Designing for Deconstruction/Disassembly (DfD) is a method of reducing construction and demolition wastes from buildings and other structures. It is different from demolition, which is mostly concerned with clearing the site of an existing structure quickly. Deconstruction is more like "harvesting" or reclaiming useful materials from a decommissioned structure. It is sometimes referred to as "Construction in Reverse."

Historical Background


Reclamation and reuse of building materials has been a common practice for centuries. It has gained a new appreciation in light of recent efforts to improve sustainability practices in construction. Particularly in Europe, reusing old limestone bricks and other architectural components has been a popular way to link new construction to the "old heart" of a town or region. As buildings have become more complex over time, however, developing new methods of deconstruction has overshadowed discovering new uses for reclaimed materials.

Types of Deconstruction

Non-Structural

Non-structural deconstruction involves removing furnishings and finishings of a building. This includes appliances, doors, windows, and edging or framing.

Structural

Structural deconstruction is the disassembly of major supporting and load-bearing components of a building. Traditionally, such intensive deconstruction was only employed for valuable and expensive components, such as old-growth wood. More recently, however, items such as common lumber have become a popular reclaimable material.

Current Practices


Today, 55% of deconstruction labor hours are taken by processing. This includes transportation, organization, and storage of materials. Only 37% of labor hours are taken by the actual disassembly of the building[1] . To address this, DfD has grown to incorporate much more than simply "taking a building apart."

Process

There are three key stages to the deconstruction process:
  • Designing for Deconstruction/Disassembly (DfD)
  • Soft-Stripping (Non-structural)
  • Roof-to-Foundation (Structural)

DfD

Simple, Consistent Construction

Buildings designed for ease of disassembly must also be designed for simple construction. Standardized mechanical connections are one way to make both easier. Common connection types are rigid key-type joints, Saxe clips, and cast steel nodal clips. Non-complex built components are
another way to keep construction simple. At this design stage, involving construction professionals is highly-recommended. Contractors, fabricators, and construction managers are more knowledgeable than architects about which component types are simplest to construct.

Figure 1 - Example of rigid key joint
Figure 1 - Example of rigid key joint

Durable, Reusable Materials
Implementing reusable materials in the design of a new building is imperative. If a material becomes unusable after one building life-cycle, it is not safe for repurposing. Some materials, if not reusable, can be economically recycled. For example, it takes 75% less energy to recycle steel than to produce virgin steel. Steel also happens to be an infinitely recyclable material[2] .

Visible Construction Layers

Designing building layers to be easily accessible and visible helps deconstruction crews determine the order of component disassembly. One method is to reduce the number of extraneous finishes, which additionally saves on material costs. Examples include stained concrete flooring, painted CMU blocks, and architecturally exposed structural steel.

Modular & Separable Components

Pre-fabrication of modular structural units not only make deconstruction easier, they make subsequent stacking and transportation easier, as well. Separable components are unique because they are mechanically fastened or bolted to one another. It is important to avoid nails, screws, welds, and most adhesives which could damage materials or make their extraction more difficult. Non-structural fixtures should ideally be pre-wired with mated plugs and clip-on components to expedite both installation and removal.

Consolidated Utilities

Reclaiming winding pipes, wires, and ducts is a painstaking process, and is often avoided to save time. DfD often places utilities in central locations in the building. Some buildings even incorporate non-structural removable walls with utilities embedded within them.

Renovation-Ready Building

Open-bay designs and non-structural walls are the most common recommendations for enabling easy renovation of building space. The most effective of these buildings would be considered capable of "Over-the-Weekend" repurposing. Another unique structure that could be designed into buildings is a lift shaft. These are structural openings that allow small driving lifts to access several floors from one parked location. They are useful during both construction and deconstruction. However, while the building is in use, they are often concealed or blocked off.

Figure 2 - Open-Bay Building Design
Figure 2 - Open-Bay Building Design


Building Designs with Included Deconstruction Instructions

Drafting designs with both construction and deconstruction instructions simply takes the guess-work out of building disassembly. Time, energy, and resources can all be saved when exact specifications and directions are given to the deconstruction crew.

Incorporated Safety Measures

As with any construction or deconstruction project, worker safety is paramount. DfD buildings can oftentimes eliminate the need for scaffolding reinforcement, fall protection, and overhead work by incorporating special anchors in or on lightweight structural components. Building with environmentally safer materials also eliminates the need for respiratory equipment during deconstruction.

Benefits

Waste Reduction

The main benefit from DfD and deconstruction in general is the reduction in waste compared to demolished buildings. In the US, 92% of landfill-destined Construction and Demolition (C&D) waste is from demolitions. Furthermore, C&D waste comprises 1/3 of the total landfill-destined waste[3] per year.

Material and Transportation Cost Reduction

Additional benefits include the reduction in virgin material required for new construction, and savings on transportation costs for materials used in on-site or nearby reconstruction.

Drawbacks

Time

Compared to typical one-day demolition, deconstruction can take up to several weeks. DfD attempts to minimize this time difference with the practices mentioned above, but deconstruction and reclamation will always take longer than demolition and disposal.

Labor cost

For first-time deconstruction on a building, it is estimated that the labor cost will not be outweighed by the resale/repurposing of recovered material. At best, first-time deconstruction costs can be met evenly. Some forms of remuneration from deconstruction are as follows:
  • Tax write-offs
  • Replacing more-expensive new materials
  • Salvaging and selling valuable components
  • Savings on landfill fees

If deconstructions are well-planned, they can become more economical. This requires having an immediate plan for the reuse or resale of the materials. If no design plans for immediate reuse exist, contacting local reclamation companies, antique collectors, salvage/scrap yards, or even the local Habitat for Humanity is a good way to start.

Theft

Some building materials, if especially rare or valuable, are likely to be stolen if the deconstruction site is not properly secured. Many deconstruction crews forget this.Theft is still a prevalent problem, even on demolition sites.

Hazardous Materials

Hazardous materials not only pose a danger to workers, they also have expensive and highly-regulated disposal processes.

Deconstructing Complex Systems

Some of the most dangerous and complicated systems to disassemble are cantilevers and pre/post-stressed members. This is particularly problematic, because these are also some of the most common pre-fabricated elements. In general, pre-fabricated members should make construction and deconstruction easier, but not all are created equal. This is an example of some of the trade-off evaluations involved in DfD.

Success Stories


EPR

European legislation has successfully implemented a plan that increases the disposal and recycling responsibilities for companies in several countries. It is called Extended Producer Responsibility (EPR). It holds manufacturers and other companies accountable for the entire lifespan of their products, in hopes to keep these items out of landfills. Companies will often provide recycling services for their product. Today, about 32 states in the US have effectively passed and maintain EPR laws. There is currently no federal EPR legislation, however.
Figure 3 - Depiction of EPR Process
Figure 3 - Depiction of EPR Process

Challenges & Improvement Goals


Design

Many buildings that will be deconstructed today have not been designed for disassembly. Designers have typically assumed that their buildings will simply "last forever." Applying DfD principles to new buildings will improve working conditions and processes for deconstruction crews in the future.

Policy

At this time, certification standards for re-purposed materials are lacking. With no applicable codes to reference, designers are in a tricky spot designing buildings with reclaimed structural components. In addition to this, the benefits of DfD are not well-defined nor properly advertised. The demolition industry is mostly uninformed, and markets with demand for recycled materials can often be difficult to locate.

Future Development


Legislation

Oftentimes, methods simply follow the money, will and only jump through hoops when required. DfD is still a new concept, and not always economically incentivizing. Many believe that applying new laws will help push businesses into more environmentally responsible construction practices like DfD. The illegalization of discarding certain materials may be a reasonable approach, as well as raising the costs of landfill disposal.

Research

As with many new practices, unanswered questions require development and exploration. DfD would benefit from additional research to discover new design methods, deconstruction methods, and tools. The following companies and institutions are currently seeking to answer these questions:


References



  1. ^ Pulaski, Michael, Hewitt, Christopher, Horman, Michael, Guy Bradley. (ND) “Design for Deconstruction: Material Reuse and Constructability.” Department of Architectural Engineering Pennsylvania State University. <http://www.usgbc.org/Docs/Archive/MediaArchive/204_Pulaski_PA466.pdf> (12/2/2015)
  2. ^ Designing Buildings, Ltd. (2015) “Design for Deconstruction” Designing Buildings Wiki. <http://www.designingbuildings.co.uk/wiki/Design_for_deconstruction> (12/1/2015)
  3. ^ Kibert, Charles J., Chini, Abdol R., Languell, Jennifer. (2001) “Deconstruction as an Essential Component of Sustainable Construction” CIB World Building Congress. <https://www.irbnet.de/daten/iconda/CIB3122.pdf> (12/1/2015)



Historical Background | Current Practices | Success Stories | Challenges & Improvement Goals | Future Development | References