gaining some traction in the design field as part of sustainable architecture.

Reclaimed wood.

The deconstruction architectural approach is to use “simple construction methods” and put them together with “high grade, durable materials.” Other things to consider are making the building’s core more visible and components easier to separate so they can be taken apart. The use of accessible bolts as fasteners also lead to simpler deconstruction as well as grouping mechanical systems together within the building to reduce service lines from being too lengthy and becoming intertwined with other parts.

Other design features supporting deconstruction include raised floors and drop ceilings that allow easy access to mechanical, electrical and other building components. There are a number of standard construction approaches that do not foster deconstruction and make some materials unusable, including fasteners such as glue and nails.

The DFD design approach provides other benefits beyond easy deconstruction at a building’s end-of-life. These buildings are typically “easier to maintain and adapt to new uses,” which reduces their environmental impact.

Deconstruction in Canada

The deconstruction business in Canada is just getting started. There are some companies that specialize in deconstruction of buildings and demolition companies are looking at deconstruction methods to enhance their services. This practice was a “thrifty” approach to taking down buildings a century ago. It was normal practice to bring down buildings by hand, which provided access to structural and non-structural components for reuse.

Reclaimed windows.

However, changes in machinery and techniques moved away from reusing building materials around the mid-20th century. The pendulum swung back in the latter portion of the century and into the 21st century as the cost of waste disposal and sustainability of buildings came to the forefront of building construction.

The “old” practice of reusing components from end-of-life buildings is being resurrected and gaining traction in Canada. The current deconstruction approach recognizes that some reuse does not meet sustainability standards; for example, the energy use and waste generated by concrete recycling. The better approach is to leave materials in their original form and use them for their original purpose. This is called the circular economy, which is expanding worldwide as regulations are put in place to reduce waste and carbon emissions.

As Dr. Hannah Teicher of the Pacific Institute for Climate Solutions in B.C. noted in a recent article on deconstruction, “embodied carbon advocates tend to focus on improving building materials for new construction. Deconstruction could offer an important pathway [to reducing emissions] by funnelling overlooked resources to their highest and best use.”

BC is a good example of how the deconstruction approach is making headway. Both Victoria and Vancouver have bylaws in place that require wood from end-of-life homes to be recovered for reuse. TAS, a Canadian company involved in the deconstruction business, estimates that reusing construction materials will eliminate 990 tonnes of future GHG emissions.

Deconstruction is an environmental alternative to simple demolition of buildings. For example, instead of simply relying on the shrinking supply of wood from Canadian forests for new homes and buildings, the construction industry needs to increase the use of materials that are already in use. Reused old growth timber can be used in construction for a wide variety of wooden building parts.

 

 

 

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