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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.
Additional recommended knowledge
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 due to the fact that construction and demolition (C&D) waste accounts for approximately 20% of the solid waste stream.
Typical methods of deconstruction
Deconstruction is commonly separated into two categories; structural and non-structural. Non-structural deconstruction, also known as “soft-stripping”, consists of reclaiming non-structural components appliances, doors, windows, and finish materials. The reuse of these types of materials is commonplace and considered to be a mature market in many locales.
Structural deconstruction on the other hand involves dismantling the structural components of a building. Traditionally this had only been performed to reclaim expensive or rare materials such as used brick, dimension stone, and extinct wood. In antiquity, it was common to raze stone buildings and reuse the stone; it was also common to steal stones from a building that was not being totally demolished: this is the literal meaning of the word dilapidated. Used brick and dimension limestone in particular has a long tradition of reuse due to their durability and color changes over time. Recently, the rise of environmental awareness and sustainable building has made a much wider range of materials worthy of structural deconstruction. Low-end, commonplace materials such as dimensional lumber have become part of this newly emerging market.
The United States military has utilized structural deconstruction in many of its bases. The construction methods of barracks, among other base structures, are usually relatively simple. They typically contained large amounts of lumber and used minimal adhesives and finish-work. In addition, the buildings are often identical, making the process of deconstructing multiple buildings much easier. Many barracks were built during the era prior to WWII, and have aged to the point where they now need to be torn down. Deconstruction was deemed very practical due to the abundance of labor the military has access to and the value of the materials themselves.
Natural disasters, such as hurricanes, floods, tsunamis, and earthquakes often leave a vast amount of usable building materials in their wake. Structures that remain standing are often deconstructed to provide materials for rebuilding the region.
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.
Reclaiming the materials for a new on-site structure is the most economically and environmentally efficient option. Tipping fees and the costs of new materials are avoided; in addition, the transportation of the materials is non-existent. Selling the used materials or donating them to non-profit organizations are another effective way of gaining capital. Donations to NPO’s such as Habitat for Humanity’s ReStore are tax deductible. Many times it is possible to claim the value to be half of what that particular material would cost new. When donating rare or antique components it is sometimes possible to claim a higher value than a comparable, brand-new material.
Value can also be added to new structures that are built by implementing reused materials. The U.S. Green Building Council's program entitled Leadership in Energy and Environmental Design (LEED) offer seven credits relate to reusing materials. (This accounts for seven out of a maximum sixty-nine credits) These include credits for building-shell reuse, material reuse, and diverting waste from landfills. Building shell-reuse is particularly appropriate for shells made of dimension stone.
When choosing to deconstruct a building there are some important aspects that need to be taken into consideration. Developing a list of local contacts that are able to take used materials is an essential first step. These might include commercial architectural salvage businesses, reclamation yards, not-for-profit and social enterprise salvage warehouses, and dismantling contractors. Materials that cannot be salvaged may be recycled on-site or off-site, or taken to landfill. The next step involves identifying which, if any, are hazardous materials. Lead paint and asbestos are two substances in particular that need to be handled extremely cautiously and disposed of properly.
It is common practice, and common sense, to “soft-strip” the structure first; remove all appliances, windows, doors, and other finishing materials. These will account for a large percentage of the easily sellable components. After the non-structural deconstruction, structural is the next step. It is best to start at the roof and work down to the foundation.
Building components that are dismantled will need to be stored in a secure, dry location. This will protect them from water damage and theft. Once separated from the structure, materials can also be cleaned and/or refinished to increase value. Building an inventory list of the materials at hand will help determine where each item will be sent.
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.
An alternative worth considering is modular building, like the Habitat 67 project in Montreal, Canada. This was a residential structure consisting of separate, functional apartments that could be put together in a variety of ways. As people moved in or out, the units could be reconfigured as desired.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Deconstruction_(building)". A list of authors is available in Wikipedia.|