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Mark D. Webster, P.E., LEED AP BD+CResearch Team:Simpson Gumpertz & Heger Inc.• Mark D. Webster• Clayton BrownNortheastern University• Prof. Jerome F. Hajjar• Lizhong Wang

Work supported by:National Science FoundationAmer. Inst. of Steel ConstructionHalfenLindapterReinf. Concrete Construction Comm.Capone Iron

Deconstruction is a demolition methodwhere a structure is carefully andmethodically disassembled so as tosalvage as many components as possible.

“Design for Deconstruction” is an approachto new design that anticipates andfacilitates the future deconstruction of thestructure.

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Increase salvage and recycling rates Increase building end-of-life valueReduce consumption of raw materials

(“close the materials loop”) and associatedenvironmental impacts

Reduce energy consumptionReduce waste and landfill demand

Although DfD an excellent strategy forreducing the carbon footprint of buildings(as we will see), it is not a strong climate-change mitigation strategy because thebenefits of DfD occur in the long-termrather than the short-term.

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CircularFlow

Lin

ea

rF

low

USE

discard

landfill/incinerator

manufacture

raw materials

collect sort

consolidate

ship

remanufacture(after Rathman)

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This framing system has repeating bays with similargeometry, beam sizes, and connection types.

This framing system has manyunique pieces that will beimpossible to reuse in adifferent building.

from “Framing a Work of Art,” CivilEngineering, March 1998

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Building systems have different longevities. Keepingsystems separate makes renovations easier, andalso deconstruction.

from How Buildings Learn, byStewart Brand (after Frank Duffy)

from http:// projects.bre.co.uk/

from http:// projects.bre.co.uk/

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from Details for Conventional Wood Frame Construction, by theAmerican Forest & Paper Association

from the Bensonwood web site, www.bensonwood.com

Which connection would you rather take apart?

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The Quicon™ connectionsystem uses standardinterlocking connections.

from the Quicon web site, www.quicon.com

The ConXTechconnection.

from the conxtech web site, www.conxtech.com

This glued plywood floor system will be virtuallyimpossible to take apart. Use screws.

from Design/Construction Guide: Residential & Commercial, by APA – The Engineered Wood Association

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Lindapter ClampedConnections

Larger members are more robust and less subject todamage during use and deconstruction. Fewer piecesto handle will likely reduce deconstruction costs.

from the Bensonwood web site, www.bensonwood.com from Residential Structural Design Guide, by the U.S. Dept. ofHousing and Urban Development

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This vegetable market is constructed of salvaged timber,which will be reusable again at the end of the building’slife.

photo by Mark D. Webster

Composite systems typically increase deconstructiondifficulty and reduce reuse options. Some compositesystems may be reusable as assemblies.

from Stud Welding for Non-ResidentialConstruction, by Nelson Stud Welding

from Murus Structural Insulating Panels Brochure

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Precast concreteplank

Cast-in channels

Steel beam

Clamps

Tongue and groove sidejoint

Bolts

30' 30' 30'

30'

30'

30'

10'

10'

10'

10'

10'

10'

10'

10'

10'

Typical floor plan for DfD system

Staggering plank pattern

Why?• Clamp connectors require

planks being continuous overthe steel beams.

• Enhanced localized stability offloor system

Benefits:• Enables a two-plank strip to

behave like a continuous beamby load transfer between theplanks

• Adds flexibility to the floor plan

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30' 30' 30'

30'

30

'30

'

10'

10'

10'

10'

10'

10'

10'

10'

10'

Typical floor plan for DfD system

End-to-end connections:• Located at the inflection points

to reduce the load transferbetween planks

Longitudinal rebar configuration inplank:• Designed using twice the

moment and shear obtainedfrom continuous beam analysis

• Nine Stories• 30-Foot Bays• Braced Frame Lateral System• Steel Columns and Beams• Conventional Composite

Construction orDeconstructable Planks

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Comparison of conventional composite

construction to DfD slab construction.

Used Simapro LCA software.

Used U.S. Ecoinvent 2.2 and European Life-Cycle

Database for material and transportation LCIs.

Used TRACI 2.1 for environmental impact

assessment.

Modelled material transportation impacts and

construction-phase labor transportation impacts.

Assumed DfD components could be reused three

times on average.

Assumed that material and labortransportation impacts are the sameregardless of whether the DfDcomponents are new or reused.

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0 100 200 300 400 500 600 700 800 900 1000

Conventional Building

DfD Building

kg CO2 eq

Thousands

Conventional Building DfD Building

Production 821000 849000

Mat Transp 23600 32100

Worker Transp 1690 1370

Disposal 55000 56000

Global Warming Potential No Reuse

0 100 200 300 400 500 600 700 800 900 1000

Conventional Building

DfD Building

kg CO2 eq

Thousands

Conventional Building DfD Building

Production 821000 212250

Mat Transp 23600 32100

Worker Transp 1690 1370

Disposal 55000 14000

Global Warming Potential Four Uses

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DfD offers tremendous environmentalbenefits if systems are actually reused.

Assuming the DfD system is reused threetimes, it reduces carbon emissions by 71%relative to conventional compositeconstruction.

If reused only twice, carbon emissions arestill reduced by 63%.

If reused four times, carbon emissions arereduced by 76%.

DfD requires a new mind-set for designers.We’re not accustomed to thinking about theend-of-life (much less the after-life) of ourbuilding designs.

DfD will be most successful for routinebuilding development, such as low- to mid-rise commercial development and housing(which accounts for most construction).These buildings are the most likely to haveregular, repeating floor plans, simpleconstruction, and relatively short life-spans.

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DfD is attracting the attention of buildingdesigners in the North America andEurope. The Building Materials ReuseAssociation in the U.S. is promoting DfD,and excellent DfD guides have beenpublished by the Canadian government,the Scottish government, and CIRIA, aBritish construction research andeducational association.