The U.S. Environmental Protection Agency, Habitat for Humanity, the Building Materials Reuse Association and numerous other organizations are promoting the deconstruction of old buildings instead of demolishing them. At the same time, these groups are also urging that new buildings be designed and constructed so that they can easily be taken apart at the end of their useful life.

In the case of houses, the most important details to consider when planning for future dismantling are the fasteners and adhesives, that is, nails, screws and glues.

One of the biggest reasons that salvaged lumber from old houses is deemed unusable is the cracks and splintering caused by trying to extract deeply embedded nails. Had the same pieces been attached with decent quality screws, these would be easy to remove and the salvaged pieces could have a second life in another house. Screws can be removed faster than nails, and this would also speed up the deconstructing and reduce its cost, said Dave Bennink, a deconstructor based in Bellingham, Wash., But, he cautioned, poor quality screws can be stripped on their first use and these are harder to extract than nails.

Home builders resist using screws because they cost more than nails, and they require more time to install, Bennink said. But, he pointed out, a screw can give a tighter, stronger connection so you need fewer of them. When this is taken into account, the cost and labor differences between screws and nails tend to disappear. Another negative in salvaging houses built after 1980 is adhesives and the nearly universal practice of both gluing and nailing floor framing members together. “Where you glue two things together, you ruin both trying to cut or pry them apart,” Bennink said. “If I have 50 4 by 8-foot sheets of OSB that are screwed I can save every one. If I have 50 4 by 8-foot sheets of OSB that are nailed and glued, I’m lucky to save any of them.”

Another problem with disassembling newer houses is the electric wiring said Brad Guy, a deconstructor based in Pittsburgh and the co-author of “Unbuilding,” (Taunton, 2007, $20). Most electricians run their wiring through holes they drill into the wall studs, but this practice makes a stud worthless from a reuse perspective. Guy’s preferred solution is to run the wiring in an easily accessible raceway at the ceiling line or the wall base. This modification would make the electrician’s job easier, and homeowners could easily modify the wiring in the future, if they want to add the latest in “smart-house” technology.

To test these ideas, Guy worked with fellow architecture school graduate Andrea Korber, who designed a “Disassembly House” in Atlanta. The house was built by Robert Soens’s Decatur, Ga., firm, Pinnacle Custom Builders. Not only will the house be easy to dismantle in 40 or 50 years, it will be easy for the owners to move interior walls to accommodate their changing needs as they live in it.

Structural insulated panels, known as SIPS were used for the exterior walls and roof. These combine the framing and insulation into a single framing piece so that the exterior walls will be easy to remove. Inside there are no bearing walls. Instead Korber designed a wall system of made up of 4-foot panels that are light enough for the homeowners to easily reposition them.

Though the innovative interior wall panel system required quite a bit of finagling initially, Soens said his crew quickly learned how to install them, and the new system increased his cost by less than five percent. All the connections were fastened with screws and so far this has worked well, he said.

December 2008