If you were to look in a dictionary for a definition of the word "deconstruction," it probably won't be found-not yet, anyway. It's one of those words that grew out of the English language as a composite term to describe what is essentially the process by which a building is disassembled in the reverse order by which it was constructed. Inherent in this process is the reuse of as much of the salvaged materials and components of the structure rather than recycling and/or discarding the structure's materials and components in a landfill as construction and demolition waste.
A penny saved ...There was a time, prior to World War II, when it was the norm for demolition contractors to dismantle a building in such a way as to salvage as many building components/materials as possible for reuse (they were even commonly referred to as dismantlers). Higher labor rates, increased mechanization, stringent worker safety and protection laws, as well as advances in building technology such as monolithic structural systems, and the use of composite materials and adhesives, makes extensive salvage impractical in the mind of the typical modern demolition contractor. They now prefer to recycle and/or dispose of C&D waste. At first, you might think that it's the cost of disassembly that makes demolition contractors balk at deconstruction. That's secondary. It's the time factor that is the primary cause of their concern/hesitation.
Demolition contractors and the emerging deconstruction industry have a tendency to stereotype one another though they have much in common. Traditional "demolitionists" see deconstruction as limited to the manual disassembly of "stick-built" (wood/timber frame) residential structures. In their view, without government subsidies, non-profit organizations and welfare-to-work training programs, deconstruction projects would not exist at all. To the "deconstructionist," demolition contractors are brutes applying brute force to simply bring a building down and bury the remains. To them, this is a waste of both social and environmental opportunities. Like most stereotypes, there is some truth and in both stereotypes.
Deconstruction-as a term of use-first came into existence in the mid-1990s, probably as a result of a meeting of the Used Building Materials Association (www.ubma.org). It emphasizes both the manual and mechanical disassembly and salvage for reuse of as much of a structure's materials and components as possible. Actually, deconstruction is an informal part of the demolition process to one degree or another. On the other hand, the term demolition emphasizes building removal in its entirety. Though they did not distinguish between recycling and reuse, two reports-one from the Environmental Protection Agency and the other from the National Association of Demolition Contractors-shed light on the scope of C&D waste. The EPA report suggests a conservative recovery rate of between 20 to 30 percent whereas the NADC report suggests material recovery rates of between 80 to 90 percent. In 1998, the year of the EPA report, a total of 288,795 buildings were demolished in the United States (245,000 residential and 43,795 non-residential).
A critical factor in determining a structure's suitability for deconstruction is its design and type. Timber-framed, modular and panelized buildings are the best candidates for deconstruction. For example, a cast-in-place concrete beam is not salvageable whereas a pre-cast concrete beam may be salvageable. In general, there are three hurdles to be overcome once suitability is established. In order of importance these are:
• Greater time requirements
• Higher cost
• Complexity of materials management
One deconstruction company specializing in disassembling large timber-framed buildings in the Pacific Northwest: R.W. Rhine of Tacoma, Wash., has streamlined the process by way of "depanelization." Rather than disassembling on-site where it is time consuming and hazardous, they developed machinery to cut the building into sections that fit onto flatbed trailers. The dismantled sections are then transported to their yard where disassembly occurs at ground level and under controlled conditions. This method allows deconstruction to be as time efficient as is demolition for recycling or disposal, although a large facility and skilled dismantlers are necessary for the operation.
Like people, contracting firms have a "personality"-some are more suited to deconstruction than others. Skill is needed to protect the value of disassembled/salvaged materials/components for sale on the open market. To offset the higher costs of deconstruction, revenue generated from reusable materials recovered and the avoidance of disposal fees are key factors in making the process cost-effective.
Salvaging for reuse creates other problems:
• Where to stack/store
• How to transport
• Matching the salvaged item to a buyer
One solution is known as sale-from-site. All salvaged items are inventoried as to their:
A site-sale for the general public and/or a tour and bid whereby potential buyers make an on-site tour and bid on the salvageable materials still in-place are used as a venue for the sale of salvaged/salvageable materials and components.
SolutionAnother solution and one that is growing in popularity is vertical integration. Here, a construction company or salvage yard owns/operates a demolition/dismantling company or vice-versa. This way, the operation is more efficient and the motivation to disassemble for salvage greater. It's akin to a lumber company owning the forest where the trees they harvest grow.
Federal agencies, such as Housing and Urban Development and Department of Defense, have conducted feasibility studies for deconstruction of thousands of structures under their jurisdiction. This, despite a general consensus that small, light-framed residential housing is not practical for deconstruction due to factors such as labor costs, tipping fees, worker safety requirements and hazardous materials regulations. Non-profit organizations, such as The Green Institute, of Minneapolis, use tax credits whereby the value of salvaged materials can be claimed as tax-deductible charitable donations by the property owner as a motivation for deconstructing rather than demolishing. The Green Institute not only runs two full-time deconstruction crews, it also operates a retail outlet for used building materials-classic vertical integration. In 1999, its revenue was in excess of $560,000.
Even the problem of grading salvaged lumber has gained new ground. Many lumber graders find it difficult to grade salvaged lumber and are reluctant to do so, primarily due to edge and end damage. The Forest Products Laboratory testing of salvaged lumber reveals that the older the lumber the less knots and better grain quality. However, the edge and end damage that is typical of salvaged lumber drops it by one whole grade as a general rule of thumb.
Though there remain many challenges, from an environmental perspective, deconstruction is a good idea and has a bright future ahead. Reuse is one of the four R's (Reduce/ Reuse/Recycle/Restore) of the green building movement. With deconstruction, reuse is stage center with all eyes upon it. Its performance and growth will be observed with keen interest in the years ahead.