Deconstruction vs Demolition

What is deconstruction?

In the context of physical construction, deconstruction is the selective dismantlement of building components, specifically for re-use, recycling, and waste management. It differs from demolition where a site is cleared of its building by the most expedient means. Deconstruction has also been defined as “construction in reverse”. The process of dismantling structures is an ancient activity that has been revived by the growing field of sustainable, green building. Buildings, like everything, have a life-cycle. Deconstruction focuses on giving the materials within a building a new life once the building as a whole can no longer continue.

When buildings reach the end of their useful life, they are typically demolished and hauled to landfills. Implosions or ‘wrecking-ball’ style demolition is relatively inexpensive and offers a quick method of clearing sites for new structures. On the other hand, this method creates substantial amounts of waste. Components within old buildings may still be valuable, sometimes more valuable than at the time the building was constructed. Deconstruction is a method of harvesting what is commonly considered “waste” and reclaiming it into useful building material.

Contribution to sustainability

Deconstruction has strong ties to environmental sustainability. In addition to giving materials a new life cycle, deconstructing buildings helps to lower the need for virgin resources. This in turn leads to energy and emissions reductions from the refining and manufacture of new materials. As deconstruction is often done on a local level, many times on-site, energy and emissions are also saved during the transportation of materials. Deconstruction can potentially support communities by providing local jobs and renovated structures. Deconstruction employs 3-6 workers for every one employed in a comparable demolition job. In addition, solid waste from conventional demolition is diverted from landfills. This is a major benefit because construction and demolition (C&D) waste accounts for approximately 20% of the solid waste stream.

Economic potential

Deconstruction’s economic viability varies from project to project. The amount of time and cost of labor are the main drawbacks. Harvesting materials from a structure can take weeks, where as demolition may be completed in roughly a day. However, some of the costs, if not all, can be recovered. Reusing the materials in a new on-site structure, selling reclaimed materials, donating materials for income tax write-offs, and avoiding landfill “tipping fees” are all ways in which the cost of deconstruction can be made comparable to demolition.

Designing for deconstruction (DfD)

An upstream approach to deconstruction can be implemented into buildings during their design process. This is a current trend in sustainable architecture. Often, simple construction methods combined with high-grade, durable materials work best for DfD structures. Separating layers of a building’s infrastructure and making them visible can significantly simplify its deconstruction. Making components within systems separable also assists in being able to dismantle materials quickly and efficiently. This can be achieved by using mechanical fasteners such as bolts to connect parts. Allowing physical access to the fasteners is another needed aspect of this design. Also, it is important to use standardized materials and assemble them in a consistent manner throughout the project.

Some conventional construction methods and materials are difficult or impossible to deconstruct and should be avoided. The use of nails and adhesives significantly slow down the deconstruction process and have a tendency to ruin good materials. Avoid hazardous materials altogether as they detrimental to the natural environment and are non-reusable. Using mixed material grades make the process of identifying pieces for resale difficult. Try to use similar grade woods and metals and identical length members throughout the structure.

Deconstruction is important for more than just the end of a building’s life-cycle. Buildings that have been designed with deconstruction in mind are often easier to maintain and adapt to new uses. Saving the shell of a building or adapting the interior space to meet new needs is the ultimate choice in terms of environmental sustainability. Flattening a salvageable building and building a similar one in its place is generally inadvisable.

Courtesy of Wikipedia