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The new demolition: a case study compares deconstruction to traditional demolition and examines how both practices approach the recycling of scrap wood.

RE Store, a two-location building material reuse company based in Seattle, has received a grant from the U.S. EPA to develop case studies to document the monetary and environmental benefits of deconstruction versus conventional demolition; provide average volumes, weights and dollar values of different categories of building materials measured over time and during four case studies; and archive and present this data documenting the value of reuse in a manner that is useful to those within the solid waste industry and to the public at large.

A relatively small and simple project covering a footprint of 1,292 square feet was chosen as it represents many of the all-wood, rural structures demolished to make way for urban growth.

The structure was built nearly entirely of wood, using balloon-frame construction. The bulk of the salvageable material was found in the main area (the central 480 square feet) of the two-story barn. The two attached shed roofs to the north and the west were considered valueless from a salvage perspective.

Even in the best parts of the structure, there was some unsalvageable material because of rot or pest damage.

The following report will quantify all material salvaged as well as provide comparisons to estimated salvage potential. Note that a small amount of salvageable material is always lost due to market fluctuations, deconstruction methodology or damage. The salvaged material was quantified according to volume/quantity, weight and market value. The debris remaining after salvage and due to deconstruction was sorted and recycled in the best manner that the industry allows, or placed in a landfill as necessary:

DECONSTRUCTION VS. TRADITIONAL DEMOLITION

Local demolition contractors T n T Recovery and Silver Rain Inc. projected costs, labor and disposal fees under a traditional, machine-based demolition scenario to amount to the following:

* TnT Recovery: Labor-$1,200; Disposal-$2,000 and Total Service-$3,200

* Silver Rain Inc.: Labor-$2,000; Disposal-$3,200 and Total Service-$5,200

* The RE Store: Labor-$3,620; Disposal-$75 and Total Service-$4,470

In either of the above machine-based scenarios, the bulk of the debris would have been recycled locally as "clean wood." The term recycle in this case denotes creating a boiler fuel product.

As can be seen, the RE Store's deconstruction service was 39 percent higher than the lowest bid and 14 percent lower than the highest bid.

The estimated yardage of C&D was as follows:

* TnT Recovery: 140 cubic yards.

* Silver Rain Inc.: 200 cubic yards.

* The RE Store: 70 cubic yards (actual yardage).

T n T Recovery proposed to had the C&D debris to a regional recycling site, estimating 180 cubic yards to be recycled, while the remaining estimated yardage would be placed in a landfill.

Silver Rain Inc. proposed using a local wood recycler, RDS Inc., which would have placed two 100-yard boxes onsite, with an unknown quantity of C&D debris to be recycled and the remaining debris to be landfilled.

The RE Store contracted T n T Recovery to haul 70 cubic yards to local recycling sites, estimating 66.5 cubic yards to be recycled, with the remaining yardage placed in a landfill. The RE Store also hauled 2,200 pounds of concrete to a local recycler.

Labor: T n T Recovery proposed the use of an equipment operator for one day and a laborer for half of a day, as well as an unknown number of drivers for transporting material/recycling. Silver Rain Inc. would have employed an equipment operator for one day. The RE Store employed three deconstruction laborers for a total of 125.5 hours.

Fuel: Both T n T Recovery and Silver Rain Inc. estimated the use of 24 gallons diesel fuel for their excavators and an unknown quantity of fuel for transportation of debris, equipment and laborers. The RE Store used 15 gallons of diesel fuel for its excavator and 13 gallons of gasoline to transport laborers and materials approximately 132 miles.

THE TAKE-DOWN

The first stage in the deconstruction process involved salvaging all reusable and high-value items from the interior and exterior of the property. This included: removing all antique electrical switches, removing several craftsman-style windows, pulling and de-nailing all trim, salvaging the old-growth fir stair treads, and removing the barn doors from their wall openings.

Since a large portion of the structure--the attached shed roofs on the west and north of the main barn structure--were considered to have little to no salvage potential and a track hoe was incorporated into deconstruction at later stages, the shed roofs were collapsed. The remains of the north roof were placed in a pile atop the remains of the west roof. To collapse the attached shed roofs, deconstruction workers cut the roofs at their upper most connections and pulled them from the main structure, utilizing cables and a four-wheel drive pickup. At the end of the entire deconstruction process, a track hoe was used to break up the large pile of debris and compact it into the onsite recycling bins.

Once the interior was stripped and the attached roofs were down, the deconstruction crew then began removal of the main roof structure. The cedar roofing and shiplap was cut into 4-foot wide strips, knocked and pried from the rafters from inside the structure and sent to the debris pile. The rafters themselves were then cut from the walls and the ridge, inspected for quality and either sent down to be de-nailed or placed in the debris pile.

Note that every effort is made to keep like lengths of materials together throughout the deconstruction process to maintain de-nailing, loading and measuring efficiency. When de-nailing, it is best to de-nail the longest lengths first and then load them directly onto the waiting truck or trailer, ensuring the most neat and stable load.

The deconstruction team then began removal of the upper flooring by prying it from the joists with long bars. This exposed the upper floor/ceiling joists, which were then cut from the walls, inspected for quality, and either sent to the de-nailing station or placed in the debris pile.

The RE Store crew then collapsed the exterior walls. This was done by cutting the top plate of each wall from its connection to the adjoining exterior wall and inwardly collapsing the cut section of wall, employing supports fashioned from salvaged lumber, ropes and cables to prevent remaining walls from falling unexpectedly and harming members of the deconstruction team. All exterior walls were collapsed in the same fashion. Once the four walls were on the ground, the siding was pried loose and the walls were knocked/pried apart with bars and heavy hammers, each stud board assessed for value and then sorted for de-nailing and load-out or placed in the debris pile.

When the bottommost section of flooring was exposed, the remaining tongue and groove flooring was pried from the sub floor, inspected for quality and sorted accordingly. The remaining sub-floor was left for the track hoe, as it had no salvage value.

The rest of this "hybrid" approach to demolition/deconstruction is similar to conventional, machine-based demolition practices. One person operates the machine, while the remaining laborers work on the ground to rake what small debris the machine cannot pick up. After the sub floor and poured concrete foundation were removed, the deconstruction crew was ready for final sight cleanup--the exposed earth within and around the buildings footprint was raked clean.

* Note that the deconstruction crew also carries out daily cleanup operations to prevent debris from being blown onto neighboring properties.

* Note that approximately 4 yards of poured concrete was hauled by members of The RE Store field staff to a local concrete recycler.

It should also be noted that several extra steps were taken during the load out/measuring process in order to satisfy the terms of the case study. Each item or group of items needed to be carefully weighed and measured as it was unloaded and priced at the RE Store's retail outlet, requiring additional labor from members of the field crew. Special forms, used to document the weight of the material, were used in addition to those normally used to document material's volume and value, requiring more time for paperwork.

THE END RESULT

The actual salvage value of materials differs from estimated salvage potential due to the loss of material from damage incurred by deconstruction methodology, impossibility of salvage due to the manner in which the building was constructed and loss of estimated value due to poor salability. By incorporating deconstruction practices into the demolition of this structure, The RE Store saved from the landfill 5,413 pounds of reusable material, valued at $2,647. Under the scenario presented by T n T Recovery, 0 percent would have been saved for re-use, up to 95 percent recycled and the remaining debris placed in a landfill.

The total real volume of the building should be seen as the combined volumes of the salvaged materials and the debris. The total real volume of the structure was estimated at around 110 cubic yards. This real value can be compared with the bid estimates, and industry standard weight to volume conversion ratios. This estimate shows that 36.4 percent of the original volume was saved directly for re-use, 60.5 percent recycled, and 3.1 percent placed in a landfill.

At the project's end, it was shown that 68 percent of the 2 x 6 lumber, 65 percent of the siding and 71 percent of the "utility sheathing" was saved directly for re-use. Unfortunately only 4 percent of the shiplap sheathing was saved for local use, as this type of material is often difficult to market.

Summary of Results

* Square footage of structure's footprint: +/- 1,292 square feet

* Total volume of structure: 110 cubic yards

* Total weight of structure: 15,921 pounds

* Combined weight of salvaged materials: 5,523 pounds

* Percentage salvaged: 34.6 percent

* Combined weight of recycled materials: 9,711.6 pounds

* Percentage recycled: 64 percent

* Weight landfilled: +/-1,483.26 pounds

* Percentage landfilled: 3.1%

* Estimated value of recycled material: $2,647.47

* Value per square foot: $2.05

* Weight per square foot: 12.32 pounds

* Value of salvaged materials: $.48 per pound.

The main expense incurred during deconstruction was labor. Four skilled deconstruction laborers were paid approximately $2,208.80 for 125.5 hours of labor, not including benefits or accounting for L&I expenses and taxes. The RE Store consumed roughly 16 gallons of gasoline over a combined total of 132 miles. Fuel consumption proved to be higher for deconstruction than for the proposed fuel use in a conventional scenario, due to transportation of material and laborers. The only significant tool cost was for the rental of the track hoe, which amounted to approximately $580.

It should be noted that using a hybrid method of deconstruction, incorporating a track hoe to handle marginal materials and debris, helps maintain economic viability and minimizes labor costs.

The RE Store, due to its status as a 501 (c) 3 non-profit, offered the client the added benefit of a tax deduction for the total value of their donation of salvaged building materials. In the case of this project, this donation carried an estimated value of $2,647.

THE MAKE-UP

A detailed description of the material that made up the demolished structure is available in a Web sidebar at www.CDRecycler.com.

The author is a project manager with The RE Store, Seattle, and can be contacted at Erin@re-store.org.
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Title Annotation:WOOD RECYCLING FOCUS
Author:Marden, Erin
Publication:Construction & Demolition Recycling
Date:Sep 1, 2006
Words:1917
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