Roof Retrofit: Medical Center Recycles Roofing Materials

As organizations grow increasingly conscious of the impact facilities have on the environment, managers are under greater pressure to minimize this impact. To that end, Duke University Medical Center aims to prevent as much roofing material as possible from taking up space in landfills.

For this reroofing project, the medical center was able to recycle 100 percent of the old roof — about 730 tons of material — to prevent it from entering a landfill, Pennigar says.

Where did the old material go? Workers reused the roof insulation to help create landscape berms on the campus, he says. And workers used the stone ballast vacuumed off the roof by a commercial vacuum service to stabilize roads around the medical center.

This project is not the first time the medical center had attempted such an effort, Pennigar says. A 2006 reroofing project served as a precursor to this project's focus on sustainability.

"That was our first really good experience with recycling materials," he says.

Focus on the Future

For Pennigar, the most recent reroofing project offers several lessons for future projects.

First, the project is a case study on the impact pressurization problems can have on the performance of the roof and the conditions in the facility. Pressurization problems related to the original roof's design created hazards related to smoke, noise and odors migrating into the building through the plenum and air intakes.

Second, it served as a reminder to consider the long-term implications of roofing decisions or, as Pennigar puts it, "Begin with the end in mind." By that, he means design the roof both to offer maximum, long-term protection to the facility and its occupants, and to prevent performance problems that will put future managers in a difficult situation.

Says Pennigar, "You have to think about the poor chap who has to decide whether to repair or replace it in 20 or 30 years."

Project at a Glance Duke University Medical Center in Durham, N.C. The patient tower was built in 1979. Its 12,000-square-foot roof contains 1,100 linear feet of wall flashing. The old roof included three different levels, a penthouse with two large intake fans, and a 70-foot-long, concrete-block return-air plenum, which creates high-velocity, negative-pressurization conditions. The old roof was an inverted roof-membrane assembly (IRMA), which consisted of a built-up membrane installed over a structural concrete slab and topped by insulation. The reroofing project started in late 2009 and took about 16 weeks to complete. The new roof is a fully adhered, thermoplastic polyolefin (TPO), single-ply system. The medical center recycled 100 percent of the old roof — about 730 tons of material — to prevent it from entering a landfill. — Dan Hounsell

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