Student rendering of Kilgore Hall green roof

When Ben Jones chose the roof of Kilgore Hall as the site for a Bio. and Ag. engineering assignment to design a system for mitigating storm water runoff,  little did he know that he would uncover some surprising information at the office of the university architect. The original plans for Kilgore Hall from 1952, hand drafted and decorated with small pencil smears, showed the structural strength for a fourth floor – or the possibility of a green roof.

Ben followed an older gentleman to the document storage area, which looked like a cross between the movie office space and the ancient library at Alexandria. Rolls of blueprints and old binders stretched from the teal carpet floor to the foam board drop ceiling.  The dusty plans for Kilgore Hall showed the load bearing capacity of 90 pounds per square foot. This is enough strength to hold approximately 9 inches of saturated and vegetated mineral soil with a small group of people wandering about. The building was built with the capability to easily add a fourth floor and while the original vision was to provide additional space for experimentation and learning, a new space may come to fruition, albeit in a way never imagined by its originators.

With thoughts of green roofs dancing in his mind, Ben met with a member of campus facilities on the roof to take some photos. Although repairs have been made to the roof, the majority of it dates back to 1987 and the time for a complete replacement rapidly approaches. It became immediately apparent that something serendipitous was rising to the surface. If the roof was to be replaced and a large sum of money was to be spent no matter what, it might be a ripe opportunity to put forward plans for a green roof or the structural potential on the rooftop would be buried under hot rubber for another 20-30 years.

Student graphic showing the possibilities of a green roof on Kilgore Hall’s roof

Ben shared his dream to Horticultural Science design faculty member, Anne Spafford.  They knew that there were as many reasons to be hesitant about a green roof as there were to be excited. Even without the need for structural reinforcement, the upfront costs are intimidating and the long-term benefits are hard for most to visualize.  But they also knew Kilgore Hall was not just any building and its inhabitants are the kind of people who could make this work, and work fantastically. Eventually, Anne suggested they harness student creativity and energy by making this design a special project for her Planting Design class this Fall semester. Ben also happened to be her teaching assistant, and as a relentless green roof nerd, he enthusiastically agreed.  Giving the students a lecture on green roof design and leading them through a site analysis for the roof, the project began.  The views of campus and Hillsborough Street are striking from that unusual vantage point.  Ben describes the experience, “We were all drawn to interact with the treetops around the perimeter. Most people don’t get the chance to stand among the high canopy leaves of old oaks, loblolly pines, cypress, and magnolias. So we all relished those moments. My favorite place was beneath the outstretched “fingertips” of the magnolia on Kilgore Hall’s South East corner. The leaves are morphologically different at the tree’s upper limits; smaller, curled, and thicker to withstand the intensity of unimpeded sunlight. The tree reached just a few feet over the edge of the roof’s parapet wall and glimpses of the phytotron peaked through the foliage.”

The students wandered, measured, photographed, and joked as they recorded what they saw. For all of its great perspective and solitude around the fringe, the roof was still a sweltering black desert of tar, patchy rubber, and the more than occasional lifeless metal protuberance. The only thing even resembling life on the roof itself was the very faint but unrelenting hum of ventilation fans. The objective was to draw their attention to the disheartening waste that the roof represented. Instead of exposing our building to extreme radiation and heat, it is possible to dramatically reduce the temperature and protect the roof membrane from the sun, while at the same time growing beautiful plants and reducing surface water runoff and the associated negative impacts on our watershed. The students recognized this as a very unique opportunity for them to not only learn, but to create something of significance that would have a restorative and enriching effect for all involved.

After the lecture and touring the roof, the 13 students spent two weeks researching, designing, and composing their individual designs with the goal of presenting to members of the department. There are considerable obstacles that need to be navigated before a green roof on Kilgore Hall can become a reality. The hope for the student project’s was not to create anything final but rather to represent a range of potential options through creative exploration and honest communication with the department as a whole. “We want to create something that is an asset to our department,” Ben shared. “Many of the designs focused on how a multipurpose roof garden could support a very wide reaching array of people and causes. When given visual tools people can see the potential to attract new students, provide opportunities for research and interdepartmental collaboration, save money in the long term, support our campus’ vision for sustainability, and create a special place for people to enjoy.” Many people do not know it but the international green roof industry has been growing steadily every year for decades and the need for plant trials and technological innovation in the United States is here. For instance, NC’s Department of Environment and Natural Resources has a substantial framework of engineering requirements for green roofs published in a series of documents but does not have scientifically backed information to aid in the selection of plants, which can make or break a green roof project. Research at NC State could fill that void for our state and even all of the South East.

Everyone’s input is extremely valuable in a process like this, and that was very evident as the students presented their ideas and conversations bubbled to the surface throughout the room. Some departmental faculty members raised concerns regarding access, liability, cost, and maintenance, but were also very supportive and had many great ideas about how this could be a big success. The hypothetical roof garden was energizing people and bringing students and faculty together around a common purpose where everyone had a voice. It may be a while before a plan that everyone can agree upon is reached and a while after that before it becomes a reality. The first steps have been taken, however, to ensure that this department knows what it has. Sometimes motivating oneself to plant the seeds can be the most difficult part of gardening. Then, as you watch them grow you become invested and see what you couldn’t see before. These designs are the seeds and Ben and Anne hope to have a beautiful, productive garden for all growing above the heads of Kilgore Hall.

Any additional inquiries about the roof and or the design project can directed to Ben Jones (bjjones@ncsu.edu) or Anne Spafford (Anne_Spafford@ncsu.edu).

Student graphic showing the possibilities of a green roof on Kilgore Hall’s roof

Student design of a green roof for Kilgore Hall